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ABSTRACT Aim Location Taxon Methods Results Main Conclusions We address the relative importance of biogeographic regions (areas of endemism), regional climate and spatial factors on taxonomic, functional and phylogenetic beta diversity of bird assemblages in upland terra‐firme forests in the Amazon.Amazon biome.Birds.We gathered 27,498 occurrence records of 873 bird species for 115 bird assemblages distributed in all nine biogeographic regions delimited by the major Amazonian rivers. Only data from studies surveying whole communities with standard sampling methods and exhaustive sampling effort were included. We partitioned the fractions of taxonomic, functional and phylogenetic beta diversity explained by climate, biogeographic regions, spatial factors and the variation shared between them.Across the entire Amazon, we found higher total taxonomic (0.68 ± 0.10) than phylogenetic (0.46 ± 0.08) β‐diversity, and low functional β‐diversity (0.34 ± 0.08). Biogeographic regions showed the highest unique contributions explaining taxonomic and phylogenetic β‐total (7% and 5%, respectively) and turnover components (7% of β‐jtu taxonomic, 7% of β‐jtu phylogenetic), but accounted for only 2% of total functional β‐diversity and trait turnover. Climatic variables explained slightly more trait nestedness (5%) compared with species and lineage turnover (3% each). Species composition was clearly distinct between biogeographical regions limited by the Amazon River, but support for the effect of other rivers was mixed.Our study highlights the significant influence of biogeographic regions and climate on species composition in the Amazon. However, our findings also suggest that the Amazon River exerts a more pronounced impact on species distribution compared with other major Amazonian rivers. Species turnover across biogeographical regions is particularly evident at the species level, with minor effects observed in functional traits, suggesting that taxonomic turnover is driven mainly by functionally redundant species. In addition, recent diversification events, occurring predominantly at the tips of the phylogeny without substantial turnover at deeper nodes, are likely responsible for the patchy distribution of species across Amazonia. [ABSTRACT FROM AUTHOR]

Plant communities are impacted by local factors (related to environmental filtering) and landscape factors (related to dispersal limitation). While many studies have shown that the relative importance of these factors in understanding plant community dynamics due to urbanization, little is known about how they are altered by urbanization—a significant threat to biodiversity. This study evaluates the relative importance of local environmental (local factors), landscape, and spatial (landscape factors) variables that influence plant communities in 34 urban green spaces comprising two different habitats (forests and grasslands) along the urban–rural gradients in the Tokyo megacity, Japan. To continuously assess the relative importance of each factor along the urban–rural gradients, we extracted 1000 landscapes within a certain range that contained several sites. Subsequently, the relative importance of each factor and urbanization rate (proportion of artificial built‐up area) were estimated for each landscape. Our study found that the relative importance of both local and landscape factors decreased, while that of local factor for native species in forest habitats and that of landscape factors for native species in grassland habitats increased. Collectively, these findings suggest that city size and habitat characteristics must be considered when predicting changes in plant communities caused by urbanization. [ABSTRACT FROM AUTHOR]

