Drought resistance and resilience of rhizosphere communities in forest soils from the cellular to ecosystem scale - insights from 13C pulse labeling

The link between above- and belowground communities is a key uncertainty in drought and rewetting effects on forest carbon (C) cycle. In young beech model ecosystems and mature naturally dry pine forest exposed to 15-yr-long irrigation, we performed 13C pulse labeling experiments, one during drought and one 2 wk after rewetting, tracing tree assimilates into rhizosphere communities. The 13C pulses applied in tree crowns reached soil microbial communities of the young and mature forests one and 4 d later, respectively. Drought decreased the transfer of labeled assimilates relative to the irrigation treatment. The 13C label in phospholipid fatty acids (PLFAs) indicated greater drought reduction of assimilate incorporation by fungi (-85%) than by gram-positive (-43%) and gram-negative bacteria (-58%). 13C label incorporation was more strongly reduced for PLFAs (cell membrane) than for microbial cytoplasm extracted by chloroform. This suggests that fresh rhizodeposits are predominantly used for osmoregulation or storage under drought, at the expense of new cell formation. Two weeks after rewetting, 13C enrichment in PLFAs was greater in previously dry than in continuously moist soils. Drought and rewetting effects were greater in beech systems than in pine forest. Belowground C allocation and rhizosphere communities are highly resilient to drought.

First Report of Alternaria alternata Causing Leaf Spot on Catalpa bungei in China

Catalpa bungei originates from China. It is fast-growing and possesses a vertically aligned trunk, rendering it a commendable construction material and a significant economic species. In July 2022, a serious leaf spot occurred in the LanLake farm (surveyed area of about 700 acres) in Nanyang (33°3'23" N, 112°28'50" E), Henan Province, China. The incidence rate of leaf disease reached 54% (n=100). The disease initially manifested as irregular round spots with a yellowish-brown hue, subsequently extending in all directions. Later, the lesion periphery exhibited a darkening effect, leading to yellowing. Twenty diseased leaves were randomly collected and cut into small pieces at the interfaces between infected and healthy tissues. The tissues were sterilized in a solution of 75% ethanol and 1% NaClO for 30 seconds and 1 minute, respectively. After rinsing in sterile water, the pieces were placed on potato dextrose agar (PDA) plates and incubated at 25°C for 5 days. A total of 29 purified fungal strains were acquired, exhibiting comparable phenotypes in terms of morphological characteristics. Three strains (QS1-1, QS1-2, and QS1-3) were isolated for subsequent investigations. The colony exhibited abundant aerial mycelium with shades ranging from dark green to grey-brown on the reverse side. To analyze the morphological characteristics of conidia, potato carrot agar (PCA) was used as the culture medium and incubated at 25°C with a 12-hour light/dark cycle. Conidia were obclavate or spheroidal, dark brown, with 3 to 5 transverse septa, and 1 to 4 longitudinal septa, measuring 12.4 to 36.7 × 4.4 to 9.0 μm (n=100), with conical beak lengths ranging from 0 to 4.3 μm. These morphological traits suggested that the pathogen shares similarities with the Alternaria species. The rDNA internal transcribed spacer (ITS), translation elongation factor 1-alpha gene (tef1), glyceraldehyde 3-phosphate dehydrogenase gene (gapdh), and RNA polymerase II second largest subunit (rpb2) were amplified for further molecular identification. The resultant sequences were submitted to GenBank with the following accession numbers: OR733559, OR742124, OR761873 (ITS), OR939796, OR939797, OR939798 (tef1), OR939801, OR939802, OR939803 (gapdh), and PP054846, PP054847, PP054848 (rpb2). A Phylogenetic tree was constructed of combined genes (ITS, tef1, gapdh, and rpb2) of sequences, alongside the sequences of the type strains by the neighbor-joining method. The three strains formed a clade with the strains CBS 121456 of Alternaria alternata in phylogenetic trees, being separated from other Alternaria spp. The morphological features and molecular analyses supported the strains as members of Alternaria alternata (Woudenberg et al. 2015). To validate pathogenicity, a conidial suspension (106 conidia ml-1) of all three strains was inoculated onto three healthy leaves of five seedlings, with 50 μl of inoculum absorbed with cotton balls. Another group of five plants received sterile water as a control. All plants were incubated in a climate chamber at 28°C and 90% relative humidity. Four days post-inoculation, lesions resembling natural phenomena were observed, whereas control plants showed no symptoms. Subsequent reisolation produced cultures that were morphologically and molecularly identical to the original strains, fulfilling Koch's postulates. Stem canker of C. bungei caused by Phytophthora nicotianae has been reported in China (Chang et al. 2022). This is the first report of A. alternata causing leaf spots on C. bungei in China. Further research is required on management options to control this disease and the host range still needs to be clarified for accurate disease management.

First Report of powdery mildew of Quercus guyavifolia (Fagaceae) Caused by Erysiphe quercicola

Oaks are the most abundant trees in naturally regenerated forests in China, play a crucial role in preventing soil erosion and maintaining ecological stability (Du et al. 2022). Quercus guyavifolia H. Léveillé (Fagaceae family, Subgenus Cerris, section Ilex), is endemic in China, distributed in the southeastern boundary of the Qinghai-Tibet Plateau, with elevations from 2, 000 - 4, 500 m a.s.l. (Denk et al. 2018; Sun et al. 2016). Powdery mildew is a prevalent disease of oaks with up to 60% of foliage infection, which can induce leaf necrosis or deformation and might contribute to oak decline (Marçais and Desprez-Loustau 2014). In September 2023, we found leaves of Q. guyavifolia near Yunnan Baima Snow Mountain covered with white fungal colonies. Diseased Q. guyavifolia plants were transplanted into a greenhouse at Yunnan University for pathogenicity tests. Conidia from diseased plants were blown into twenty healthy Q. guyavifolia seedlings by cold air blower and five non-inoculated healthy seedlings were used as control. The inoculated seedlings developed powdery mildew symptoms within ten days on both sides of the leaves. Trypan blue staining was used to identify the pathogen that infects Q. guyavifolia (Xiao et al. 2017). Microscopic examination revealed abundant conidia and extensive branched hyphae on leaves, similar to the characteristics of powdery mildew fungi. The mean length and width of conidia were 29.06 ± 3.96 × 9.52 ± 1.36 μm (n = 50). We collected fungi (YNBAIMAXS01) and extracted genomic DNA from five diseased plants (from the same location) using the CTAB method. We amplified and sequenced the ITS (Gardes and Bruns, 1993), MS294, and MS447 (two nuclear protein-encoding genes; Feau et al. 2011; GenBank numbers: PP079015, PP083693, PP083694). BLAST analysis revealed 100% identity of above three sequences with the ITS of Erysiphe quercicola isolate DACA010 (GenBank accession MT569439), MS294 of E. quercicola isolate GEM09_11_FRTB1 (GenBank accession KY348509), and MS447 of E. quercicola isolate A1I1.5 (GenBank accession KY466619). Therefore, the isolate YNBAIMAXS01 was identified as E. quercicola based on its morphological and molecular characteristics. Sequences from the above three regions for YNBAIMAXS01 and five Erysiphe species were used to construct a Maximum likelihood (ML) tree. In addition, we constructed a ML tree using only the ITS region of YNBAIMAXS01 and eight Erysiphe species from GenBank to better distinguish E. quercicola from these species. Both trees were constructed using MEGA X with K2 + G as best model. The ML trees confirmed the powdery mildew fungi isolated from Q. guyavifolia is closely related to E. alphitoides. To date, thirty-four powdery mildew species belonging to genus Erysiphe have been found affecting Quercus and nine oak species can be infected by E. quercicola (https://fungi.ars.usda.gov/). To our knowledge, this is the first report of powdery mildew caused by E. quercicola on Q. guyavifolia, thus the development of control strategies and disease management is urgently needed.

Where the small things are: Modelling edge effects on mouse lemur population density and distribution in northwestern Madagascar

Edge effects result from the penetration to varying depths and intensities, of abiotic and biotic conditions from the surrounding non-forest matrix into the forest interior. Although 70% of the world's forests are within 1 km of a forest edge, making edge effects a dominant feature of most forest habitats, there are few empirical data on inter-site differences in edge responses in primates. We used spatially explicit capture-recapture (SECR) models to determine spatial patterns of density for two species of mouse lemurs (Microcebus murinus and Microcebus ravelobensis) in two forest landscapes in northwestern Madagascar. The goal of our study was to determine if mouse lemurs displayed spatially variable responses to edge effects. We trapped animals using Sherman live traps in the Mariarano Classified Forest (MCF) and in the Ambanjabe Forest Fragment Site (AFFS) site within Ankarafantsika National Park. We trapped 126 M. murinus and 79 M. ravelobensis at MCF and 78 M. murinus and 308 M. ravelobensis at AFFS. For M. murinus, our top model predicted a positive edge response, where density increased towards edge habitats. In M. ravelobensis, our top model predicted a negative edge response, where density was lower near the forest edges and increased towards the forest interior. At regional and landscape-specific scales, SECR models estimated different density patterns between M. murinus and M. ravelobensis as a result of variation in edge distance. The spatial variability of our results using SECR models indicate the importance of studying the population ecology of primates at varying scales that are appropriate to the processes of interest. Our results lend further support to the theory that some lemurs exhibit a form of ecological flexibility in their responses to forest loss, forest fragmentation, and associated edge effects.

Concurrent Clade I and Clade II Monkeypox Virus Circulation, Cameroon, 1979-2022

During 1979-2022, Cameroon recorded 32 laboratory-confirmed mpox cases among 137 suspected mpox cases identified by the national surveillance network. The highest positivity rate occurred in 2022, indicating potential mpox re-emergence in Cameroon. Both clade I (n = 12) and clade II (n = 18) monkeypox virus (MPXV) were reported, a unique feature of mpox in Cameroon. The overall case-fatality ratio of 2.2% was associated with clade II. We found mpox occurred only in the forested southern part of the country, and MPXV phylogeographic structure revealed a clear geographic separation among concurrent circulating clades. Clade I originated from eastern regions close to neighboring mpox-endemic countries in Central Africa; clade II was prevalent in western regions close to West Africa. Our findings suggest that MPXV re-emerged after a 30-year lapse and might arise from different viral reservoirs unique to ecosystems in eastern and western rainforests of Cameroon.

