Balancing the books of nature by accounting for ecosystem condition following ecological restoration

Demand for ecological restoration of Earth's degraded ecosystems has increased significantly since the adoption of The Kunming-Montreal Global Biodiversity Framework in December 2022, with target 2 aiming to ensure that at least 30% of degraded ecosystems are under effective restoration by 2030. More recently, in December 2023, the Australian Parliament introduced the Nature Repair Act, which establishes a framework for the world's first legislated, national, voluntary biodiversity market. How can the effectiveness of these ambitious targets be measured? Natural Capital Accounting (NCA) provides a framework to measure changes in ecosystem condition that is applicable across ecosystems and potentially catalogue effects of restoration interventions to drive investment, improvement to practice, and ultimately, to better protect the Earth's ecosystems. However, the framework has not been tested in this context. In this progressive approach, we populated the leading global NCA framework with ecological data to quantify changes in ecosystem condition after restoration. In principle, NCA is fit for purpose, however, methodological refinements and ecological expertise are needed to unlock its full potential. These tweaks will facilitate adoption and standardisation of reporting as efforts ramp up to meet ambitious global restoration targets.

Effects of plant diversity on productivity strengthen over time due to trait-dependent shifts in species overyielding

Plant diversity effects on community productivity often increase over time. Whether the strengthening of diversity effects is caused by temporal shifts in species-level overyielding (i.e., higher species-level productivity in diverse communities compared with monocultures) remains unclear. Here, using data from 65 grassland and forest biodiversity experiments, we show that the temporal strength of diversity effects at the community scale is underpinned by temporal changes in the species that yield. These temporal trends of species-level overyielding are shaped by plant ecological strategies, which can be quantitatively delimited by functional traits. In grasslands, the temporal strengthening of biodiversity effects on community productivity was associated with increasing biomass overyielding of resource-conservative species increasing over time, and with overyielding of species characterized by fast resource acquisition either decreasing or increasing. In forests, temporal trends in species overyielding differ when considering above- versus belowground resource acquisition strategies. Overyielding in stem growth decreased for species with high light capture capacity but increased for those with high soil resource acquisition capacity. Our results imply that a diversity of species with different, and potentially complementary, ecological strategies is beneficial for maintaining community productivity over time in both grassland and forest ecosystems.

Extreme drought impacts have been underestimated in grasslands and shrublands globally

Climate change is increasing the frequency and severity of short-term (~1 y) drought events-the most common duration of drought-globally. Yet the impact of this intensification of drought on ecosystem functioning remains poorly resolved. This is due in part to the widely disparate approaches ecologists have employed to study drought, variation in the severity and duration of drought studied, and differences among ecosystems in vegetation, edaphic and climatic attributes that can mediate drought impacts. To overcome these problems and better identify the factors that modulate drought responses, we used a coordinated distributed experiment to quantify the impact of short-term drought on grassland and shrubland ecosystems. With a standardized approach, we imposed ~a single year of drought at 100 sites on six continents. Here we show that loss of a foundational ecosystem function-aboveground net primary production (ANPP)-was 60% greater at sites that experienced statistically extreme drought (1-in-100-y event) vs. those sites where drought was nominal (historically more common) in magnitude (35% vs. 21%, respectively). This reduction in a key carbon cycle process with a single year of extreme drought greatly exceeds previously reported losses for grasslands and shrublands. Our global experiment also revealed high variability in drought response but that relative reductions in ANPP were greater in drier ecosystems and those with fewer plant species. Overall, our results demonstrate with unprecedented rigor that the global impacts of projected increases in drought severity have been significantly underestimated and that drier and less diverse sites are likely to be most vulnerable to extreme drought.

