Dalbergia odorifera undergoes massive molecular shifts in response to waterlogging combined with salinity

Field and greenhouse studies attempting to describe the molecular responses of plant species under waterlogging (WL) combined with salinity (ST) are almost nonexistent. We integrated transcriptional, metabolic, and physiological responses involving several crucial transcripts and common differentially expressed genes and metabolites in fragrant rosewood (Dalbergia odorifera) leaflets to dissect plant-specific molecular responses and patterns under WL combined with ST (SWL). We discovered that the synergistic pattern of the transcriptional response of fragrant rosewood under SWL was exclusively characterized by the number of regulated transcripts. The response patterns under SWL based on transcriptome and metabolome regulation statuses revealed different patterns (additive, dominant, neutral, minor, unilateral, and antagonistic) of transcripts or metabolites that were commonly regulated or expressed uniquely under SWL. Under SWL, the synergistic transcriptional response of several functional gene subsets was positively associated with several metabolomic and physiological responses related to the shutdown of the photosynthetic apparatus and the extensive degradation of starch into saccharides through α-amylase, β-amylase, and α-glucosidase or plastoglobuli accumulation. The dissimilarity between the regulation status and number of transcripts in plants under combined stresses led to nonsynergistic responses in several physiological and phytohormonal traits. As inferred from the impressive synergistic transcriptional response to morpho-physiological changes, combined stresses exhibited a gradually decreasing effect on the changes observed at the molecular level compared to those in the morphological one. Here, by characterizing the molecular responses and patterns of plant species under SWL, our study considerably improves our understanding of the molecular mechanisms underlying combined stress.

Historical disconnection from floodplain alters riparian forest composition, tree growth and deadwood amount

Riparian forests are among the most dynamic but threatened terrestrial ecosystems. Their dynamism and conservation depend on historical changes in river geomorphology, which can be evaluated through changes in channel sinuosity. However, we lack long-term assessments on sinuosity and how they impact riparian forest composition, tree growth and deadwood amount. To fill this research gap, we reconstructed river sinuosity in 14 sites across the middle Ebro basin, north-eastern Spain, using historical aerial photographs taken in 1927, 1956, 1998-2003 and 2014-2015. Relationships between sinuosity, stand composition and deadwood amount and decay degree were calculated. We also reconstructed radial growth of the major tree species (Populus alba, Populus nigra, Fraxinus angustifolia, Salix alba and Ulmus minor) in two sites to evaluate how coupled it was with changes in river flow after dam building. From 1927 to 2015, sinuosity decreased passing from 1.39 to 1.20. The river dynamics were altered in the 1950s and 1960s after dam and dyke building. Sites with high sinuosity values in 1956 corresponded to mature stands with large P. nigra individuals. Sinuosity was negatively related to F. angustifolia (rs = -0.83, p < 0.001) and P. alba (rs = -0.64, p = 0.02) abundance, whereas sites dominated by P. alba and U. minor presented abundant decayed deadwood. A loss of sinuosity and a contraction of the riverbank gradient increased disconnection of active channel from floodplain, with a mixing of more (e.g., P. nigra) and less phreatophytic species (e.g., U. minor). River flow diversion reduced growth and increased the tree-to-tree P. alba growth coherence. Hydrological droughts contributed to growth decline and dieback of U. minor, which is sensitive to spring river flow. Conservation and restoration of riparian forests must consider historical changes in river geomorphology related to human activities.

The interaction between administrative jurisdiction and disturbance on public lands: Emerging socioecological feedbacks and dynamics

Disturbance is one of the fundamental shapers of ecological communities, redistributing resources and resetting successional pathways. Human activities including resources management can influence disturbance regimes and trajectories by actively imposing or suppressing disturbance events or shaping ecosystem recovery via disturbance response. Furthermore, different management objectives may drive different disturbance responses. This suggests that the management jurisdiction to which a land parcel is assigned is likely to influence disturbance management and therefore ecological conditions within that parcel. Here, we combined two exploratory approaches to investigate this linkage. First, we used a systematic literature review to develop a typology of reported disturbance response types and strategies by federal land management agencies in the US. Second, we used Forest Inventory and Analysis (FIA) plot data in five multi-jurisdictional ecosystems containing national parks to investigate the relationship between land ownership and large disturbance occurrence and between disturbance and tree growth rate. We found that agencies vary in the diversity of disturbance response tactics they are reported to employ, and disturbance types vary in the diversity of responses reported in the literature. Disturbance occurrence varied by land ownership type across the FIA dataset, and the direction of tree growth rate was influenced by the interaction between ownership type and disturbance occurrence in two of five examined ecosystems. Although our mixed methods approach was purely exploratory and not mechanistic, our findings suggest that disturbance response is one possible route by which management regimes may influence ecological conditions. Efforts to understand and predict ecological heterogeneity across large landscapes must consider variation in the social system as a potential contributor to such patterns.