Plant-soil interactions alter nitrogen and phosphorus dynamics in an advancing subarctic treeline

Treelines advance due to climate warming. The impacts of this vegetation shift on plant-soil nutrient cycling are still uncertain, yet highly relevant as nutrient availability stimulates tree growth. Here, we investigated nitrogen (N) and phosphorus (P) in plant and soil pools along two tundra-forest transects on Kola Peninsula, Russia, with a documented elevation shift of birch-dominated treeline by 70 m during the last 50 years. Results show that although total N and P stocks in the soil-plant system did not change with elevation, their distribution was significantly altered. With the transition from high-elevation tundra to low-elevation forest, P stocks in stones decreased, possibly reflecting enhanced weathering. In contrast, N and P stocks in plant biomass approximately tripled and available P and N in the soil increased fivefold toward the forest. This was paralleled by decreasing carbon (C)-to-nutrient ratios in foliage and litter, smaller C:N:P ratios in microbial biomass, and lower enzymatic activities related to N and P acquisition in forest soils. An incubation experiment further demonstrated manifold higher N and P net mineralization rates in litter and soil in forest compared to tundra, likely due to smaller C:N:P ratios in decomposing organic matter. Overall, our results show that forest expansion increases the mobilization of available nutrients through enhanced weathering and positive plant-soil feedback, with nutrient-rich forest litter releasing greater amounts of N and P upon decomposition. While the low N and P availability in tundra may retard treeline advances, its improvement toward the forest likely promotes tree growth and forest development.

Clean and sustainable environment problems in forested areas related to recreational activities: case of Lithuania and Turkey

Introduction

With the acceleration of social life, people's interest and demand for forestry recreation activities is increasing. However, with this increase, it is inevitable that negative environmental effects will occur. Particularly mass participation poses an important risk for environmental sustainability. In this context, the aim of this study is to determine the recreational activities organized in forest areas in Turkey and Lithuania, the environmental effects of these activities and the precautions to be taken.

Methods

In Turkey and Lithuania, interviews were conducted to determine the attitudes of experts involved in recreational activity processes towards a clean environment and environmental sustainability. A semi-structured interview form was used in the interviews with forest operators and other experts. The sample group of the research consists of 17 experts from Turkey and Lithuania.

Results

According to the results of the research, recreational activities are organized in forest areas in both countries, but the most important problem related to these activities is waste production. In addition, there is also damage to the natural environment. Although there are legal regulations in both countries, there are no definite results in solving environmental problems.

Conclusions

It can be said that necessary measures such as raising awareness of people and ecological education should be taken in order to ensure the right of individuals to live in a safe and clean environment and at the same time to ensure sustainability in forest areas. as the improvement of legal regulation.

Forestry Applications of Space-Borne LiDAR Sensors: A Worldwide Bibliometric Analysis

The 21st century has seen the launch of new space-borne sensors based on LiDAR (light detection and ranging) technology developed in the second half of the 20th century. Nowadays, these sensors offer novel opportunities for mapping terrain and canopy heights and estimating aboveground biomass (AGB) across local to regional scales. This study aims to analyze the scientific impact of these sensors on large-scale forest mapping to retrieve 3D canopy information, monitor forest degradation, estimate AGB, and model key ecosystem variables such as primary productivity and biodiversity. A worldwide bibliometric analysis of this topic was carried out based on up to 412 publications indexed in the Scopus database during the period 2004-2022. The results showed that the number of published documents increased exponentially in the last five years, coinciding with the commissioning of two new LiDAR space missions: Ice, Cloud, and Land Elevation Satellite (ICESat-2) and Global Ecosystem Dynamics Investigation (GEDI). These missions have been providing data since 2018 and 2019, respectively. The journal that demonstrated the highest productivity in this field was "Remote Sensing" and among the leading contributors, the top five countries in terms of publications were the USA, China, the UK, France, and Germany. The upward trajectory in the number of publications categorizes this subject as a highly trending research topic, particularly in the context of improving forest resource management and participating in global climate treaty frameworks that require monitoring and reporting on forest carbon stocks. In this context, the integration of space-borne data, including imagery, SAR, and LiDAR, is anticipated to steer the trajectory of this research in the upcoming years.

Fractionation and Characterization of Metallic Elements in Soils in Land Use Systems

Land use has a great impact on soil dynamics. The soils of various land use systems in Central Karakoram have been under immense pressure in the recent past due to certain anthropogenic activities such as land use practices and land use cover changes. These influences have an impact on the spatial distribution of metallic elements (MEs) in the soils of various land uses. Herein, we investigated the occurrence of the MEs, copper (Cu), zinc (Zn), and nickel (Ni), in soils of various land uses such as the permafrost, pasture, forest, and agricultural lands of the Central Karakorum region. The MEs were extracted in exchangeable, adsorbed, organically bound, carbonated, precipitated, and residual forms. The concentrations of MEs showed a significant dependence on the extraction method used, and the extraction trend followed the order of EDTA > HNO3 > KNO3 > NaOH > H2O. Zn showed the highest concentration compared to Ni and Cu in all extractions, whereas the land uses' ME concentration followed the order of agricultural land > permafrost > forest > pasturelands. The highest values of total Zn, Ni, and Cu were 712 ± 01 mg/kg, 656 ± 02 mg/kg, and 163 ± 02 mg/kg, respectively, in agricultural soil. The ME concentration showed significant variations between different land uses, and the highest concentration was noted in agricultural soil. Zn was found to be a dominant ME compared to Ni and Cu. We believe this effort will provide opportunities for scholars to investigate MEs around the globe.

A Comparative Analysis of UAV Photogrammetric Software Performance for Forest 3D Modeling: A Case Study Using AgiSoft Photoscan, PIX4DMapper, and DJI Terra

Three-dimensional (3D) modeling of trees has many applications in various areas, such as forest and urban planning, forest health monitoring, and carbon sequestration, to name a few. Unmanned Aerial Vehicle (UAV) photogrammetry has recently emerged as a low cost, rapid, and accurate method for 3D modeling of urban and forest trees replacing the costly traditional methods such as plot measurements and surveying. There are numerous commercial and open-source software programs available, each processing UAV data differently to generate forest 3D modeling and photogrammetric products, including point clouds, Digital Surface Models (DSMs), Canopy Height Models (CHMs), and orthophotos in forest areas. The objective of this study is to compare the three widely-used commercial software packages, namely, AgiSoft Photoscan (Metashape) V 1.7.3, PIX4DMapper (Pix4D) V 4.4.12, and DJI Terra V 3.7.6 for processing UAV data over forest areas from three perspectives: point cloud density and reconstruction quality, computational time, DSM assessment for height accuracy (z) and ability of tree detection on DSM. Three datasets, captured by UAVs on the same day at three different flight altitudes, were used in this study. The first, second, and third datasets were collected at altitudes of 60 m, 100 m, and 120 m, respectively over a forested area in Tully, New York. While the first and third datasets were taken horizontally, the second dataset was taken 20 degrees off-nadir to investigate the impact of oblique images. Results show that Pix4D and AgiSoft generate 2.5 times denser point clouds than DJI Terra. However, reconstruction quality evaluation using the Iterative Closest Point method (ICP) shows DJI Terra has fewer gaps in the point cloud and performed better than AgiSoft and Pix4D in generating a point cloud of trees, power lines and poles despite producing a fewer number of points. In other words, the outperformance in key points detection and an improved matching algorithm are key factors in generating improved final products. The computational time comparison demonstrates that the processing time for AgiSoft and DJI Terra is roughly half that of Pix4D. Furthermore, DSM elevation profiles demonstrate that the estimated height variations between the three software range from 0.5 m to 2.5 m. DJI Terra's estimated heights are generally greater than those of AgiSoft and Pix4D. Furthermore, DJI Terra outperforms AgiSoft and Pix4D for modeling the height contour of trees, buildings, and power lines and poles, followed by AgiSoft and Pix4D. Finally, in terms of the ability of tree detection, DJI Terra outperforms AgiSoft and Pix4D in generating a comprehensive DSM as a result of fewer gaps in the point cloud. Consequently, it stands out as the preferred choice for tree detection applications. The results of this paper can help 3D model users to have confidence in the reliability of the generated 3D models by comprehending the accuracy of the employed software.

Variable influence of photosynthetic thermal acclimation on future carbon uptake in Australian wooded ecosystems under climate change

Climate change will impact gross primary productivity (GPP), net primary productivity (NPP), and carbon storage in wooded ecosystems. The extent of change will be influenced by thermal acclimation of photosynthesis-the ability of plants to adjust net photosynthetic rates in response to growth temperatures-yet regional differences in acclimation effects among wooded ecosystems is currently unknown. We examined the effects of changing climate on 17 Australian wooded ecosystems with and without the effects of thermal acclimation of C3 photosynthesis. Ecosystems were drawn from five ecoregions (tropical savanna, tropical forest, Mediterranean woodlands, temperate woodlands, and temperate forests) that span Australia's climatic range. We used the CABLE-POP land surface model adapted with thermal acclimation functions and forced with HadGEM2-ES climate projections from RCP8.5. For each site and ecoregion we examined (a) effects of climate change on GPP, NPP, and live tree carbon storage; and (b) impacts of thermal acclimation of photosynthesis on simulated changes. Between the end of the historical (1976-2005) and projected (2070-2099) periods simulated annual carbon uptake increased in the majority of ecosystems by 26.1%-63.3% for GPP and 15%-61.5% for NPP. Thermal acclimation of photosynthesis further increased GPP and NPP in tropical savannas by 27.2% and 22.4% and by 11% and 10.1% in tropical forests with positive effects concentrated in the wet season (tropical savannas) and the warmer months (tropical forests). We predicted minimal effects of thermal acclimation of photosynthesis on GPP, NPP, and carbon storage in Mediterranean woodlands, temperate woodlands, and temperate forests. Overall, positive effects were strongly enhanced by increasing CO2 concentrations under RCP8.5. We conclude that the direct effects of climate change will enhance carbon uptake and storage in Australian wooded ecosystems (likely due to CO2 enrichment) and that benefits of thermal acclimation of photosynthesis will be restricted to tropical ecoregions.

Biotic interactions outweigh abiotic factors as drivers of bark microbial communities in Central European forests

Bark surfaces are extensive areas within forest ecosystems, which provide an ideal habitat for microbial communities, through their longevity and seasonal stability. Here we provide a comprehensive account of the bark surface microbiome of living trees in Central European forests, and identify drivers of diversity and community composition. We examine algal, fungal, and bacterial communities and their interactions using metabarcoding on samples from over 750 trees collected in the Biodiversity Exploratories in northern, central, and southern Germany. We show that mutual biotic influence is more important than the abiotic environment with regard to community composition, whereas abiotic conditions and geography are more important for alpha diversity. Important abiotic factors are the relative humidity and light availability, which decrease the algal and bacterial alpha diversity but strongly increase fungal alpha diversity. In addition, temperature is important in shaping the microbial community, with higher temperature leading to homogeneous communities of dominant fungi, but high turnover in bacterial communities. Changes in the community dissimilarity of one organismal group occur in close relation to changes in the other two, suggesting that there are close interactions between the three major groups of the bark surface microbial communities, which may be linked to beneficial exchange. To understand the functioning of the forest microbiome as a whole, we need to further investigate the functionality of interactions within the bark surface microbiome and combine these results with findings from other forest habitats such as soil or canopy.