Niche differentiation of Mucoromycotinian and Glomeromycotinian arbuscular mycorrhizal fungi along a 2-million-year soil chronosequence

Current literature suggests ecological niche differentiation between co-occurring Mucoromycotinian arbuscular mycorrhizal fungi (M-AMF) and Glomeromycotinian AMF (G-AMF), but experimental evidence is limited. We investigated the influence of soil age, water availability (wet and dry), and plant species (native Microlaena stipoides and exotic Trifolium subterraneum) on anatomical root colonisation and DNA profiles of M-AMF and G-AMF under glasshouse conditions. We grew seedlings of each species in soils collected from the four stages of a soil chronosequence, where pH decreases from the youngest to oldest stages, and phosphorus (P) is low in the youngest and oldest, but high in the intermediate stages. We scored the percentage of root length colonised and used DNA metabarcoding to profile fungal richness and community composition associated with treatment combinations. Soil age, water availability, and plant species were important influencers of root colonisation, although no M-AMF were visible following staining of M. stipoides roots. Soil age and host plant influenced fungal richness and community composition. However, response to soil age, potential host species, and water availability differed between M-AMF and G-AMF. Root colonisation of T. subterraneum by M-AMF and G-AMF was inversely correlated with soil P level. Community composition of M-AMF and G-AMF was structured by soil age and, to a lesser extent, plant species. Richness of M-AMF and G-AMF was negatively, and positively, correlated with available P, respectively. These findings are experimental evidence of ecological niche differentiation of M-AMF and G-AMF and invite further exploration into interactive effects of abiotic and biotic factors on their communities along successional trajectories.

Abiotic and biotic responses to woody debris additions in restored old fields in a multi-site Before-After-Control-Impact experiment

Ecological restoration of former agricultural land can improve soil conditions, recover native vegetation, and provide fauna habitat. However, restoration benefits are often associated with time lags, as many attributes, such as leaf litter and coarse woody debris, need time to accumulate. Here, we experimentally tested whether adding mulch and logs to restoration sites in semi-arid Western Australia can accelerate restoration benefits. All sites had been cropped and then planted with native trees and shrubs (i.e., Eucalyptus, Melaleuca, and Acacia spp.) 10 years prior to our experiment, to re-establish the original temperate eucalypt woodland vegetation community. We used a Multi-site Before-After-Control-Impact (MBACI) design to test the effects on 30 abiotic and biotic response variables over a period of 2 years. Of the 30 response variables, a significant effect was found for just four variables: volumetric water content, decomposition, native herbaceous species cover and species richness of disturbance specialist ants. Mulch addition had a positive effect on soil moisture when compared to controls but suppressed growth of native (but not exotic) herbaceous plants. On plots with log additions, decomposition rates decreased, and species richness of disturbance specialist ants increased. However, we found no effect on total species richness and abundance of other ant species groups. The benefit of mulch to soil moisture was offset by its disbenefit to native herbs in our study. Given time, logs may also provide habitat for ant species that prefer concealed habitats. Indeed, benefits to other soil biophysical properties, vegetation, and ant fauna may require longer time frames to be detected. Further research is needed to determine whether the type, quantity, and context of mulch and log additions may improve their utility for old field restoration and whether effects on native herbs are correlated with idiosyncratic climatic conditions.

P is for persistence: Soil phosphorus remains elevated for more than a decade after old field restoration

Understanding constraints to ecological restoration on former agricultural land has become increasingly important due to agricultural land degradation in the developed world, and growing evidence for enduring agricultural legacies that limit native species recovery. In particular, the removal of native plant biomass and subsequent disturbance of soil properties through farming activities can alter soil ecosystem processes. Planting of native plant species is a common approach to restoring native vegetation on agricultural land and is assumed to benefit soil ecosystem processes, but the degree to which altered soil chemical processes recover is poorly documented. We investigated recovery of soil chemical properties after restoration in semiarid Western Australia, hypothesizing that elevated nutrient concentrations would gradually decline post planting, but available phosphorus (P) concentrations would remain higher than reference conditions. We used a space-for-time substitution approach, comparing 10 planted old field plots with matched fallow cropland and reference woodlands. Sampling on planted old fields and reference woodland plots was stratified into open patches and under tree canopy to account for consistent differences between these areas. The most prominent legacy of cropping was significantly and substantially higher concentrations of soil available P in fallow croplands and restored old fields compared with reference woodlands. Soil mineral nitrogen (N) concentrations were elevated in fallow croplands compared to open patches in reference woodlands (ammonium and nitrate) and under the tree canopy (ammonium). However, in restored old fields, mineral N concentrations were similar to woodland sites, providing evidence for amelioration over time. No significant differences in nutrient concentrations under tree canopies compared with open patches had developed in the planted old fields, despite a distinction between open patches and he under ttree canopy in reference woodlands for total N. We conclude that soil P legacies in old fields may inhibit the recolonization of native species that are sensitive to, or uncompetitive at, elevated P concentrations. To achieve full recovery, further research is required to test restoration practices aimed at reducing soil P concentrations to facilitate native plant establishment and persistence.

