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Within a metacommunity, both environmental and spatial processes regulate variation in local community structure. The strength of these processes may vary depending on species traits (e.g., dispersal mode) or the characteristics of the regions studied (e.g., spatial extent, environmental heterogeneity). We studied the metacommunity structuring of three groups of stream macroinvertebrates differing in their overland dispersal mode (passive dispersers with aquatic adults; passive dispersers with terrestrial adults; active dispersers with terrestrial adults). We predicted that environmental structuring should be more important for active dispersers, because of their better ability to track environmental variability, and that spatial structuring should be more important for species with aquatic adults, because of stronger dispersal limitation. We sampled a total of 70 stream riffle sites in three drainage basins. Environmental heterogeneity was unrelated to spatial extent among our study regions, allowing us to examine the effects of these two factors on metacommunity structuring. We used partial redundancy analysis and Moran's eigenvector maps based on overland and watercourse distances to study the relative importance of environmental control and spatial structuring. We found that, compared with environmental control, spatial structuring was generally negligible, and it did not vary according to our predictions. In general, active dispersers with terrestrial adults showed stronger environmental control than the two passively dispersing groups, suggesting that the species dispersing actively are better able to track environmental variability. There were no clear differences in the results based on watercourse and overland distances. The variability in metacommunity structuring among basins was not related to the differences in the environmental heterogeneity and spatial extent. Our study emphasized that (1) environmental control is prevailing in stream metacommunities, (2) dispersal mode may have an important effect on metacommunity structuring, and (3) some factors other than spatial extent or environmental heterogeneity contributed to the differences among the basins. We studied three stream macroinvertebrate metacommunities and found that dispersal mode affects metacommunity structuring. Actively dispersing species were more environmentally structured than passively dispersing species. Spatial extent or environmental heterogeneity did not drive the differences among the metacommunities. Our study supports previous findings that species sorting is prevailing in metacommunities.

Climate change is the greatest challenge to modern agriculture. It significantly impacts agricultural systems through an increased frequency and intensity of extreme environmental events. Maize, a vital crop for global food security, is particularly vulnerable to these changes, highlighting the urgent need to develop resilient varieties. This study aims to identify significant genes for adaptation to environmental conditions in 140 individuals derived from 28 Italian maize landraces using a landscape genomics approach to support the development of resilient maize genotypes. Landraces were genotyped using genotyping‐by‐sequencing, and the resulting genetic matrix was used to characterize the collection's diversity. Population genetic studies were conducted to investigate the genetic diversity and structure of the collection. Partial redundancy analysis (pRDA) was subsequently employed to analyze the relationship between climate variables and genetic variation of the materials. Among the 12 ancestral populations identified, both well‐defined populations and highly admixed groups were observed. This degree of admixture was reflected in the clustering analysis and principal component analysis (PCA), although clear differentiation of individual populations was still apparent. pRDA revealed that 30% of the genetic variance in the collection was explained together by climate (45%), geography (11%), and genetic structure (31%). Three potential genomic signals of adaptation were identified in relation to the environmental variability across the sampling sites. The results highlight significant intra‐landrace variability within the examined germplasm and reveal unique landraces tied to ancestral lineages. Notably, we identify distinct genetic markers strongly correlated with environmental factors. This discovery opens new avenues for potential genetic improvement in maize cultivation. Landraces preserve vital traits for the adaptation of maize to environmental stresses, thereby serving as key sources for breeding programs aimed at improving stress tolerance and yield stability under climate change.

Climate, topography, and landscape patterns affect river water quality through processes that influence non-point source pollution. However, little is known about the response of the water quality of rivers on China’s Tibetan Plateau to these environmental factors. Based on the water quality parameters data of the Xoirong River on the Tibetan Plateau in western China, the redundancy analysis and variation partitioning analysis were adopted to determine the main influencing factors affecting river water quality and their spatial scale effects. The major water pollutants were further analyzed using the partial least square-structural equation modeling (PLS-SEM). Another mountainous river with a similar latitude, the same stream order, and low anthropogenic disturbance in central China, the Jinshui River, was also selected for comparative discussion. The results indicated that the overall river water quality on the Tibetan Plateau was superior to that of the Jinshui River. At the catchment scale, the cumulative explanatory powers of the influencing factors of both rivers were greatest. Landscape composition and configuration were the determinant factors for the overall water quality of the two rivers, while the river on the Tibetan Plateau was also significantly affected by climatic and topographical factors. Regarding the main water quality issue, i.e., total nitrogen, agricultural production activities might be the main cause of the river on the Tibetan Plateau. This study unveiled that the river water quality on the Tibetan Plateau is sensitive to climate and topography through comparative studies.