Genetic diversity, gene flow, and landscape resistance in a pond-breeding amphibian in agricultural and natural forested landscapes in Norway

Genetic diversity is a key part of biodiversity, threatened by human activities that lead to loss of gene flow and reduction of effective population sizes. Gene flow is a result of both landscape connectivity and demographic processes determining the number of dispersing individuals in space and time. Thus, the effect of human impact on processes determining the level of genetic diversity must be interpreted in the context of basic ecological conditions affecting survival and recruitment. When the intensity of human impact and habitat suitability correlate, the effect on genetic diversity and gene flow may be challenging to predict. We compared genetic diversity, gene flow and landscape resistance in two contrasting landscapes in Norway for the pond-breeding amphibian Triturus cristatus: a highly human-impacted, agricultural landscape with ecologically productive habitats, and a forested landscape with less productive habitats and lower levels of human impact. Our results show that genetic diversity was higher and gene flow lower within the forested landscape. Microclimatic moisture conditions and vegetation cover were important determinants of landscape resistance to gene flow within both landscapes. There were indications that landscape resistance was increased by minor roads in the forested landscape, which was not the case for the agricultural landscape, suggesting a higher vulnerability to human interference within the landscape matrix for the populations in less productive habitats. Our findings suggest that the effect of human impact on genetic diversity may not be straightforward but modulated by the ecological conditions underlying local demographic processes. Populations within both landscapes seem to be vulnerable to loss of genetic diversity, but due to different mechanisms. This has implications for the choice of relevant management actions, that is, increasing population stability may be more relevant within an agricultural landscape still permeable for dispersal, while conserving dispersal corridors may be more appropriate in the forested landscape, to avoid isolation and increased genetic drift.

Agroforestry enhances biological activity, diversity and soil-based ecosystem functions in mountain agroecosystems of Latin America: A meta-analysis

Mountain agroecosystems in Latin America provide multiple ecosystem functions (EFs) and products from global to local scales, particularly for the rural communities who depend on them. Agroforestry has been proposed as a climate-smart farming strategy throughout much of the region to help conserve biodiversity and enhance multiple EFs, especially in mountainous regions. However, large-scale synthesis on the potential of agroforestry across Latin America is lacking. To understand the potential impacts of agroforestry at the continental level, we conducted a meta-analysis examining the effects of agroforestry on biological activity and diversity (BIAD) and multiple EFs across mountain agroecosystems of Latin America. A total of 78 studies were selected based on a formalized literature search in the Web of Science. We analysed differences between (i) silvoarable systems versus cropland, (ii) silvopastoral systems versus pastureland, and (iii) agroforestry versus forest systems, based on response ratios. Response ratios were further used to understand how climate type, precipitation and soil properties (texture) influence key EFs (carbon sequestration, nutrient provision, erosion control, yield production) and BIAD in agroforestry systems. Results revealed that BIAD and EFs related to carbon sequestration and nutrient provisioning were generally higher in agroforestry systems (silvopastoral and silvoarable) compared to croplands and pasturelands without trees. However, the impacts of agroforestry systems on crop yields varied depending on the system considered (i.e., coffee vs. cereals), while forest systems generally provided greater levels of BIAD and EFs than agroforestry systems. Further analysis demonstrated that the impacts of agroforestry systems on BIAD and EFs depend greatly on climate type, soil, and precipitation. For example, silvoarable systems appear to generate the greatest benefits in arid or tropical climates, on sandier soils, and under lower precipitation regimes. Overall, our findings highlight the widespread potential of agroforestry systems to BIAD and multiple EFs across montane regions of Latin America.

Halyomorpha halys (Hemiptera: Pentatomidae) trap captures at orchard and nonorchard sites and the influence of uncultivated woody host plants in adjoining woodlots

The invasive Halyomorpha halys (Hemiptera: Pentatomidae) has threatened Mid-Atlantic tree fruit since 2010. To identify factors underlying observed differences in H. halys pest pressure among individual orchards within a geographically proximate area, a 3-yr study was conducted across 10 apple orchard and 8 nonorchard sites bordered by unmanaged woodlots. At each site, 3 pheromone traps were monitored weekly for H. halys captures from late April to mid-October. Apple injury was assessed at harvest at orchard sites annually, and a survey of woody plants found in woodlots adjacent to all sites was conducted. There were no significant differences in captures between orchard and nonorchard site types, but captures were significantly different among individual orchard sites and among individual nonorchard sites. A significant positive relationship between the amount of stink bug injury on apple at harvest and late season captures was detected at orchard sites in 2018 and 2019. Among woodlots adjacent to all sites, a significant positive relationship between the proportion of Lonicera spp. and mid- and late-season nymphal captures was identified. Season-long nymphal captures were positively related to the proportion of Lonicera and Elaeagnus and negatively with Sassafras. For adults, captures were negatively related to the proportion of Ailanthus and positively related to the proportion of Fraxinus in the early and mid-season, respectively. Our results indicate that orchard presence was not driving the relative abundance of localized H. halys populations and that differences in relative densities among sites point to other factors, such as abundance of specific uncultivated woody hosts in unmanaged areas.

Diameter, height and species of 42 million trees in three European landscapes generated from field data and airborne laser scanning data

Ecology and forestry sciences are using an increasing amount of data to address a wide variety of technical and research questions at the local, continental and global scales. However, one type of data remains rare: fine-grain descriptions of large landscapes. Yet, this type of data could help address the scaling issues in ecology and could prove useful for testing forest management strategies and accurately predicting the dynamics of ecosystem services. Here we present three datasets describing three large European landscapes in France, Poland and Slovenia down to the tree level. Tree diameter, height and species data were generated combining field data, vegetation maps and airborne laser scanning (ALS) data following an area-based approach. Together, these landscapes cover more than 100 000 ha and consist of more than 42 million trees of 51 different species. Alongside the data, we provide here a simple method to produce high-resolution descriptions of large landscapes using increasingly available data: inventory and ALS data. We carried out an in-depth evaluation of our workflow including, among other analyses, a leave-one-out cross validation. Overall, the landscapes we generated are in good agreement with the landscapes they aim to reproduce. In the most favourable conditions, the root mean square error (RMSE) of stand basal area (BA) and mean quadratic diameter (Dg) predictions were respectively 5.4 m 2.ha -1 and 3.9 cm, and the generated main species corresponded to the observed main species in 76.2% of cases.

Improving climate and biodiversity outcomes through restoration of forest integrity

Targeting degraded areas in forested landscapes for restoration could deliver rapid climate mitigation and biodiversity conservation, improve resilience of forested lands to future climate change, and potentially reduce the trade-offs between nature recovery and agriculture. Although the importance of forest restoration for climate mitigation is acknowledged, current estimates of its climate mitigation potential may be underestimated because they focus predominantly on reforesting cleared areas. We built on recent analyses of forest integrity and unrealized forest biomass potential to examine the potential for restoring the integrity of degraded forests. There are over 1.5 billion ha of forests worldwide that retain 50-80% of their potential biomass. Prioritizing restoration in these areas could deliver rapid biodiversity and climate mitigation benefits, relative to restoring forest on cleared land. We applied a spatial planning approach to demonstrate how restoration interventions can be targeted to support the conservation of high-integrity forest, a potential pathway to the delivery of the 30×30 goal of the Convention on Biodiversity's Global Biodiversity Framework.

Impacts of Lithology and Slope Position on Arbuscular Mycorrhizal Fungi Communities in a Karst Forest Soil

The influence of lithology and slope position on arbuscular mycorrhizal fungi (AMF) communities has been explored in various ecosystems, but there is a limited understanding of these mechanisms in karst regions. This study focused on typical karst hills with contrasting lithologies, specifically dolomite and limestone. Additionally, three slope positions (upper, middle, and lower) were investigated within each hill in karst forest ecosystems. Total phosphorus (TP) content in the soil was higher in dolomite compared to limestone. Conversely, exchangeable calcium (Ca) was lower in dolomite than in limestone. Notably, the lithology, rather than the slope position, exerted a significant impact on AMF diversity and abundance and the presence of specific AMF taxa. Dolomite exhibited greater AMF richness and a higher Shannon index in comparison to limestone when not accounting for slope position. The AMF community composition differed between dolomite and limestone. For instance, without considering slope position, the relative abundance of Acaulospora, Diversispora, and Paraglomus was higher in dolomite than in limestone, while the relative abundance of Claroideoglomus displayed an opposing trend. Furthermore, a more complex interaction among AMF taxa was observed in dolomite as compared to limestone, as evidenced by an increase in the number of nodes and edges in the co-occurrence networks within the dolomite. The genera Glomus, Claroideoglomus, and Diversispora exhibited a higher number of links with each other and with other AMF taxa. The study identified TP and Ca as the primary factors determining variations in AMF diversity between dolomite and limestone. Consequently, it is imperative to consider the underlying lithology and soil conditions when addressing the restoration of degraded karst hilly areas.

First report of Diplodia quercivora causing branch cankers on declining chestnut oak (Quercus montana) in Virginia

Since the beginning of the twentieth century oak decline has been documented in central and eastern hardwood forests of the United States as a stress-mediated disease (Oak et al. 2016). Opportunistic canker pathogens, including Diplodia corticola, D. quercivora, D. sapinea, and Botryosphaeria dothidea have been associated with crown dieback of declining oak trees in several mid-Atlantic states (Ferreira et al. 2021). On 02 August 2022, a survey was conducted at two natural hardwood sites in Fredrick and Shenandoah Counties, Virginia that exhibited symptoms of decline (Fig. 1A). At both sites, mature Quercus montana trees were observed with bole and branch cankers, bleeding and sooty lesions, and discolored sapwood. Pycnidia were present on the margin of seven branch cankers from three trees that were felled, with hyaline, elliptical to oblong conidia 19.0 - 26.8 × 8.5 - 11.2 µm (n = 40) in size (Fig. 1C and D). Six cultures were derived from single spores that were placed on PDA medium and incubated for 10 days in the dark at 22 ± 2°C. Additionally, a 4-mm piece of necrotic tissue was selected from the margin of each of the seven cankers, disinfected with 2.5% NaOCl, again with 70% ethanol, and air-dried before being placed on half-strength acidified PDA medium (pH 4.8) and incubated in the dark at 22 ± 2°C. After 5 days, seven colonies from each canker assayed were transferred to full-strength PDA plates and incubated for 10 days in the dark at 22 ± 2°C. Colonies derived from spores and the necrotic wood were morphologically identical, with white, aerial, floccose mycelium that turned dark gray to olivaceous after five days (Fig. 1B). DNA was individually extracted from four, 10-day-old cultures (two from spores and two from wood). Mycelia was harvested with a sterile pin and extracted using a Qiagen DNeasy Plant Pro Kit (Germantown, MD) according to the manufacturer's instructions. A segment of the internal transcribed spacer (ITS), large subunit rRNA (LSU), and translation elongation factor 1-α (tef1) loci were amplified using ITS4/ITS5 (White et al. 1990), LR5/LROR (Vilgalys and Hester 1990), and EF1-728F/EF1-986R (Carbone and Kohn 1999) primer sets, respectively. The PCR amplicons were purified with ExoSap-IT (Affymetrix, Santa Clara, CA) and sequenced at Eurofins (Louisville, KY). The nucleotide sequences were analyzed using Geneious 11.1.5 software (Biomatters, Auckland, NZ). The resulting ITS sequences from the four isolates were identical. A 544-bp, 1131-bp, and 273-bp segment of the ITS, LSU, and tef1 loci from isolate GS22-DSB-17 was deposited into the GenBank database (accessions OQ597712, OQ597714, and OR754429, respectively). A Genbank BLAST analysis revealed that the ITS and tef1 fragments shared 510/516 (99%) and 271/273 (99%) nucleotides with the D. quercivora ex-type BL8 (JX894205/JX894229). Koch's postulates were fulfilled by inoculating five healthy, containerized Q. montana trees (average stem caliper 6.5 cm) with D. qercivora isolate GS22-DSB-17, while five plants were used as controls. After disinfecting the bark with 70% ethanol, a 0.5 mm section of the bark was removed 13 cm above the soil line with a sterile scalpel, and a 0.5 mm agar plug taken from the edge of a 10-day-old PDA culture was placed in the wound with the mycelium facing the cambial tissue, sealed with Parafilm, and maintained at 22 ± 6°C. The same procedure was performed on the control plants using sterile PDA plugs. After six weeks the bark was carefully removed, and all five stems treated with D. quercivora had necrotic lesions with a mean canker linear growth ([length+width]/2) of 15.6 mm from the edge of the wound, which was significantly larger (P = 0.001) than the controls (2.3 mm; Fig. 1E-M). Necrotic stem tissue was sampled as previously described, and the isolate recovered was confirmed as D. quercivora based on morphology and 100% ITS sequence homology to isolate GS22-DSB-17. D. quercivora was not recovered from the control plants. In the United States, D. quercivora has been isolated from declining white oak trees in Maryland, Massachusetts, West Virginia, and Florida (Dreaden et al. 2014; Ferreira et al. 2021; Haines et al. 2019). More surveys are needed to understand the host range and distribution of D. quercivora in the United States, as well as the environmental and site factors that impact oak health and predispose trees to infection from opportunistic cankering pathogens.