Weed control in winter wheat crops is an important issue. There is a risk of increasing populations of certain weed species that are resistant to some of herbicides used for winter wheat crops. This could be controlled by a combination of agronomic, mechanical, chemical, and biological methods. After introducing winter wheat into the rotation and improving tillage, the weediness of regular black soils with perennial root and emerged weeds were significantly reduced. The formation of nodal and rudimentary roots had a significant effect on the productivity of winter wheat under different soil moisture conditions. The highest yield of winter wheat was obtained when sown at the optimum time, with higher stem density and ear productivity due to better grain fullness. We studied what effects did the tillage methods have on the aggregate state of the soil in relation to weed development in winter wheat crops, finding that the structural and aggregate composition of the soil played an important role in winter wheat crops, influencing both the development of the crop root system and the water-physical balance of the chernozem, as well as naturally influencing the course of erosion processes in the experimental plots, and having a universal dynamic in terms of adaptation of aggregation and disaggregation processes. Prolonged mechanical stress on soil can cause destruction of its structure. For instance, continuous ploughing or moldboardless tillage with little or no manure application may permanently reduce soil fertility by increasing humus mineralisation. Subsequently, these factors may cause a significant decline in the soil's structural and aggregate composition, resulting in larger amounts of dusty particles smaller than 0.25 mm and cloddy particles larger than 10–12 mm. The soil's structural condition before sowing winter wheat in early September, on average for 2011–2016, indicates increased dispersion of the tilth layer (0–10 cm) in the experimental variants where shallow disc tillage of 10–12 cm was applied. Increase in the number of clods larger than 10 mm in the areas where moldboardless tillage had been applied can be attributed to significant soil drainage. The soil's aggregate state was rated as good, with 8.7% in the 0–10 cm soil layer and 1.7% of clods > 10 mm in the 0–30 cm layer. In 2014–2016, it was rated as satisfactory, with 7.4% and 9.8% of clods > 10 mm, respectively. Shallow disc cultivation resulted in slightly worse indicators: 6.6% and 8.3% of clods > 10 mm in soil layer 0–10 cm and 0–30 cm, respectively, in 2011–2013; and 7.2% and 6.9% of clods > 10 mm, respectively, in 2014–2016. In general, the parameters of optimal structural condition were positive. The tillage method used had a considerable effect on weed growth and development, particularly for those with a root and rhizome structure. It also affected the prevalence and development of pests and diseases in winter wheat. Agrotechnical methods of weed control do not guarantee complete destruction of weeds. Mechanical moldboardless tillage to the depth of 14–16 cm and disc tillage to the depth of 10–12 cm left the fields with 4.1 to 8.8 annual weeds per square meter and 1.3 to 3.3 specimens of harmful root weeds such as Convolvulus arvensis, Lactuca tatarica and Cirsium arvense. Mechanical moldboardless tillage to the depth of 14–16 cm and disc tillage to the depth of 10–12 cm left the fields with 4.1 to 8.8 annual weeds per square meter and 1.3 to 3.3 specimens of harmful root weeds such as Convolvulus arvensis, Lactuca tatarica and Cirsium arvense. Post-harvest residues (4–5 t/ha) can provide almost complete protection against weeds by covering the soil surface. However, pests and diseases may spread more easily due to preservation of fungal spores on the surface of plant residues and preservation of pest larvae in the straw and soil. The distribution of weed seeds in the soil was altered when the rotational tillage of common chernozems in winter wheat cultivation technology had been replaced with energy–saving minimum tillage (shallow flat-cutting disc tillage). This resulted in the concentration of most of the weed seeds (85–90%) in the upper soil layer (0–10 cm).

Aim: Invasions of non‐native insects can have substantial impacts on agriculture, forestry, human health and biodiversity with considerable economic and environmental consequences. To understand the causes of these invasions, it is important to quantify the relative influence of principal drivers such as international imports and climatic effects. Location: North America, Chile, Europe, Australia, New Zealand and Japan. Time Period: 1881–2020. Methods: To evaluate the relative contributions of various factors in explaining global variation in numbers of non‐native insect establishments in different world regions, we conducted two multivariate regression analyses to quantify temporal changes in family‐level composition and native ranges of established non‐native species in several world regions. Results: There were temporal changes in the family‐level composition of non‐native species assemblages. Prior to 1900, invasions were dominated by scale insects, subsequently shifting to a more diverse set of species, except in North America, which had relatively small compositional change over time compared to other regions. Spatial and temporal variation in the composition of established species was associated with differences in the origin of imports and climatic factors, each explaining 26.3% and 27.4% of the total variation, respectively. The analysis of native ranges of non‐native species indicated that there was no consistent temporal variation across all regions. Established species in New Zealand were predominantly native to Australasia and species in North America and Chile were mainly from Europe. Non‐native species in Europe mainly originated from the Nearctic region while those in Japan and Australia generally originated from multiple regions. Climatic factors in the destination regions had a primary effect (66.3%) on variation in the native range of established species, although imports also had substantial effects (45.4%). Main Conclusions: Geographical variation in climate and imports act together as drivers of establishment success for non‐native insects in all six regions. [ABSTRACT FROM AUTHOR]