Regional faunas are structured by historical, spatial and environmental factors. We studied large‐scale variation in four ecologically different beetle groups (Coleoptera: Dytiscidae, Carabidae, Hydrophiloidea, Cerambycidae) along climate, land cover and geographical gradients, examined faunal breakpoints in relation to environmental variables, and investigated the best fit pattern of assemblage variation (i.e. randomness, checkerboards, nestedness, evenly spaced, Gleasonian, Clementsian). We applied statistical methods typically used in the analysis of local ecological communities to provide novel insights into faunal compositional patterns at large spatial grain and geographical extent. We found that spatially structured variation in climate and land cover accounted for most variation in each beetle group in partial redundancy analyses, whereas the individual effect of each explanatory variable group was generally much less important in accounting for variation in provincial species composition. We also found that climate variables were most strongly associated with faunal breakpoints, with temperature‐related variables alone accounting for about 20% of variation at the first node of multivariate regression tree for each beetle group. The existence of faunal breakpoints was also shown by the ‘elements of faunal structure’ analyses, which suggested Clementsian gradients across the provinces, that is, that there were two or more clear groups of species responding similarly to the underlying ecological gradients. The four beetle groups showed highly similar biogeographical patterns across our study area. The fact that temperature was related to faunal breakpoints in the species composition of each beetle group suggests that climate sets a strong filter to the distributions of species at this combination of spatial grain and spatial extent. This finding held true despite the ecological differences among the four beetle groups, ranging from fully aquatic to fully terrestrial and from herbivorous to predaceous species. The existence of Clementsian gradients may be a common phenomenon at large scales, and it is likely to be caused by crossing multiple species pools determined by climatic and historical factors on the distributions of species.

An impervious surface is considered one of main factors affecting urban waterlogging. Previous studies found that spatial pattern (composition and configuration) of impervious surfaces affected urban waterlogging. However, their relative importance remains unknown, and the scale-effect of the spatial pattern on urban waterlogging has been ignored. To move forward, our research studied the relationship between spatial patterns on the impervious surface and its subcategories (building and pavement) on urban waterlogging risk spots using Pearson correlation, partial redundancy analysis and performed at three grid scales (1 km × 1 km, 3 km × 3 km, 5 km × 5 km) and the catchment scale based on different spatial resolution land cover maps (2 m, 10 m and 30 m). We identified positively-correlated metrics with urban waterlogging risk spots, such as the composition of impervious surface (i.e., total impervious surface, building, pavement) and the aggregation metric of the total impervious surface at most scales, as well as two negatively correlated metrics (i.e., proximity metric of building, fragmentation metric of total impervious surface). Furthermore, the total variance of urban waterlogging risk spots explained by the spatial pattern of the total impervious surface and its subcategories increased with studied grid and catchment scales while decreasing from a fine to a coarse resolution. The relative contribution of the impervious surface composition and configuration to the variation of urban waterlogging risk spots varied across scales and among impervious surface types. The composition contributed more than the configuration did for the total impervious surface at both grid and catchment scales. Similar to total impervious surface, the composition of buildings was more important than its configuration was at all the grid scales, while the configuration of buildings was more important at the catchment scale. Contrary to the total impervious surface, the configuration of pavement at both the grid and catchment scales mattered more than their compositions did. Furthermore, the composition of the building was more important than that of pavement, but its configuration mattered less. Our study could provide a multi-scale landscape perspective with detailed suggestions for controlling the area of impervious surface and optimizing its spatial configuration in urban waterlogging risk mitigation and urban planning.

Increasing anthropogenic nitrogen (N) emission via different pathways has shown prominent impact on aquatic ecosystems for decades, but the effects of interaction among climate-, landscape- and human-associated variables on riverine DIN (dissolved inorganic nitrogen, mainly NO3− and NH4+) export are unclear. In this study, the data of 43 watersheds with a wide range of climate-, landscape- and human-associated gradients across Taiwan were evaluated with partial redundancy analysis (pRDA) to examine their interactive controls on riverine DIN export. Results show that the annual riverine DIN export in Taiwan is approximately 3100 kg-N km−2 yr−1, spanning from 230 kg-N km−2 yr−1 in less disturbed watersheds (eastern and central Taiwan) to 10,000 kg-N km−2 yr−1 in watersheds with intensive human intervention (southwestern and northern Taiwan). NO3− is generally the single dominant form of DIN, while NH4+ renders significance in disturbed watersheds. Nearly all environmental variables display a positive correlation with DIN export, except for landscape setting variables (e.g., slope, area, channel length), which show a negative relationship. In terms of seasonal pattern, climate and human-landscape variables are related to NO3− export independently in the wet season, yet in the dry season climate-human variables jointly dominate NO3− export. Meanwhile, human-landscape (LH) variables (λ1 of LH > 0.60) control NH4+ exports in both seasons, and human-associated (H) variables (λ1 of H = 0.13) have a minor effect on NH4+ exports in dry season. Precisely, the contribution of controlling variables on DIN export vary with species and seasons, indicating water quality management could be time-dependent, which should be taken into consideration for designing mitigation strategies.