Agricultural land-use favours Mucoromycotinian, but not Glomeromycotinian, arbuscular mycorrhizal fungi across ten biomes

Globally, agricultural land-use negatively affects soil biota that contribute to ecosystem functions such as nutrient cycling, yet arbuscular mycorrhizal fungi (AMF) are promoted as essential components of agroecosystems. Arbuscular mycorrhizal fungi include Glomeromycotinian AMF (G-AMF) and the arbuscule-producing fine root endophytes, recently re-classified into the Endogonales order within Mucoromycotina. The correct classification of Mucoromycotinian AMF (M-AMF) and the availability of new molecular tools can guide research to better the understanding of their diversity and ecology. To investigate the impact on G-AMF and M-AMF of agricultural land-use at a continental scale, we sampled DNA from paired farm and native sites across 10 Australian biomes. Glomeromycotinian AMF were present in both native and farm sites in all biomes. Putative M-AMF were favoured by farm sites, rare or absent in native sites, and almost entirely absent in tropical biomes. Temperature, rainfall, and soil pH were strong drivers of richness and community composition of both groups, and plant richness was an important mediator. Both fungal groups occupy different, but overlapping, ecological niches, with M-AMF thriving in temperate agricultural landscapes. Our findings invite exploration of the origin and spread of M-AMF and continued efforts to resolve the phylogeny of this newly reclassified group of AMF.

AusTraits, a curated plant trait database for the Australian flora

We introduce the AusTraits database - a compilation of values of plant traits for taxa in the Australian flora (hereafter AusTraits). AusTraits synthesises data on 448 traits across 28,640 taxa from field campaigns, published literature, taxonomic monographs, and individual taxon descriptions. Traits vary in scope from physiological measures of performance (e.g. photosynthetic gas exchange, water-use efficiency) to morphological attributes (e.g. leaf area, seed mass, plant height) which link to aspects of ecological variation. AusTraits contains curated and harmonised individual- and species-level measurements coupled to, where available, contextual information on site properties and experimental conditions. This article provides information on version 3.0.2 of AusTraits which contains data for 997,808 trait-by-taxon combinations. We envision AusTraits as an ongoing collaborative initiative for easily archiving and sharing trait data, which also provides a template for other national or regional initiatives globally to fill persistent gaps in trait knowledge.

Negative effects of nitrogen override positive effects of phosphorus on grassland legumes worldwide

Anthropogenic nutrient enrichment is driving global biodiversity decline and modifying ecosystem functions. Theory suggests that plant functional types that fix atmospheric nitrogen have a competitive advantage in nitrogen-poor soils, but lose this advantage with increasing nitrogen supply. By contrast, the addition of phosphorus, potassium, and other nutrients may benefit such species in low-nutrient environments by enhancing their nitrogen-fixing capacity. We present a global-scale experiment confirming these predictions for nitrogen-fixing legumes (Fabaceae) across 45 grasslands on six continents. Nitrogen addition reduced legume cover, richness, and biomass, particularly in nitrogen-poor soils, while cover of non-nitrogen-fixing plants increased. The addition of phosphorous, potassium, and other nutrients enhanced legume abundance, but did not mitigate the negative effects of nitrogen addition. Increasing nitrogen supply thus has the potential to decrease the diversity and abundance of grassland legumes worldwide regardless of the availability of other nutrients, with consequences for biodiversity, food webs, ecosystem resilience, and genetic improvement of protein-rich agricultural plant species.