Questions: Numerous studies on community assembly processes have been conducted in natural ecosystems. However, we know little about community assembly processes in human‐dominated urban ecosystems. Here, we asked: (1) how are the composition and functional diversity of native and exotic plant species shaped by local environment and landscape factors across urban vacant lots; and (2) how is microbial (bacterial and fungal) community composition influenced by the local environment, landscape factors, and plant species composition across urban vacant lots? Location: We investigated 69 urban vacant lots in Yokohama, Japan. Methods: By using a variation partitioning approach, we examined the relative importance of local environmental and landscape factors (including land use and spatial structure) in explaining variation in plant species composition and functional diversity of native or exotic species. We also explored the relative importance of local environmental and landscape factors, and plant species composition in explaining variation in microbial community composition. Results: The spatial structure of vacant lots determined the species composition and functional diversity of plant communities, suggesting that plant community assembly is determined by dispersal limitation. However, the functional diversity of the exotic species varied randomly, which reduced the relative importance of the spatial structure of vacant lots. Plant species composition as well as the spatial structure of vacant lots were the important drivers of the composition of soil microbial communities, despite a higher proportion of unexplained variation in their composition. Finally, we found an essential contribution of earthmoving methods in explaining the variations in both plant and microbial community composition. Conclusion: Plant and microbial community composition would be largely determined by dispersal limitation across urban vacant lots. Understanding urban community assembly is critical for predicting plant and microbial communities that play an essential role in regulating urban ecosystem functioning and services. [ABSTRACT FROM AUTHOR]

Aim: Environmental change affects metacommunity structure both directly—via abiotic factors and dispersal that affect species occurrence—and indirectly—via complex interactions among co‐occurring species. We examined how the three main metacommunity factors—environmental conditions, spatial processes and species associations—affect metacommunity structure and whether responses are predictable in real‐world systems by using novel methods to disentangle the drivers. Location: Eastern Asia, northern Europe and central North America. Time period: Contemporary. Major taxa studied: Freshwater fish. Methods: We used a dataset of freshwater fish species occurrences in temperate lakes in three countries in different biogeographic regions. We analysed co‐occurrence patterns by using a joint species distribution model. Results: We demonstrated that environmental processes are the main drivers of species' distribution and diversity, suggesting that future climate change (anthropogenic alteration of abiotic factors) will heavily influence the structure of metacommunities. We also showed that spatial processes and species interactions mediated the influence of environmental processes, especially at the lake level. Main conclusions: Our results indicate that ongoing changes in metacommunity structure are modulated not only by the direct impacts of shifting abiotic factors but also by indirect effects of species interactions. Our global analysis indicates that even under the current high rate of environmental change, an identifiable set of underlying processes can be used to predict impacts of this change on metacommunity structure. [ABSTRACT FROM AUTHOR]

Abstract Plant communities are impacted by local factors (related to environmental filtering) and landscape factors (related to dispersal limitation). While many studies have shown that the relative importance of these factors in understanding plant community dynamics due to urbanization, little is known about how they are altered by urbanization—a significant threat to biodiversity. This study evaluates the relative importance of local environmental (local factors), landscape, and spatial (landscape factors) variables that influence plant communities in 34 urban green spaces comprising two different habitats (forests and grasslands) along the urban–rural gradients in the Tokyo megacity, Japan. To continuously assess the relative importance of each factor along the urban–rural gradients, we extracted 1000 landscapes within a certain range that contained several sites. Subsequently, the relative importance of each factor and urbanization rate (proportion of artificial built‐up area) were estimated for each landscape. Our study found that the relative importance of both local and landscape factors decreased, while that of local factor for native species in forest habitats and that of landscape factors for native species in grassland habitats increased. Collectively, these findings suggest that city size and habitat characteristics must be considered when predicting changes in plant communities caused by urbanization.