There is a growing need to easily describe and synthesize the dynamics of ecosystems’ components in space and time. Most multivariate analyses provide ordination diagrams or biplots that are too cluttered to allow simple reading and are unfamiliar to most users. To overcome such difficulties, a novel application of principal response curves (PRCs) is proposed. Principal response curves are traditionally used to assess treatment effects on community structure measured repeatedly over time. In this new application, the tested factor and the repeated‐observation axis are replaced by time and space, respectively. The georeferencing of sampling sites permits to produce an easy‐to‐read map that summarizes both the temporal dynamics of the community and the contribution of each species to these dynamics at each sampling site. A 24‐yr‐long time series of scientific surveys monitoring 77 fish and cephalopod species in the Eastern English Channel is used to illustrate the novel application of the PRC method. This new application could prove a relevant tool for the ecosystem approach to human activities management by providing spatialized indicators of community changes, as spatial monitoring tools are increasingly recommended for measuring the effectiveness of management actions.

The wood turtle (Glyptemys insculpta) is a freshwater species endemic to eastern North America and is currently listed as endangered by the International Union for Conservation of Nature. Wood turtle local populations are considered units for the species recovery, and are defined as discrete interbreeding populations in a distinct watershed; however, there are no studies to date supporting this definition. The main objective of this paper was to genetically characterize wood turtles from a northern portion of their range, and test an isolation-by-watershed hypothesis, the first of its kind at such a large geographical scale. Turtles were sampled in 24 watercourses from 12 different watersheds for a total of 331 individuals, each genotyped for nine microsatellite loci. Within each watershed, genetic diversity was similar between sites, and observed heterozygosity ranged from 0.677 to 0.754. Partial redundancy analyses then confirmed that watershed isolation contributed to 18% of the total observed genetic variation, while spatial autocorrelation and the post-glacial Expansion Model did not significantly explain any variation. Clustering methods revealed substantial spatial genetic structure, with sampled groups falling into ten nested hierarchical clusters. We recommend further consideration of these ten clusters to determine if they meet the evolutionary significance criterion to become designatable units, whose genetic structures were influenced by watershed structure.

In the last three decades, several studies have suggested that the structure of stream macroalgal communities is shaped by local environmental variables, but some recent papers have shown that the relevance of the environment on these communities may be overestimated. Using Partial Redundancy Analysis (pRDA), we analyzed macroalgal communities (considering all macroalgae and Phyla Chlorophyta, Cyanobacteria, and Rhodophyta individually) from 105 streams in southern Brazil to test the hypothesis that the relative contributions of the environment and space on the taxonomic composition of these communities is mainly determined by the biological traits and dispersal mechanisms typical for each group. The pRDA showed that the taxonomic composition of the entire community and green algae were explained by both space and environment, whereas for cyanobacteria, only the environment was significant, and for red algae, only space was significant. These divergences in the relative contribution among algal phyla were consistent with our initial hypothesis and can be ascribed to the differences in the ecological features of each group. Our results also support the idea that the community structure of organisms with low dispersal is influenced more significantly by spatial processes, whereas for organisms with high dispersal the local environmental variables are more influential.

An understanding of the interactions between climate change and forest structure on tree growth are needed for decision making in forest conservation and management. In this paper, we investigated the relative contribution of tree features and stand structure on Atlas cedar (Cedrus atlantica) radial growth in forests that have experienced heavy grazing and logging in the past. Dendrochronological methods were applied to quantify patterns in basal-area increment and drought sensitivity of Atlas cedar in the Middle Atlas, northern Morocco. We estimated the tree-to-tree competition intensity and quantified the structure in Atlas cedar stands with contrasting tree density, age, and decline symptoms. The relative contribution of tree age and size and stand structure to Atlas cedar growth decline was estimated by variance partitioning using partial-redundancy analyses. Recurrent drought events and temperature increases have been identified from local climate records since the 1970s. We detected consistent growth declines and increased drought sensitivity in Atlas cedar across all sites since the early 1980s. Specifically, we determined that previous growth rates and tree age were the strongest tree features, while Quercus rotundifolia basal area was the strongest stand structure measure related to Atlas cedar decline. As a result, we suggest that Atlas cedar forests that have experienced severe drought in combination with grazing and logging may be in the process of shifting dominance toward more drought-tolerant species such as Q. rotundifolia.