A demo-genetic model shows how silviculture reduces natural density-dependent selection in tree populations

Biological production systems and conservation programs benefit from and should care for evolutionary processes. Developing evolution-oriented strategies requires knowledge of the evolutionary consequences of management across timescales. Here, we used an individual-based demo-genetic modelling approach to study the interactions and feedback between tree thinning, genetic evolution, and forest stand dynamics. The model combines processes that jointly drive survival and mating success-tree growth, competition and regeneration-with genetic variation of quantitative traits related to these processes. In various management and disturbance scenarios, the evolutionary rates predicted by the coupled demo-genetic model for a growth-related trait, vigor, fit within the range of empirical estimates found in the literature for wild plant and animal populations. We used this model to simulate non-selective silviculture and disturbance scenarios over four generations of trees. We characterized and quantified the effect of thinning frequencies and intensities and length of the management cycle on viability selection driven by competition and fecundity selection. The thinning regimes had a drastic long-term effect on the evolutionary rate of vigor over generations, potentially reaching 84% reduction, depending on management intensity, cycle length and disturbance regime. The reduction of genetic variance by viability selection within each generation was driven by changes in genotypic frequencies rather than by gene diversity, resulting in low-long-term erosion of the variance across generations, despite short-term fluctuations within generations. The comparison among silviculture and disturbance scenarios was qualitatively robust to assumptions on the genetic architecture of the trait. Thus, the evolutionary consequences of management result from the interference between human interventions and natural evolutionary processes. Non-selective thinning, as considered here, reduces the intensity of natural selection, while selective thinning (on tree size or other criteria) might reduce or reinforce it depending on the forester's tree choice and thinning intensity.

Rapid New Diagnostic LAMP (Loop-Mediated Isothermal Amplification) Assays to Distinguish Among the Four Lineages of Phytophthora ramorum

Sudden oak death (SOD) is caused by Phytophthora ramorum, an invasive oomycete pathogen. This pathogen is of major regulatory concern for nurseries, horticulture, and forestry in the United States and around the world. Three of the 12 identified lineages of P. ramorum currently occur in the United States (NA1, NA2, and EU1) affecting wildland forests and nurseries. Rapid identification and lineage determination is essential to accelerate management decisions, detect introductions of new lineages, and control the spread of SOD. The objective of this study was to develop and validate diagnostic tools to rapidly identify P. ramorum and distinguish among the four common lineages of the pathogen and to accelarate management decision making. The loop-mediated isothermal amplification (LAMP) assays developed here are species specific with no cross reaction to common Phytophthora species found in Oregon, California, and Washington. The lineage-specific assays unambiguously distinguish among the four common clonal lineages. These assays are sensitive and able to detect P. ramorum DNA ranging in concentration from 30 to 0.03 ng/μl depending on the assay. These assays work effectively on a variety of sample types including plant tissue, cultures, and DNA. They have been integrated into the SOD diagnostic process in the forest pathology lab at Oregon State University. To date, 190 samples have been correctly identified from over 200 field samples tested for lineage determination. The development of these assays will help managers in forestry and horticulture identify and rapidly respond to new outbreaks of P. ramorum.

Lutein and Zeaxanthin Content in 21 Plant Species from a Very Humid Premontane Forest in Colombia Palatable for Free-Range Laying Hens

Xanthophylls, such as lutein and zeaxanthin, have several functions in both plants and humans, including detoxification of oxidants (reactive oxygen species (ROS) and other radicals), maintenance of the structural and functional integrity of biological membranes, and photoprotection from intense light damage. The objective of the present study was to investigate the lutein and zeaxanthin content of 21 species of plants from a very humid premontane forest in Colombia during both dry and rainy seasons. The plants were selected based on being voluntarily eaten by laying hens under free-range conditions. Lutein and zeaxanthin were identified and quantified by high-performance liquid chromatography (HPLC). The results showed that all plants tested contained lutein, at levels ranging from 65.7 to 350 µg/g. Zeaxanthin levels were much lower (2.2 to 26.2 µg/lg) and were detected in only 5 of the 21 plants analyzed. Given that the lutein content of the plants tested in the present study was found to be comparable to that reported in marigold flowers (4-800 µg/g), it is possible that these plants can be used as a source of lutein in free-range laying hen production systems.

Long-term mitigation of drought changes the functional potential and life-strategies of the forest soil microbiome involved in organic matter decomposition

Climate change can alter the flow of nutrients and energy through terrestrial ecosystems. Using an inverse climate change field experiment in the central European Alps, we explored how long-term irrigation of a naturally drought-stressed pine forest altered the metabolic potential of the soil microbiome and its ability to decompose lignocellulolytic compounds as a critical ecosystem function. Drought mitigation by a decade of irrigation stimulated profound changes in the functional capacity encoded in the soil microbiome, revealing alterations in carbon and nitrogen metabolism as well as regulatory processes protecting microorganisms from starvation and desiccation. Despite the structural and functional shifts from oligotrophic to copiotrophic microbial lifestyles under irrigation and the observation that different microbial taxa were involved in the degradation of cellulose and lignin as determined by a time-series stable-isotope probing incubation experiment with 13C-labeled substrates, degradation rates of these compounds were not affected by different water availabilities. These findings provide new insights into the impact of precipitation changes on the soil microbiome and associated ecosystem functioning in a drought-prone pine forest and will help to improve our understanding of alterations in biogeochemical cycling under a changing climate.

Impacts of environmental decontamination on the rebuilding of returnees' lives after the Fukushima accident

Environmental decontamination after a nuclear disaster not only contributes to reducing the public's exposure to radiation, it also introduces waste disposal issues arising from the decontamination process. In addition to that issue, the optimisation of decontamination efforts necessitates the consideration of various environmental, economic, and societal factors. Stakeholders' perspectives are important for identifying the multifaceted aspects to be considered. We conducted a semi-structured interview survey in 2019 with ten residents in a rural community in Fukushima, Japan, which experienced a six-year-long evacuation due to the 2011 Fukushima Daiichi Nuclear Power Plant accident. The main survey questions addressed returnees' perceptions of the decontamination of farmlands and forests. The 'Steps for Coding and Theorization' procedure was used for qualitative analysis. The analysis illuminated the positive and negative impacts of the decontamination process on the rebuilding of the returnees' rural lives from various perspectives and identified elements to be considered for the optimisation of future remediation efforts. The removal of radioactive materials had a positive psychological impact on the returnees, fostering a sense of security that their crops were safe and instilling confidence that the high-quality environment of the region had been restored. These aspects were not included among the initial governmental objectives for decontamination, which were aimed solely at reducing radiation exposure. By contrast, the removal of fertile topsoil from farmland had a negative impact on the residents, making them hesitant to resume farming. Our findings suggest that emphasising procedural fairness in decision-making of decontamination options such as reflection of stakeholders' opinions led to residents perceiving their post-decontamination situation more positively. Our results provide valuable insights for optimising remediation strategies for the recovery process following a significant nuclear accident.

First report of Leaf Blight of Liquidambar formosana Hance caused by Alternaria tenuissima in China

Liquidambar formosana Hance is widely planted in urban landscapes in China owing to its ornamental red leaves. In June 2020, a distinctive leaf spot disease was observed on L. formosana in Nanjing Forestry University, Jiangsu Province of China (32°4'49"N, 118°48'56"E). Approximately 61% (14 out of 23) of the trees displayed leaf spots. The diseased symptoms included irregularly distributed spots that showed black or dark brown, and occasionally with pale green halo. Two representative trees were selected for sampling and five leaves with typical symptoms were selected randomly for isolation. The tissues from the margin of the lesions (0.2 cm × 0.2 cm) were cut and disinfected in 1% sodium hypochlorite for 90 s, rinsed in sterile water twice for 30 s, and dried with sterile paper. Then, 20 tissues were incubated on 2% potato dextrose agar (PDA) supplemented with 100 mg/L Ampicillin Sodium and incubated in the dark at 25℃ for 4 days. Seventeen single-spore fungi were isolated from lesion tissues as described by Woudenberg et al. (2013). The colony morphology of 17 isolates was extremely similar, so 3 isolates (NFUA01, NFUA02, and NFUA03) were selected randomly for further study. Colonies on PDA were circular, gray, and slightly raised loose cotton mycelium, while the reverse side was olive green in the center with white margins. Conidiophores were brown, simple or branched, and produced numerous conidia in short chains. Conidia were obclavate or ellipsoid, brown, with 1-5 transverse septa and 0-3 longitudinal septa, and measured 7.1 to 32.5 × 3.3 to 13.3 μm (n=50). The morphological observations were consistent with the description of the genus Alternaria sp. (Woudenberg et al. 2013). Six gene fragments, including SSU, LSU, ITS, GAPDH, RPB2 and EF-1 region, were amplified and sequenced. The primers of six nuclear loci were used by NS1 / NS4((White et al. 1990), LSU1Fd (Crous et al. 2009)/ LR5 (Vilgalys & Hester 1990), V9G (De Hoog & Gerrits van den Ende 1998)/ ITS4 (White et al. 1990), gpd1 / gpd2 (Berbee et al. 1999), RPB2-5F2 / fRPB2-7cR (Liu et al. 1999), and EF1-728F / EF1-986R (Carbone & Kohn 1999). The sequences were submitted in GenBank (SSU, ON237470 to ON237472; LSU, ON237464 to ON237466; ITS, ON197354 to ON197356; GAPDH, ON237476 to ON237478; RPB2, ON237467 to ON237469; EF-1, ON237473 to ON237475). BLAST result showed that SSU, LSU, ITS, GAPDH, RPB2, and EF-1 sequences of NFUA01, NFUA02, and NFUA03 were identical to A. tenuissima at a high level (>99%, Table 1). A maximum likelihood and Bayesian posterior probability analysis were performed by IQtree v. 1.6.8 and Mr. Bayes v. 3.2.6 with the concatenated sequences (Guindon et al. 2010; Ronquist et al. 2012). The representative strains which selected for Phylogenetic analyses were chosen from the strains which mentioned by Woudenberg et al (2013) and obtained the sequences from NCBI. The concatenated sequences placed NFUA01, NFUA02 and NFUA03 in the clade of Alternaria tenuissima with a high confidence level (ML/BI= 100/1). A pathogenicity assay was done using isolate NFUA01 on 3-year-old L. formosana seedlings. L. formosana leaves were wounded by a sterilized needle (0.5-mm-diam), and inoculated with spore suspension (106 conidia/mL), and L. formosana leaves inoculated with sterile water were used as the control. Each treatment had 5 leaves, and incubated at 25℃ under high moisture conditions. The experiments were conducted three times. Seven days after inoculation, leaves inoculated with spore suspension showed brown leaf blights resembling the original disease symptoms, whereas the control remained healthy. The fungus was reisolated from the lesions and was confirmed as A. tenuissima based on morphologically characteristics and ITS sequence analysis. To our knowledge, this is the first report of A. tenuissima associated with leaf blight on L. formosana. The finding provides clear pathogen information for further evaluation of the disease control strategies.