Identifying barriers for nature-based solutions in flood risk management: An interdisciplinary overview using expert community approach

The major event that hit Europe in summer 2021 reminds society that floods are recurrent and among the costliest and deadliest natural hazards. The long-term flood risk management (FRM) efforts preferring sole technical measures to prevent and mitigate floods have shown to be not sufficiently effective and sensitive to the environment. Nature-Based Solutions (NBS) mark a recent paradigm shift of FRM towards solutions that use nature-derived features, processes and management options to improve water retention and mitigate floods. Yet, the empirical evidence on the effects of NBS across various settings remains fragmented and their implementation faces a series of institutional barriers. In this paper, we adopt a community expert perspective drawing upon LAND4FLOOD Natural flood retention on private land network (https://www.land4flood.eu) in order to identify a set of barriers and their cascading and compound interactions relevant to individual NBS. The experts identified a comprehensive set of 17 barriers affecting the implementation of 12 groups of NBS in both urban and rural settings in five European regional environmental domains (i.e., Boreal, Atlantic, Continental, Alpine-Carpathian, and Mediterranean). Based on the results, we define avenues for further research, connecting hydrology and soil science, on the one hand, and land use planning, social geography and economics, on the other. Our suggestions ultimately call for a transdisciplinary turn in the research of NBS in FRM.

Application of Ecological Restoration Technologies for the Improvement of Biodiversity and Ecosystem in the River

With global warming, urbanization, and the intensification of human activities, great pressures on river ecosystems have caused ecosystem degradation, the decline in habitats and biodiversity, and the loss of function. Ecological restoration technologies (ERTs) in rivers are effective measures for improving habitat and biodiversity, which has the advantage of recovering ecosystems and biodiversity and promoting the formation of healthy rivers. Several applications of ERTs, including ecological water transfer, fish passage construction, dam removal/retrofit, channel reconfiguration, river geomorphological restoration, natural shoreline restoration, floodplain reconnection, revegetation, etc., are summarized. The classifications of ERTs are highlighted, aiming to distinguish the difference and relationship between structure and the processes of hydrology, physics, geography, and biology. The pros and cons of these technologies are discussed to identify the applicability and limitations on the river ecosystem. In the dynamic processes in the river, these interact with each other to keep ecosystem balance. ERTs are more helpful in promoting the restoration of the natural function of the river, which contribute to the management of river ecological health. Some proposals on river management are suggested. Establishing a unified river health evaluation system will help promote positive feedback on rivers and the further development of ERTs.

Facets and scales in river restoration: Nestedness and interdependence of hydrological, geomorphic, ecological, and biogeochemical processes

Although river restoration has increased rapidly, observations of successful ecological recovery are rare, mostly due to a discrepancy in the spatial scale of the impact and the restoration. Rivers and their ecological communities are a product of four river facets-hydrology, geomorphology, ecology and biogeochemistry-that act and interact on several spatial scales, from the sub-reach to the reach and catchment scales. The four river facets usually affect one another in predictable pathways (e.g., hydrology commonly controls geomorphology), but we show that the order in which they affect each other and can be restored varies depending on ecoregion and hydroclimatic regime. Similarly, processes at different spatial scales can be nested or independent of those at larger scales. Although some restoration practices are dependent of those at higher scales, other reach-scale restoration efforts are independent and can be carried out prior to or concurrently with larger-scale restoration. We introduce a checklist using the four river facets to prioritize restoration at three spatial scales in order to have the largest positive effect on the entire catchment. We apply this checklist to two contrasting regions-in northern Sweden and in southern Brazil-with different anthropogenic effects and interactions between facets and scales. In the case of nested processes that are dependent on larger spatial scales, reach-scale restoration in the absence of restoration of catchment-scale processes can frankly be a waste of money, providing little ecological return. However, depending on the scale-interdependence of processes of the river facets, restoration at smaller scales may be sufficient. This means that the most appropriate government agency should be assigned (i.e., national vs. county) to most effectively oversee river restoration at the appropriate scale; however, this first requires a catchment-scale analysis of feedbacks between facets and spatial scale interdependence.