Evidence for Niche Differentiation in the Environmental Responses of Co-occurring Mucoromycotinian Fine Root Endophytes and Glomeromycotinian Arbuscular Mycorrhizal Fungi

Fine root endophytes (FRE) were traditionally considered a morphotype of arbuscular mycorrhizal fungi (AMF), but recent genetic studies demonstrate that FRE belong within the subphylum Mucoromycotina, rather than in the subphylum Glomeromycotina with the AMF. These findings prompt enquiry into the fundamental ecology of FRE and AMF. We sampled FRE and AMF in roots of Trifolium subterraneum from 58 sites across temperate southern Australia. We investigated the environmental drivers of composition, richness, and root colonization of FRE and AMF by using structural equation modelling and canonical correspondence analyses. Root colonization by FRE increased with increasing temperature and rainfall but decreased with increasing phosphorus (P). Root colonization by AMF increased with increasing soil organic carbon but decreased with increasing P. Richness of FRE decreased with increasing temperature and soil pH. Richness of AMF increased with increasing temperature and rainfall but decreased with increasing soil aluminium (Al) and pH. Aluminium, soil pH, and rainfall were, in decreasing order, the strongest drivers of community composition of FRE; they were also important drivers of community composition of AMF, along with temperature, in decreasing order: rainfall, Al, temperature, and soil pH. Thus, FRE and AMF showed the same responses to some (e.g. soil P, soil pH) and different responses to other (e.g. temperature) key environmental factors. Overall, our data are evidence for niche differentiation among these co-occurring mycorrhizal associates.

Field-Deployed Extruded Seed Pellets Show Promise for Perennial Grass Establishment in Arid Zone Mine Rehabilitation

Current methods of mine rehabilitation in the arid zone have a high failure rate at seedling emergence largely due to limited availability of topsoil and low water-holding capacity of alternative growth substrates such as mining overburden and tailings. Further, seedlings have consistently failed to emerge from seeds sown on the soil surface using traditional broadcasting methods. Seed pellets, formed by extruding soil mixtures and seeds into pellets, can potentially increase soil water uptake through enhanced soil-seed contact and thereby improve seedling emergence. We tested an extruded seed pelleting method in a three-factor field experiment (i.e., different pellet-soil mixtures, organic amendments, and simulated rainfall regimes) in north-western Australia. Given the observed lack of seedling emergence from broadcast seeds, the aims of the experiment were to assess: (i) the use of pellets to promote native seedling emergence and establishment and; (ii) the soil physico-chemical and microbiological changes that occur with this method of rehabilitation. The effects of pellet-soil mixtures, organic amendment, and rainfall regime on seedling emergence and survival of three native plant species suggest trade-offs among responses. Pellets made with a 1:1 blend of topsoil and a loamy-sand waste material had the highest seedling emergence, while 100% topsoil pellets had lower emergence probably because of hardsetting. Triodia pungens (a native grass) survived to the end of the experiment while Indigofera monophylla and Acacia inaequilatera (native shrubs) emerged but did not survive. Adding an organic amendment in the extruded pellet inhibited Triodia seedling emergence but increased soil microbial activity. Overall, extruded pellets made from a 1:1 blend showed promise for the establishment of Triodia seeds and beneficially, incorporates mine waste overburden and lesser amounts of topsoil. Further research is needed to improve pelleting production and to test the applicability of the method at scale, for different species and other ecosystem types.

First Cryo-Scanning Electron Microscopy Images and X-Ray Microanalyses of Mucoromycotinian Fine Root Endophytes in Vascular Plants

AIMS

Arbuscule-producing fine root endophytes (FRE) (previously incorrectly Glomus tenue) were recently placed within subphylum Mucoromycotina; the first report of arbuscules outside subphylum Glomeromycotina. Here, we aimed to estimate nutrient concentrations in plant and fungal structures of FRE and to test the utility of cryo-scanning electron microscopy (cryoSEM) for studying these fungi.

METHODS

We used replicated cryoSEM and X-ray microanalysis of heavily colonized roots of Trifolium subterraneum.

RESULTS

Intercellular hyphae and hyphae in developed arbuscules were consistently very thin; 1.35 ± 0.03 μm and 0.99 ± 0.03 μm in diameter, respectively (mean ± SE). Several intercellular hyphae were often adjacent to each other forming "hyphal ropes." Developed arbuscules showed higher phosphorus concentrations than senesced arbuscules and non-colonized structures. Senesced arbuscules showed greatly elevated concentrations of calcium and magnesium.