Seasonal Hydration Status of Common Bryophyte Species in Azorean Native Vegetation

Bryophytes play a crucial role in the ecosystem's water compartment due to their unique ability to retain water. However, their role within temperate native ecosystems is mostly unknown. To address this knowledge gap, a study was conducted on Terceira Island (Azores), focusing on 14 bryophyte species found at different altitudes (40 m, 683 m, and 1012 m); five samples were collected monthly, per species and location, and their fresh, saturated, and dry weights were examined in the laboratory; four species were collected from more than one site. Generalized linear models (GLM) were used to assert the influence of climate factors (temperature, precipitation, and relative humidity) and environmental variables on two water indicators: field water content (FWC) and relative water content (RWC). None of the examined factors, per se, were able to explain all cases. Species appear to respond to climate according to a limiting factor effect: at lower elevations, precipitation was determinant, while at medium elevations, FWC was influenced by a combination of precipitation and relative humidity. At higher elevations, temperature was retained for seven of the nine studied species. The RWC values indicated that the 14 bryophyte species remained hydrated throughout the year but rarely reached their maximum water-holding capacity, even at the highest altitude. Understanding the mechanisms by which native bryophytes acquire, store, and release water is crucial for comprehending the resilience of native vegetation in the face of climate change. This knowledge can also enable the development of strategies to mitigate the effects of climate change and protect vital water resources.

First report of Bot Canker (Diplodia corticola) in Pin Oak (Quercus palustris) in Tennessee

Diplodia corticola is a fungal pathogen contributing to oak (Quercus spp.) decline in the Mediterranean and US (Félix et al., 2017; Ferreira et al., 2021). In 2021, this pathogen was detected in Tennessee (TN) causing branch dieback in Q. alba (Onufrak et al., 2022). In September 2021, a matured pin oak (Q. palustris) with wilted leaves and elongated branch cankers was observed in the State Botanical Garden of Tennessee-Knoxville (TN, US). Small sections of the phloem were sampled from canker margins of a symptomatic branch using a sterile scalpel, surface sterilized, and plated onto potato dextrose agar amended with antibiotics (PDA++) (Gazis et al. 2018). Three days later, a fungal isolate resembling D. corticola was cultured on ½ PDA. Diplodia corticola is characterized on half-strength PDA by fast growth, irregular margins, and dense white mycelium that turns dark, grayish as the mycelium matures (Úrbez-Torres et al., 2010; Alves et al., 2004). Total genomic DNA was extracted from this isolate following Gazis et al. (2018), and the internal transcribed spacer (ITS), large ribosomal subunit (LSU), and transcription elongation factor 1-α (ef1-α) were amplified (Ferreira et al. 2021). Resulting PCR products were sequenced and assembled into consensus sequences using Unipro UGENE v. 44.0 (Okonechnikov et al., 2012). Each consensus sequence identity was determined using BLAST on the NCBI nucleotide database, restricted to type material. The ITS (accession OQ189888), ef-1α (accession OQ201608), and LSU (accession OQ189887) sequences had a 99.6% (accession KF766156.1), 98.6% (accession XM_020275852.1), and 100% (accession KF766323.1) identity match with D. corticola type culture CBS112549, respectively. To complete Koch's postulates and assess potential pathogenicity on economically and ecologically relevant oaks, 10 pin (Q. palustris; caliper 15.6 ± 2.0 mm), 10 overcup (Q. lyrata; caliper 15.1 ± 2.4 mm), and 10 sawtooth (Q. acutissima; 16.1 ± 2.1 mm) oaks were acclimated in the greenhouse for 1 week prior to the experiment. Five trees of each species were then randomly inoculated at 30 cm above the soil line with a 3 mm diameter plug of D. corticola (grown for 10 days on PDA; Sitz et al. 2017). To serve as a control, the remaining 5 trees for each species received a 3 mm diameter PDA plug. Fifteen days post-inoculation, seepage was observed in D. corticola-inoculated pin (5/5 trees), overcup (4/5 trees), and sawtooth (4/5 trees) oaks. No seepage from wound sites was noted in control trees. Cankers were exposed, photographed, and then measured using ImageJ (Rasband, 2012). Using a sterile scalpel, four wood chips were excised from canker margins and plated onto PDA++. We recovered D. corticola from symptomatic inoculated pin (5/5 trees), overcup (4/5 trees), and sawtooth (4/5 trees) oaks and confirmed species identity by extracting DNA and amplifying the ITS, ef-1α, and LSU regions as described above (Gazis et al., 2018; Ferreira et al., 2021). The resulting consensus sequences matched the D. corticola type culture (CBS112549) ITS (99.0%-99.8% identity), ef-1α (91.0%-99.1% identity), and LSU (96.9%-100% identity) barcoding regions. Cankers were significantly larger in D. corticola-inoculated pin (4.7 ± 1.5 cm2; P = 0.003), overcup (6.8 ± 2.9 cm2; P = 0.009), and sawtooth (5.1 ± 1.3 cm2; P = 0.001) oaks in comparison to the control trees from these groups. Based on current reports, this is the first record of D. corticola causing dieback in pin oak (Q. palustris) in TN.

Molecular Population Genetics of Aspen Mosaic-Associated Virus in Finland and Sweden

Aspen mosaic-associated virus (AsMaV) is a newly identified Emaravirus, in the family Fimoviridae, Bunyavirales, associated with mosaic symptoms in aspen trees (Populus tremula). Aspen trees are widely distributed in Europe and understanding the population structure of AsMaV may aid in the development of better management strategies. The virus genome consists of five negative-sense single-stranded RNA (-ssRNA) molecules. To investigate the genetic diversity and population parameters of AsMaV, different regions of the genome were amplified and analyzed and full-length sequence of the divergent isolates were cloned and sequenced. The results show that RNA3 or nucleoprotein is a good representative for studying genetic diversity in AsMaV. Developed RT-PCR-RFLP was able to identify areas with a higher number of haplotypes and could be applied for screening the large number of samples. In general, AsMaV has a conserved genome and based on the phylogenetic studies, geographical structuring was observed in AsMaV isolates from Sweden and Finland, which could be attributed to founder effects. The genome of AsMaV is under purifying selection but not distributed uniformly on genomic RNAs. Distant AsMaV isolates displayed amino acid sequence variations compared to other isolates, and bioinformatic analysis predicted potential post-translational modification sites in some viral proteins.

Spore Dispersal Patterns of Colletotrichum fioriniae in Orchards and the Timing of Apple Bitter Rot Infection Periods

Bitter rot is a major disease of apple fruit in warm and humid regions. It is caused by various species in the Colletotrichum gloeosporioides and C. acutatum species complexes, of which C. fioriniae of the C. acutatum species complex is most common in the Mid-Atlantic region of the United States. While bitter rot management begins with good cultural practices, fungicides are generally used for consistent control. Fungicides should be applied before or during infection periods, but the timing of infection is unclear due to the hemibiotrophic lifestyle of the causal species. To determine when infection periods occur, we quantified C. fioriniae spore dispersal throughout three growing seasons and compared the temporal susceptibility of apples in two seasons of field trials. Spores were detected in rainwater from bud break to leaf drop, with the highest spore quantities in the summer and early fall correlating with optimal temperatures for C. fioriniae. Late-season-inoculated fruit had more bitter rot than early-season-inoculated fruit, but this was also positively correlated with periods of optimal temperatures and moisture for infection. In the context of previous experiments, these results suggest that infection periods are primarily determined by temperature and moisture rather than apple fruit phenology. Based on the relative numbers of spores and biotrophic and necrotrophic infections, only a tiny proportion of spores establish viable biotrophic infections, but a relatively high proportion of biotrophic infections switch to necrotrophy. We suggest bitter rot management should focus on preventing initial biotrophic infections by protecting apples during weather conditions that favor infection.