CONCLUSION

While uniformly thin hyphae and hyphal ropes are distinct features of FRE, the morphology of fully developed arbuscules, elevated phosphorus in fungal structures, and accumulation of calcium with loss of structural integrity in senesced arbuscules are similar to glomeromycotinian fungi. Thus, we provide evidence that FRE may respond to similar host-plant signals or that the host plant may employ a similar mechanism of association with FRE and AMF.

Microbial processing of plant remains is co-limited by multiple nutrients in global grasslands

Microbial processing of aggregate-unprotected organic matter inputs is key for soil fertility, long-term ecosystem carbon and nutrient sequestration and sustainable agriculture. We investigated the effects of adding multiple nutrients (nitrogen, phosphorus and potassium plus nine essential macro- and micro-nutrients) on decomposition and biochemical transformation of standard plant materials buried in 21 grasslands from four continents. Addition of multiple nutrients weakly but consistently increased decomposition and biochemical transformation of plant remains during the peak-season, concurrent with changes in microbial exoenzymatic activity. Higher mean annual precipitation and lower mean annual temperature were the main climatic drivers of higher decomposition rates, while biochemical transformation of plant remains was negatively related to temperature of the wettest quarter. Nutrients enhanced decomposition most at cool, high rainfall sites, indicating that in a warmer and drier future fertilized grassland soils will have an even more limited potential for microbial processing of plant remains.

Effect of plant root symbionts on performance of native woody species in competition with an invasive grass in multispecies microcosms

The majority of terrestrial plants form mutualistic associations with arbuscular mycorrhizal fungi (AMF) and rhizobia (i.e., nitrogen-fixing bacteria). Understanding these associations has important implications for ecological theory and for restoration practice. Here, we tested whether the presence of AMF and rhizobia influences the performance of native woody plants invaded by a non-native grass in experimental microcosms. We planted eight plant species (i.e., Acacia acuminata, A. microbotrya, Eucalyptus loxophleba subsp. loxophleba, E. astringens, Calothamnus quadrifidus, Callistemon phoeniceus, Hakea lissocarpha and H. prostrata) in microcosms of field-conditioned soil with and without addition of AMF and rhizobia in a fully factorial experimental design. After seedling establishment, we seeded half the microcosms with an invasive grass Bromus diandrus. We measured shoot and root biomass of native plants and Bromus, and on roots, the percentage colonization by AMF, number of rhizobia-forming nodules and number of proteaceous root clusters. We found no effect of plant root symbionts or Bromus addition on performance of myrtaceous, and as predicted, proteaceous species as they rely little or not at all on AMF and rhizobia. Soil treatments with AMF and rhizobia had a strong positive effect (i.e., larger biomass) on native legumes (A. microbotrya and A. acuminata). However, the beneficial effect of root symbionts on legumes became negative (i.e., lower biomass and less nodules) if Bromus was present, especially for one legume, i.e., A. acuminata, suggesting a disruptive effect of the invader on the mutualism. We also found a stimulating effect of Bromus on root nodule production in A. microbotrya and AMF colonization in A. acuminata which could be indicative of legumes' increased resource acquisition requirement, i.e., for nitrogen and phosphorus, respectively, in response to the Bromus addition. We have demonstrated the importance of measuring belowground effects because the aboveground effects gave limited indication of the effects occurring belowground.

Threats to biodiversity from cumulative human impacts in one of North America's last wildlife frontiers

Land-use change is the largest proximate threat to biodiversity yet remains one of the most complex to manage. In British Columbia (BC), where large mammals roam extensive tracts of intact habitat, continued land-use development is of global concern. Extant mammal diversity in BC is unrivalled in North America owing, in part, to its unique position at the intersection of alpine, boreal, and temperate biomes. Despite high conservation values, understanding of cumulative ecological impacts from human development is limited. Using cumulative-effects-assessment (CEA) methods, we assessed the current human footprint over 16 regional ecosystems and 7 large mammal species. Using historical and current range estimates of the mammals, we investigated impacts of human land use on species' persistence. For ecosystems, we found that bunchgrass, coastal Douglas fir, and ponderosa pine have been subjected to over 50% land-use conversion, and over 85% of their spatial extent has undergone either direct or estimated indirect impacts. Of the mammals we considered, wolves were the least affected by land conversion, yet all species had reduced ranges compared with historical estimates. We found evidence of a hard trade-off between development and conservation, most clearly for mammals with large distributions and ecosystems with high levels of conversion. Rather than serve as a platform to monitor species decline, we strongly advocate these data be used to inform land-use planning and to assess current conservation efforts. More generally, CEAs offer a robust tool to inform wildlife and habitat conservation at scale.

The role of landscape connectivity in resistance, resilience, and recovery of multi-trophic microarthropod communities

There is a need to find generalizable mechanisms supporting ecological resilience, resistance, and recovery. One hypothesized mechanism is landscape connectivity, a habitat configuration that allows movement of biotic and abiotic resources between local patches. Whether connectivity increases all or only one of resistance, resilience, and recovery has not been teased apart, however, and has been difficult to test at large scales and for complex trophic webs. Natural microcosms offer a complex system that can be manipulated to test questions at a landscape-scale relative to the community of study. Here, we test the role of connectivity in altering resistance, resilience, and recovery to a gradient of heating disturbance in moss microcosms. To test across trophic levels, we focused on community composition as our metric of response and applied three connectivity treatments - isolation, connected to an equally disturbed patch, and connected to an undisturbed patch. We found that connectivity between equally disturbed patches boosted resistance of communities to disturbance. Additionally, recovery was linear and rapid in communities connected to undisturbed landscapes, hump shaped when connected to equally disturbed landscapes, and linear but slow in isolated communities. We did not find thresholds on the disturbance gradient at which disturbed communities exhibited zero or increasing dissimilarity to controls through time, so were unable to draw conclusions on the role of connectivity in ecological resilience. Ultimately, isolated communities exhibited increasingly variable composition and slow recovery patterns even in control communities when compared with connected treatments.

Novel ecosystems: Governance and conservation in the age of the Anthropocene

Meeting conservation objectives in an era of global environmental change has precipitated debate about where and how to intervene. Ecological and social values of novel ecosystems are particularly contested. Governance has a role to play, but this role is underexplored. Here, we critically review the novel ecosystems literature to identify challenges that fall within the realm of governance. Using a conceptual framework for analysing adaptive governance, we consider how governance could help address five challenges. Specifically, we argue that reforming governance can support the re-framing of policy objectives for ecosystems where transformation is likely, and in doing so, it could highlight the tensions between the emergence of novel ecosystems on the one hand and cultural expectations about how ecosystems should look on the other. We discuss the influence of power, authority and administrative competence on conservation efforts in times of environmental change. We consider how buffering can address translational mismatch between conventional conservation policy and modern ecological reality. This review provides insights into how governance reform could enable more adaptive responses to transformative changes, such as novel ecosystems, while remaining committed to achieving conservation outcomes. Indeed, at their best, adaptive responses would encompass the reality of ecological transformation while being sympathetic to concerns about undesirable outcomes. Connections between researchers in the fields of governance, ecology and conservation could help to achieve these twin aims. We provide examples of governance and policy-making techniques that can support context-specific governance reform that supports more effective conservation in the Anthropocene.

Movers and Stayers: Novel Assemblages in Changing Environments

Increased attention to species movement in response to environmental change highlights the need to consider changes in species distributions and altered biological assemblages. Such changes are well known from paleoecological studies, but have accelerated with ongoing pervasive human influence. In addition to species that move, some species will stay put, leading to an array of novel interactions. Species show a variety of responses that can allow movement or persistence. Conservation and restoration actions have traditionally focused on maintaining or returning species in particular places, but increasingly also include interventions that facilitate movement. Approaches are required that incorporate the fluidity of biotic assemblages into the goals set and interventions deployed.