First Report of Root Rot Caused by Phytophthora lacustris on alder (Alnus lusitanica) in Spain

Alder decline caused by Phytophthora species is considered one of Europe´s most important diseases of natural ecosystems. In Spain, P. x alni, P. uniformis, P. x multiformis and P. plurivora have been detected in association with root and collar rot in riparian alder populations (Pintos et al. 2010, 2012, 2017; Haque et al. 2014). During the active growth periods 2020-2021, a field survey of the newly designed species Alnus lusitanica (Vít et al. 2017) was carried out at the most symptomatic areas along the Miño-Sil river basin in Galicia and León (NW-Spain). Samples of bark, root, rizosphere soil of declining trees, and river water were collected. Symptoms, similar to those caused by other Phytophthora species, included low leaf density of the canopy, generally with smaller and chlorotic leaves, and branches with dry tips. In some cases, the presence of cankers on the trunk were observed (Figure 1). Necrotic lesions were transferred onto V8-PARPH, a Phytophthora selective medium. Soil and water were baited with carnation petals. Three isolates of one Phytophthora species was recovered: two from the roots of trees, and one from river water at three different sites. The isolates were transferred to V8 agar and incubated a 22ºC in the dark. Colonies had petaloid patterns, and their optimum growth temperature ranged from 25 to 30 °C. In soil extract, non-caducous, non-papillate and ovoid sporangia were produced. Sporangia averaged 41.0×29.4 μm with a length/breadth ratio of 1.39. Internal proliferation occurred (Figure 2). No sexual structures were observed . Genomic DNA was extracted from mycelium obtained from pure cultures of three Phytophthora isolates. The ITS region of the ribosomal DNA template was performed by nested PCR using DC6 (Cooke et al. 2000) and ITS4 (White et al. 1990) in the first round, and ITS6 (Cooke et al. 2000) and ITS4 in the second. The mitochondrial gene cox1 was amplified with primers CoxF4N and CoxR4N (Kroon et al. 2004). BLASTn analyses showed 100% identity to the type of P. lacustris (AF266793, 156 matching bp) for ITS, and 100% identity to the ex-type of P. lacustris (MH136916, 596 matching bp) for the cox1 sequence. Phylogenetic analysis indicated that our isolates were localized in the same evolutionary branch as P. lacustris based on consense sequences of ITS and cox1 sequences. The ITS and cox1 sequences generated in this study were deposited in GenBank with accession number OP588369 and OP548051, and one isolate isolated from root (CECT 21212) was submitted to the Spanish Type Culture Collection (Paterna, Valencia). Pathogenicity tests with isolate CECT 21212 were conducted on ten 3-year-old alders (A. lusitanica) growing in free draining 5 L pots. One shallow cut was made into the cambium at the root collar level. A colonized 5-mm mycelial agar plug, from a 7-day-old culture was inserted into every wound (mycelial surface face-down) and sealed with Parafilm®. Five control plants were inoculated with a sterile agar plug. Plants were kept in a controlled chamber at 25 ºC and 80% humidity. After a 3-week incubation period, inoculated plants showed dieback symptoms and necrosis of the inner bark tissue (Figure 3). Lesion lengths ranged from 2 to 8 cm. Control plants remained symptomless. P. lacustris was recovered from all inoculated plants, but not from the control ones. To our knowledge, this is the first report of P. lacustris causing root rot on alders in Spain. This new detection represents an increased threat to riparian alders by the presence of an additional Phytophthora species associated with alder decline, since P. lacustris can readily adapt to a wide variety of climatic conditions with the ability to infect different hosts (Nechwatal et al. 2013).

Effects of season of fire on bee-flower interaction diversity in a fire-maintained pine savanna

Whereas the Coastal Plain of the southeastern United States historically experienced fire primarily during the mid-summer lightning season, managers today typically apply prescribed fire during the late winter or early spring months. The ecological implications of this discrepancy remain poorly understood, especially with regard to pollinators and their interactions with flowers. In a replicated field experiment, we compared the abundance and richness of bees and bee-flower interactions among pine savanna plots in Florida that were burned either during the winter, spring, summer, or fall. We netted 92 bee species from 77 species of flowers, representing 435 unique bee-flower interactions in total. When analyzing the results from each month separately, we detected significant short-term reductions in the number of bees and bee-flower interactions following fires regardless of season. Although bee abundance and richness did not differ over the entire season, bee-flower interaction richness was significantly higher overall in spring and summer plots than in fall plots and the composition of both bees and bee-flower interactions differed significantly among treatments. Several bee-flower interactions were significantly associated with one or more of the treatments. Some of these associations could be attributed to differences in flowering phenology among treatments. Taken together, our findings suggest that season of fire has modest but potentially important implications for interactions between bees and flowers in southeastern pine ecosystems. Because most flowering plants within our study region are pollinated by a variety of bees and other insects, and most bees endemic to the region are polylectic, season of fire may not be very important to either group overall. However, the timing of fire may be more important to particular species including certain flower specialists and fire-sensitive taxa such as butterflies. Future research targeting such species would be of interest.

First report of Didymella glomerata causing leaf spot on Lonicera caerulea L. in Heilongjiang province, China

China has the largest blue honeysuckle (Lonicera caerulea L.) cultivation area globally. In June 2022, leaf spots were observed on approximately 10% of blue honeysuckle (cv. 'Lanjingling') leaves in a 0.03-ha field in Harbin (127.66°E, 45.61°N), Heilongjiang Province, China. The leaves of the affected plants displayed chlorotic to tan dieback with a darker brown margin along the leaftip and leave margins. Cross-sectional segments of approximately 3 mm were cut from 50 typical infected plant leaves. Their surfaces were sterilized with 75% ethanol for 30 s followed by 3 min in 5% sodium hypochlorite (NaOCl), rinsed three times with sterile water, and transferred to 9-cm Petri dishes containing 15 ml of sterile PDA growth medium. Five purified cultures with similar culture characteristics were finally obtained and their colonies were dark brown on the PDA plates. The pycnidia were subglobular and deep black and measured avg. 215.48 (135.30-331.20) μm × avg. 170.28 (99.90-282.90) μm (n = 50) (Chen et al., 2015; Huang et al., 2018). Conidia were single-celled, hyaline, and ellipsoidal and measured avg. 6.22 (5.40-7.20) µm × avg. 3.42 (2.70-3.90) µm (n = 50). For molecular verification, genomic DNA was extracted from a representative isolate, LD-75. The internal transcribed spacer region (ITS), the second-largest subunit of RNA polymerase II (rpb2), the partial 28S large subunit rDNA (LSU), beta-tubulin (TUB), and actin (ACT) genes were amplified with the primers ITS1/ITS4, RPB2f/RPB2r, LROR/LR7, TUB2Fd/TUB4Rd, and ACT512f/ACT783R, respectively (White et al. 1990; Carbone and Kohn, 1999; Staats et al., 2005; de Gruyter et al., 2009; Chen et al., 2015). BLAST results indicated that the genes of LD-75 (GenBank OP218870, OP264863, OQ561448, OQ597233, and OQ597232) shared 99%-100% identity with those of Didymella glomerata (OK485138, GU371781, EU754185, MZ073910, and MW963190, respectively). Therefore, based on morphological characteristics and molecular phylogeny, LD-75 was identified as D. glomerata. Six two-year-old healthy plants from the 'Lanjingling' cultivar were selected for a pathogenicity test. The leaves were surface disinfested with 75% ethanol and then wiped with sterilized water three times. All plants were cultured in a greenhouse at 28℃ under a 12-h light/dark cycle. Whole plants sprayed with conidial suspension of isolate LD-75 (106 spores/mL) (n = 3) displayed leaf spot symptoms after 14 d, while no symptoms were detected on whole plants sprayed with sterile water (n = 3). The same isolate, reisolated from infected leaves and with the same morphological and molecular traits, was also identified as D. glomerata, confirming Koch's postulate. The fungus was previously reported in Cornus officinalis in Nanyang City, China (Huang et al., 2018). To our knowledge, this is the first report of blue honeysuckle leaf spot caused by D. glomerata in China. Reducing blue honeysuckle production losses caused by leaf spots is crucial for growers, and we hope that researchers will develop efficient control strategies for managing this emerging plant disease.

First report of Colletotrichum fioriniae Causing Anthracnose Disease of Rhus chinensis in China

Rhus chinensis, a tree of major economic importance in China, belongs to the Anacardiaceae. It is the summer host of the aphid Melaphis chinensis which produces a leaf gall utilized for medicinal purposes (Li et al. 2022). In August 2021 and June 2022, dark brown spots were observed on young branches of R. chinensis in Wufeng, Hubei province, China. The plantations of R. chinensis in Wufeng County had different degrees of disease. We focused our survey on three plantations, each with an area of 1.5 hectares and 1600 R. chinensis plants per hectare, and the incidence of the disease was found to be around 70%. Symptoms began as small brown spots that expanded with time and eventually led to large, irregular, dark brown and sunken lesions. Under high temperature and humidity, orange conidiomata appeared on top of the lesions. As the disease progressed, branches rotted, broke, and leaves died and dropped, eventually causing the death of trees. The fungus was isolated from infected branches. Branch pieces were cut and surface disinfested in 75% (v/v) alcohol for 30 sec, then sterilized in 4% sodium hypochlorite for 1 min, and washed three times with sterile distilled water before incubated on potato dextrose agar (PDA) at 25℃.Ten isolates were obtained by a single-spore culturing method, considering HTK-3 isolate showed more pathogenic and grew faster than other isolates, it was selected for further research. After culturing for 7 days on PDA medium, the colony of isolate HTK-3 was cottony with white-to-gray aerial mycelium. The mycelial growth rate was 8.7 mm/day at 25℃. Conidia were single-celled, colorless, smooth-walled, fusiform with acute ends, and measured 7.7 to 14.3 × 3.2 to 5.3μm (mean 11.8 ± 1.3 to 4.2 ± 0.5μm, n = 50). Appressoria were single, medium brown, ovate to ellipsoid, 5.8 to 8.5× 3.7 to 6.1μm (mean 7.2 ± 0.7 × 4.9 ± 0.4 μm, n=50). Microscopic examinations showed conidia of the HTK-3 were hyaline, aseptate, and sub-cylindrical, with obtuse apices and tapering bases. Mycelium of which was hyaline, branched and septate. Based on these morphological features, the fungus was tentatively identified as belonging to Colletotrichum acutatum species complex (Damm et al. 2012). For molecular identification, the ITS region, glyceraldehyde-3-phosphate dehydrogenase (GAPDH), chitin synthase (CHS-1), beta-tubulin 2 (TUB2), and actin (ACT) were amplified and sequenced (Liu et al., 2022). The obtained sequences were deposited into the GenBank [accession numbers: OP630818 (ITS); OP649736 (GAPDH); OP649735 (TUB2); OP649738 (CHS-1); OP649737 (ACT)]. For all of these genes, isolates HTK-3 had a 99-100% similarity to multiple C. fioriniae accessions. A maximum likelihood tree was generated from a multiple sequence alignment of reported isolates (Liu et al. 2022) and HTK-3 was identified as C. fioriniae. To fulfill Koch's postulates, ten healthy branches were inoculated with 5-mm-diameter mycelial plugs of each of ten fungal isolates (Wang et al., 2022). PDAs plug without mycelium was used as control. Six days post-inoculation, all branches developed anthracnose symptoms similar to those observed in the field, while the control remained healthy. The pathogenicity tests were repeated twice with the same results. C. fioriniae was re-isolated from the disease branches and the morphology was consistent with original, fulfilling Koch's postulates. The species of C. fioriniae has been reported to cause severe anthracnose of many species of plants (Eaton et al. 2021). To our knowledge, this is the first report of C. fioriniae as a pathogen of R. chinensis in China. The results will help to target the screening of control agents and provide guidance for disease prevention and control.

First report of 'Candidatus Phytoplasma asteris' associated with witches'-broom disease of Pinus yunnanensis in China

Pinus yunnanensis is an evergreen tree belonging to Pinaceae. The species is distributed in the east of Tibet, southwest of Sichuan, southwest of Yunnan, southwest of Guizhou and northwest of Guangxi. It is an indigenous and pioneer tree species for barren mountain afforestation in southwest China. P. yunnanensis has important value to both the building and medicine industries (Liu et al. 2022). In May 2022, P. yunnanensis showing witches'-broom symptom were found in Panzhihua City, Sichuan Province, China. The symptomatic plants had yellow or red needle, and exhibited plexus bud and needle wither. The lateral buds of infected pines developed into twigs. Some lateral buds grew in clusters and a few sprouted needles (Fig.1). The disease was named the P. yunnanensis witches'-broom disease (PYWB) and was found in some areas of Miyi, Renhe, and Dongqu. More than 9% of the pines showed these symptoms in the three areas surveyed, and the disease was spreading. A total of 39 samples were collected from three areas, including 25 symptomatic plants and 14 asymptomatic plants, respectively. The lateral stem tissues of 18 samples were observed under a scanning electron microscope (Hitachi S-3000N). Spherical bodies were found in the phloem sieve cells of symptomatic pines (Fig.1). Total DNA was extracted from 18 plant samples using the CTAB method (Porebski et al. 1997) and subjected to nested-PCR testing. Double-distilled water and DNA extracted from asymptomatic plants were used as negative controls, and DNA extracted from Dodonaea viscosa affected by the D. viscosa witches'-broom disease was used as positive control. Nested PCR was employed to amplify the pathogen's 16S rRNA gene (Lee et al. 1993; Schneider et al. 1993) and 1.2 kb segment were produced (GenBank accessions OP646619; OP646620; OP646621). PCR specific to the ribosomal protein (rp) gene yielded segment of approximately 1.2 kb (Lee et al. 2003)(GenBank accessions OP649589; OP649590; OP649591). The fragment size from 15 samples was consistent with the positive control, confirming the association of phytoplasma with the disease. A BLAST analysis of the 16S rRNA sequences of P. yunnanensis witches'-broom phytoplasma showed that it shared 99.12% ~99.76% identity with that of Trema laevigata witches'-broom phytoplasma (GenBank accession MG755412). The rp sequence shared 99.84%~99.92% identity with that of Cinnamomum camphora witches'-broom phytoplasma (GenBank accession OP649594). An analysis with iPhyClassifier (Zhao et. 2013) showed that the virtual RFLP pattern derived from OP646621 16S rDNA fragment of PYWB phytoplasma is identical (similarity coefficient 1.00) to the reference pattern of 16Sr group I, subgroup B (OY-M, GenBank accession AP006628). The phytoplasma is identified as a 'Candidatus Phytoplasma asteris'-related strain belonging to sub-group 16SrI-B. Interestingly, compared to AP006628, the virtual RFLP pattern derived from OP646619 and OP646620 fragments exhibit differences in three and one cleavage site, with a similarity coefficient of 0.92 and 0.97, respectively (Fig.2). These strains may represent a new subgroup within the 16Sr group I. The phylogenetic tree was reconstructed based on 16S rRNA and rp gene sequences using MEGA versio6.0 (Tamura et al. 2013). The analysis was conducted using the neighbor-joining (NJ) method with 1,000 replicates of bootstrap analysis. The results indicated that the PYWB phytoplasmas grouped into clades including phytoplasmas belonging to 16SrI-B and rpI-B, respectively (Fig.3). In addition, 2-year-old P. yunnanensis were used for grafting assays in nursery, and the twigs from infected pine under natural conditions were used as a scion, and the phytoplasma were detected using nested PCR after grafting for 40 d (Fig.4). In 2008-2014, P. sylvestris and P. mugo in Lituania had excessive branching symptoms that were attributed to 'Ca. Phtyoplasma Pini' (16SrXXI-A) or asteris' (16SrI-A) strains (Valiunas et al. 2015). In 2015, P. pungens with abnormal shoot branching in Maryland were found to be infected by 'Ca. Phytoplasma pini' strain (16SrXXI-B) (Costanzo et al. 2016). To the best of our knowledge, P. yunnanensis is a new host of 'Ca. Phytoplasma asteris'-related strain (16SrI-B) in China. The newly emerged disease is a threat to pines.

Detection of Zika Virus in Aedes aegypti and Aedes albopictus Mosquitoes Collected in Urban Forest Fragments in the Brazilian Amazon

Zika virus (ZIKV) is an RNA flavivirus (Flaviviridae family) endemic in tropical and subtropical regions that is transmitted to humans by Aedes (Stegomyia) species mosquitoes. The two main urban vectors of ZIKV are Aedes aegypti and Aedes albopictus, which can be found throughout Brazil. This study investigated ZIKV infection in mosquito species sampled from urban forest fragments in Manaus (Brazilian Amazon). A total of 905 non-engorged female Ae. aegypti (22 specimens) and Ae. albopictus (883 specimens) were collected using BG-Sentinel traps, entomological hand nets, and Prokopack aspirators during the rainy and dry seasons between 2018 and 2021. All pools were macerated and used to inoculate C6/36 culture cells. Overall, 3/20 (15%) Ae. aegypti and 5/241 (2%) Ae. albopictus pools screened using RT-qPCR were positive for ZIKV. No supernatants from Ae. aegypti were positive for ZIKV (0%), and 15 out of 241 (6.2%) Ae. albopictus pools were positive. In this study, we provide the first-ever evidence of Ae. albopictus naturally infected with ZIKV in the Amazon region.

Effectiveness of forest density reduction treatments for increasing drought resistance of ponderosa pine growth

As the climate changes, it is increasingly important to understand how forests will respond to drought and how forest management can influence those outcomes. In many forests that have become unnaturally dense, "restoration treatments," which decrease stand density using fire and/or mechanical thinning, are generally associated with reduced mortality during drought. However, the effects of such treatments on tree growth during drought are less clear. Previous studies have yielded apparently contradictory results, which may stem from differences in underlying aridity or drought intensity across studies. To address this uncertainty, we studied the growth of ponderosa pine (Pinus ponderosa) in paired treated and untreated areas before and during the extreme California drought of 2012-2016. Our study spanned gradients in climate and tree size and found that density reduction treatments could completely ameliorate drought-driven declines in growth under some contexts, specifically in more mesic areas and in medium-sized trees (i.e., normal annual precipitation > ca. 1100 mm and tree diameter at breast height < ca. 65 cm). Treatments were much less effective in ameliorating drought-associated growth declines in the most water-limited sites and largest trees, consistent with underlying ecophysiology. In medium-sized trees and wetter sites, growth of trees in untreated stands decreased by more than 15% during drought, while treatment-associated increases in growth of 25% or more persisted during the drought. Trees that ultimately died due to drought showed greater growth reductions during drought relative to trees that survived. Our results suggest that density reduction treatments can increase tree resistance to water stress, and they highlight an important pathway for treatments to influence carbon sequestration and other ecosystem services beyond mitigating tree mortality.

Contrasting plant-soil-microbial feedbacks stabilize vegetation types and uncouple topsoil C and N stocks across a subarctic-alpine landscape

Global vegetation regimes vary in belowground carbon (C) and nitrogen (N) dynamics. However, disentangling large-scale climatic controls from the effects of intrinsic plant-soil-microbial feedbacks on belowground processes is challenging. In local gradients with similar pedo-climatic conditions, effects of plant-microbial feedbacks may be isolated from large-scale drivers. Across a subarctic-alpine mosaic of historic grazing fields and surrounding heath and birch forest, we evaluated whether vegetation-specific plant-microbial feedbacks involved contrasting N cycling characteristics and C and N stocks in the organic topsoil. We sequenced soil fungi, quantified functional genes within the inorganic N cycle, and measured ¹⁵ N natural abundance. In grassland soils, large N stocks and low C : N ratios associated with fungal saprotrophs, archaeal ammonia oxidizers, and bacteria capable of respiratory ammonification, indicating maintained inorganic N cycling a century after abandoned reindeer grazing. Toward forest and heath, increasing abundance of mycorrhizal fungi co-occurred with transition to organic N cycling. However, ectomycorrhizal fungal decomposers correlated with small soil N and C stocks in forest, while root-associated ascomycetes associated with small N but large C stocks in heath, uncoupling C and N storage across vegetation types. We propose that contrasting, positive plant-microbial feedbacks stabilize vegetation trajectories, resulting in diverging soil C : N ratios at the landscape scale.

Propagating Visions of a Forest Reservoir: A Supposed Zoonotic Outbreak in the Brong-Ahafo Region of Ghana

When examined closely, the backgrounds of some of the most widely cited origin stories for zoonotic disease outbreaks have been found to be irreconcilable with empirical data. Stated simply, these explanatory landscapes do not appear to have existed. Here, I present a detailed case study of one such fictional landscape, that of a monkey-filled forest which was identified as the source of a suspected zoonotic outbreak in the Brong-Ahafo Region of Ghana in 2010. Taking my approach from cultural epidemiology, I elucidate the mechanisms by which this fictional landscape was constructed and transmitted among the professionals involved in the response.

An Overview of Phytophthora Species on Woody Plants in Sweden and Other Nordic Countries

The genus Phytophthora, with 326 species in 12 phylogenetic clades currently known, includes many economically important pathogens of woody plants. Different Phytophthora species often possess a hemibiotrophic or necrotrophic lifestyle, have either a broad or narrow host range, can cause a variety of disease symptoms (root rot, damping-off, bleeding stem cankers, or blight of foliage), and occur in different growing environments (nurseries, urban and agricultural areas, or forests). Here, we summarize the available knowledge on the occurrence, host range, symptoms of damage, and aggressiveness of different Phytophthora species associated with woody plants in Nordic countries with a special emphasis on Sweden. We evaluate the potential risks of Phytophthora species to different woody plants in this geographical area and emphasize the increasing threats associated with continued introduction of invasive Phytophthora species.

An Assessment of Relations between Vegetation Green FPAR and Vegetation Indices through a Radiative Transfer Model

The fraction of absorbed photosynthetically active radiation (FPAR) is widely used in remote sensing-based production models to estimate gross or net primary production. The forest canopy is composed primarily of photosynthetically active vegetation (PAV, green leaves) and non-photosynthetic vegetation (NPV e.g., branches), which absorb PAR but only the PAR absorbed by PAV is used for photosynthesis. Green FPAR (the fraction of PAR absorbed by PAV) is essential for the accurate estimation of GPP. In this study, the scattering by arbitrary inclined leaves (SAIL) model was reconfigured to partition the PAR absorbed by forest canopies. The characteristics of green FPAR and its relationships with spectral vegetation indices (NDVI, EVI, EVI2, and SAVI) were analyzed. The results showed that green FPAR varied with the canopy structure. In the forests with high coverage, the green FPAR was close to the total FPAR, while in the open forests, the green FPAR was far smaller than the total FPAR. Plant area index had more important impacts on the green FPAR than the proportion of PAV and optical properties of PAV. The significant relationships were found between spectral vegetation indices and the green FPAR, but EVI was more suitable to describe the variation of canopy green FPAR.