Fine root endophytes under scrutiny: a review of the literature on arbuscule-producing fungi recently suggested to belong to the Mucoromycotina

Fine root endophytes (FRE) are arbuscule-forming fungi presently considered as a single species-Glomus tenue in the Glomeromycota (Glomeromycotina)-but probably belong within the Mucoromycotina. Thus, FRE are the only known arbuscule-forming fungi not within the arbuscular mycorrhizal fungi (AMF; Glomeromycotina) as currently understood. Phylogenetic differences between FRE and AMF could reflect ecological differences. To synthesize current ecological knowledge, we reviewed the literature on FRE and identified 108 papers that noted the presence of FRE and, in some, the colonization levels for FRE or AMF (or both). We categorized these records by geographic region, host-plant family and environment (agriculture, moderate-natural, low-temperature, high-altitude and other) and determined their influence on the percentage of root length colonized by FRE in a meta-analysis. We found that FRE are globally distributed, with many observations from Poaceae, perhaps due to grasses being widely distributed. In agricultural environments, colonization by FRE often equalled or exceeded that of AMF, particularly in Australasia. In moderate-natural and high-altitude environments, average colonization by FRE (~10%) was lower than that of AMF (~35%), whereas in low-temperature environments, colonization was similar (~20%). Several studies suggested that FRE can enhance host-plant phosphorus uptake and growth, and may be more resilient than AMF to environmental stress in some host plants. Further research is required on the functioning of FRE in relation to the environment, host plant and co-occurring AMF and, in particular, to examine whether FRE are important for plant growth in stressful environments. Targeted molecular primers are urgently needed for further research on FRE.

Plant functional traits of dominant native and invasive species in mediterranean-climate ecosystems

The idea that dominant invasive plant species outperform neighboring native species through higher rates of carbon assimilation and growth is supported by several analyses of global data sets. However, theory suggests that native and invasive species occurring in low-resource environments will be functionally similar, as environmental factors restrict the range of observed physiological and morphological trait values. We measured resource-use traits in native and invasive plant species across eight diverse vegetation communities distributed throughout the five mediterranean-climate regions, which are drought prone and increasingly threatened by human activities, including the introduction of exotic species. Traits differed strongly across the five regions. In regions with functional differences between native and invasive species groups, invasive species displayed traits consistent with high resource acquisition; however, these patterns were largely attributable to differences in life form. We found that species invading mediterranean-climate regions were more likely to be annual than perennial: three of the five regions were dominated by native woody species and invasive annuals. These results suggest that trait differences between native and invasive species are context dependent and will vary across vegetation communities. Native and invasive species within annual and perennial groups had similar patterns of carbon assimilation and resource use, which contradicts the widespread idea that invasive species optimize resource acquisition rather than resource conservation. .

Q-switched neodymium-doped Y3Al5O12-based silica fiber laser

We present pulsed laser operation in a Nd-doped, Y3Al5O12-based silica fiber. The fiber was fabricated using the rod-in-tube technique with a Nd:YAG crystal rod as the core material and a silica tube for the cladding material. A spectroscopy study revealed that the core region had become amorphous in the process of fiber drawing. Q-switched pulsed laser operation was realized at a wavelength of 1058 nm when the fiber was cladding pumped at a wavelength of 808 nm. The laser delivered 38 μJ of energy in 65 ns pulses. The extracted energy was limited due to the multimodal operation of the fiber. Laser slope efficiency in continuous wave operation reached 52%. The spectroscopic properties of the fabricated fiber are discussed and compared to a Nd:YAG crystal and a Nd:Al-doped silica fiber.

Synchronous polyandry and multiple paternity in the frog Crinia georgiana (Anura: Myobatrachidae)

Multiple paternity has rarely been reported in anuran amphibians, with only three previous documented examples. For the Australian frog Crinia georgiana, we observed synchronous polyandry in an average of 44% of matings observed at four field sites. This suggests matings involving more than one male are common in this species. One to eight males were observed in amplectant groups with second males amplexed ventrally. Genetic analyses, using allozyme electrophoresis, of offspring from two matings indicated that at least two of three possible males fathered offspring. Third males were unlikely to have shared paternity, explained by their inappropriate position during amplexus. Multiple paternity may be more common in frogs than has been reported. Copyright 1999 The Association for the Study of Animal Behaviour.