Re-examining the evidence for the mother tree hypothesis - resource sharing among trees via ectomycorrhizal networks

Seminal scientific papers positing that mycorrhizal fungal networks can distribute carbon (C) among plants have stimulated a popular narrative that overstory trees, or 'mother trees', support the growth of seedlings in this way. This narrative has far-reaching implications for our understanding of forest ecology and has been controversial in the scientific community. We review the current understanding of ectomycorrhizal C metabolism and observations on forest regeneration that make the mother tree narrative debatable. We then re-examine data and conclusions from publications that underlie the mother tree hypothesis. Isotopic labeling methods are uniquely suited for studying element fluxes through ecosystems, but the complexity of mycorrhizal symbiosis, low detection limits, and small carbon discrimination in biological processes can cause researchers to make important inferences based on miniscule shifts in isotopic abundance, which can be misleading. We conclude that evidence of a significant net C transfer via common mycorrhizal networks that benefits the recipients is still lacking. Furthermore, a role for fungi as a C pipeline between trees is difficult to reconcile with any adaptive advantages for the fungi. Finally, the hypothesis is neither supported by boreal forest regeneration patterns nor consistent with the understanding of physiological mechanisms controlling mycorrhizal symbiosis.

The role of ecosystem transpiration in creating alternate moisture regimes by influencing atmospheric moisture convergence

The terrestrial water cycle links the soil and atmosphere moisture reservoirs through four fluxes: precipitation, evaporation, runoff, and atmospheric moisture convergence (net import of water vapor to balance runoff). Each of these processes is essential for sustaining human and ecosystem well-being. Predicting how the water cycle responds to changes in vegetation cover remains a challenge. Recently, changes in plant transpiration across the Amazon basin were shown to be associated disproportionately with changes in rainfall, suggesting that even small declines in transpiration (e.g., from deforestation) would lead to much larger declines in rainfall. Here, constraining these findings by the law of mass conservation, we show that in a sufficiently wet atmosphere, forest transpiration can control atmospheric moisture convergence such that increased transpiration enhances atmospheric moisture import and results in water yield. Conversely, in a sufficiently dry atmosphere increased transpiration reduces atmospheric moisture convergence and water yield. This previously unrecognized dichotomy can explain the otherwise mixed observations of how water yield responds to re-greening, as we illustrate with examples from China's Loess Plateau. Our analysis indicates that any additional precipitation recycling due to additional vegetation increases precipitation but decreases local water yield and steady-state runoff. Therefore, in the drier regions/periods and early stages of ecological restoration, the role of vegetation can be confined to precipitation recycling, while once a wetter stage is achieved, additional vegetation enhances atmospheric moisture convergence and water yield. Recent analyses indicate that the latter regime dominates the global response of the terrestrial water cycle to re-greening. Evaluating the transition between regimes, and recognizing the potential of vegetation for enhancing moisture convergence, are crucial for characterizing the consequences of deforestation as well as for motivating and guiding ecological restoration.

Habitat use, survival, and migration of a little-known East Asian endemic, the yellow-throated bunting Emberiza elegans

Basic information on the ecology of species is key for their conservation. Here we study the ecology of the little-known yellow-throated bunting Emberiza elegans based on a multi-year study on its breeding grounds in the Russian Far East. For the first time in this species, we quantified breeding habitat parameters, calculated sex-specific apparent survival, and determined individual nonbreeding locations using light-level geolocation. We found that the habitat around song posts of male yellow-throated buntings is characterized by tree and shrub layers on richly littered moist ground. Habitat use overlaps with co-occurring Tristram's Buntings Emberiza tristrami and Black-faced Buntings E. spodocephala, but territories differ especially in tree cover and litter cover. Based on 4 years of color-ringing data of 72 individuals, we calculated an apparent survival rate of 36%, with higher survival estimates for male than for female yellow-throated buntings. We found no effect of carrying a geolocator on survival. We retrieved six geolocators from males. All birds migrated south-westward during autumn and spent the nonbreeding season at locations in China 700-1700 km away from their breeding sites. At least two individuals spent the boreal winter outside of the known range in northern or central China. Birds left the breeding area between early October and early November and returned between mid-March and mid-April. Our data on habitat use, survival rate, and migratory connectivity will help to assess threats to the populations of this enigmatic species, which might include habitat loss due to forest fires on the breeding grounds, and unsustainable harvest for consumption during the nonbreeding season.

Effect of environmental and spatial factors on the phylogenetic and functional diversity of the Mediterranean tree communities of Europe

The tree flora of the Mediterranean Basin contains an outstanding taxonomic richness and a high proportion of endemic taxa. Contrary to other regions of the Mediterranean biome, a comprehensive phylogenetic analysis of the relationship between phylogenetic diversity, trait diversity and environmental factors in a spatial ecological context is lacking. We inferred the first calibrated phylogeny of 203 native tree species occurring in the European Mediterranean Basin based on 12 DNA regions. Using a set of four functional traits, we computed phylogenetic diversity for all 10,042 grid cells of 10 × 10 km spatial resolution to completely cover Mediterranean Europe. Then, we tested the spatial influence of environmental factors on tree diversity. Our results suggest that the nature of the relationship between traits and phylogeny varies among the different studied traits and according to the evolutionary distance considered. Phylogenetic diversity and functional diversity of European Mediterranean trees correlated strongly with species richness. High values of these diversity indices were located in the north of the study area, at high altitude, and minimum temperature of the coldest month. In contrast, the two phylogenetic indices that were not correlated with species richness (Mean Phylogenetic Distance, Phylogenetic Species Variability) were located in the south of the study area and were positively correlated with high altitude, soil organic carbon stock and sand soil texture. Our study provides support for the use of phylogenies in conservation biology to assess ecosystem functioning, and provides insights for the implementation of sustainable forest ecosystem management.

Spatial heterogeneity of soil available medium- and micro-elements in evergreen-deciduous broadleaved forest in karst

Understanding the spatial heterogeneity of soil available medium- and micro-elements in karst area can provide a valuable theoretical guideline for soil nutrient management of karst ecosystem. We collected soil samples at a soil depth of 0-10 cm using grid sampling (20 m×20 m) in a 25 hm² (500 m×500 m) dynamic monitoring plot. We further analyzed the spatial variability of soil medium- and micro-elements and their drivers, with classic statistics analysis and geo-statistics analysis. The results showed that the average contents of exchangeable Ca and Mg and available Fe, Mn, Cu, Zn, and B were 7870, 1490, 30.24, 149.12, 1.77, 13.54, and 0.65 mg·kg^-1, respectively. The coefficient of variation of the nutrients ranged from 34.5% to 68.8%, showing a medium degree of their spatial variation. The coefficient of determination of the best-fit semi-variogram models of each nutrient was higher than 0.90, except for available Zn (0.78), indicating a strong predictive power for the spatial variation of the nutrients. The nugget coefficients for all the nutrients were less than 50%, showing a moderate spatial correlation, and the structural factors played a pivotal role. The spatially autocorrelated variation was within the range of 60.3-485.1 m, among which available Zn showed the lowest range and the deepest fragmentation degree. The spatial distribution of exchangeable Ca, Mg, and available B were consistent, with contents in the depression being significantly lower than that in other habitats. The contents of available Fe, Mn, and Cu declined with the increases of altitude and were significantly lower on the hilltop than in other habitats. The spatial variation of soil medium- and micro-elements was closely related to topographic factors in karst forest. Elevation, slope, soil thickness, and rock exposure rate were the primary drivers of spatial variation of soil elements and need to be considered in soil nutrient management of karst forestlands.

Decrease in Soil Functionalities and Herbs' Diversity, but Not That of Arbuscular Mycorrhizal Fungi, Linked to Short Fire Interval in Semi-Arid Oak Forest Ecosystem, West Iran

The semi-arid forest ecosystems of western Iran dominated by Quercus brantii are often disturbed by wildfires. Here, we assessed the effects of short fire intervals on the soil properties and community diversity of herbaceous plants and arbuscular mycorrhizal fungi (AMF), as well as the interactions between these ecosystem features. Plots burned once or twice within 10 years were compared to unburned plots over a long time period (control sites). Soil physical properties were not affected by the short fire interval, except bulk density, which increased. Soil geochemical and biological properties were affected by the fires. Soil organic matter and nitrogen concentrations were depleted by two fires. Short intervals impaired microbial respiration, microbial biomass carbon, substrate-induced respiration, and urease enzyme activity. The successive fires affected the AMF's Shannon diversity. The diversity of the herb community increased after one fire and dropped after two, indicating that the whole community structure was altered. Two fires had greater direct than indirect effects on plant and fungal diversity, as well as soil properties. Short-interval fires depleted soil functional properties and reduced herb diversity. With short-interval fires probably fostered by anthropogenic climate change, the functionalities of this semi-arid oak forest could collapse, necessitating fire mitigation.

Was it really different? COVID-19-pandemic period in long-term recreation monitoring – A case study from Polish forests

The COVID -19 pandemic posed serious challenge for securing public health worldwide. Public health preparedness and restrictions put in place impacted many aspects of human life, including recreational activities and access to outdoor recreational destinations. Green spaces have become one of the few sources of resilience during the coronavirus crisis due to their restorative effects on psychophysical health and community well-being. The aim of this study is to analyse the impact of the COVID -19 pandemic on forest visitation. The results are based upon long-term visitor data acquired via pyroelectric sensors (Eco-Counter) in three forest districts located in Poland (Browsk, Gdansk & Kozienice Forest Districts). The analysis covers the period between January 01, 2019 and December 31, 2020 and the results confirm changes in recreational use in the studied forest areas during the pandemic compared to the preceding year. However, observed changes in forest visitation vary by pandemic period and study area. The ban on access to forest areas significantly reduced the number of forest visits in all studied areas. The number of visits to sub-urban forests (Gdansk Forest District) and to remote nature-based tourist destinations (Browsk Forest District) increased in the later pandemic periods, especially in the summer months of 2020, while it remained the same in a popular nearby recreation area: Kozienice Forest District. There were only minor temporal shifts in the distribution of weekly and daily visits. The results are important for public health preparedness planning in crisis situations and for provisioning conditions supporting societal health and well-being. Objective data on forest visits are necessary for successful management of forest areas and surrounding amenities. More cross-sector collaboration and public participation would be desirable to create sustainable, resilient, and liveable spaces for the society.

Management Implications

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Long-term visitation monitoring is crucial for successful management of outdoor recreation destinations and their catchment areas.

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Objective numbers concerning forest visitation from the pre-pandemic and COVID-19 pandemic period allow observing trends and making fact-based management decisions during period of crisis.

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Changes in the investigated three forest study areas in Poland were not homogenous, which implies the necessity of systematic visitor monitoring in multiple destinations, in order to cover different types of forest areas and also local diversity in recreational use.

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More intersectoral, interdisciplinary and transdisciplinary exchange would be desirable to better integrate existing on-site visitor monitoring data into decision making processes related to forest management, urban planning, transportation, tourism and public health.

Advancing research on ectomycorrhizal fungal adaptation with landscape genomics

Ectomycorrhizal (ECM) fungi serve key functions in forest ecosystems by supplying water and nutrients to tree hosts, yet mutualistic plant-fungi interactions are jeopardised by environmental alterations. Here, we discuss the great potential and current limitations of landscape genomics in investigating signatures of local adaptation in natural populations of ECM fungi.