Urban greenspaces face significant anthropogenic transformation, impacting soil ecosystems, multifunctionality, and global biodiversity. With increasing population and urbanization, understanding the drivers influencing soil nematode communities in urban greenspaces is crucial for sustainable urban ecosystem management. We chose the campus of The Ohio State University (OSU) due to its unique urban settings with minimally disturbed both turf and non-turf ecosystems. This study focuses on nematodes, the often-overlooked ecological engineers which play diverse roles in ecosystem functions. Nematodes were collected from 99 sampling locations across three soil depths to represent two ecosystem types (i.e., turf and non-turf) of the OSU campus. Among plant parasitic nematodes (PPN), Helicotylenchus and Pratylenchus populations were above damage threshold limits. No specific pattern of community composition was observed in the spatial variation map. The presence of rare PPN genera in the lower soil layers had a significant impact on beta diversity. Trophic group abundances displayed distinct patterns, with turf ecosystems exhibiting higher PPN as well as total nematode abundance decreasing with soil depths. In the subsurface layer (10–30 cm), both bacterivores and fungivores were higher in the non-turf than turf ecosystem. Fungal-dominated decomposition of organic matter was observed in both ecosystem types. Soil physiochemical properties, specifically, total organic carbon and soil texture, had a significant impact on PPN community composition. However, nematode trophic group composition was more altered by ecosystem type than edaphic factors followed by soil depths. Together these three explanatory variables explained 27.5 % of the total variance in trophic group composition. Overall, this study provides insights into the complex interactions between PPN, trophic groups, soil properties, and urban ecosystem characteristics, contributing valuable knowledge for sustainable urban greenspace management.

Both the metabolic theory of ecology and dynamic energy budget theory predict that climate influences body size through its effects on first-order determinants of energetics: reactive temperatures, carbon resources and oxygen availability. Although oxygen is seldom limiting in terrestrial systems, temperature and resources vary spatially. We used redundancy analyses and variation partitioning to evaluate the influence of climatic temperature, precipitation and their seasonalities on multivariate body size across the distributions of four species of the western rattlesnake group in North America (Crotalus pyrrhus, C. scutulatus, C. oreganus and C. viridis). Most species showed a pattern of increased body size in cooler, mesic climates and decreased body size in warmer, xeric climates. Exceptions to the pattern provided additional context through climatic idiosyncrasies in the distributions of each species. For example, the general pattern of a negative influence of temperature on body size was not apparent for C. oreganus, which ranges across the mildest climates overall among the four species. In contrast to previous studies, we found that seasonality had negligible effects on body size. We suggest that precipitation gradients correlate positively with resource availability in driving intraspecific body size and that temperature compounds this gradient by increasing baseline metabolic demands and restricting activity in particularly warm or otherwise extreme climates.

Large-scale vegetation restoration can reduce local watershed water yield, limit vegetation establishment and subsequent growth, and influence regional ecosystem functions. Clipping management by reducing aboveground parts of grassland was gradually recommended and adopted in Grain-for-Green project management to offset these additional issues. Thus, scientific evaluation of the effectiveness of clipping management on infiltration and runoff processes is necessary for maintaining the stability of the surface water system and the sustainability of vegetation restoration in semi-arid regions. A field simulated rainfall experiment was conducted with four managed clipping grasslands (mainly bunge needlegrass and Stipa grandis), including no clipping, light clipping, heavy clipping, and complete clipping under three slope gradients (10, 20, and 30°) and three rainfall intensities (60, 90, and 120 mm/h) to explore the mechanism of runoff and infiltration responses to clipping using structural equation modeling and variation partitioning based on an SCS-CN model. The results showed the runoff coefficient of the light clipping, heavy clipping, and complete clipping plots were 1.33, 2.22, and 4.22 times that of the no clipping plot. The light clipping, heavy clipping, and complete clipping plots decreased the infiltration coefficients by 0%, 5%, and 26% relative to the no clipping plot. Rainfall intensity dominated runoff and infiltration amounts, and clipping intensity's total effect was stronger than slope gradient. Clipping intensity and slope gradient were more influential on runoff with increasing rainfall intensity. The mutual inhibition effect was between clipping intensity and slope gradient on runoff. In order to maintain the sustainability of restoration, a 25–50% vegetation coverage after clipping maximizes the benefits of increasing runoff and maintaining enough soil water supply that prevents possible soil drought. We propose that future vegetation restoration policies should evaluate the appropriate clipping intensity; meanwhile, local physiographic and climate conditions should be considered. These findings may offer guidance for the development of measures for runoff regulation and ecosystem functions of the watershed during vegetation restoration on the northern Loess Plateau.

Although the interaction of water column and sediment variables in streams is intricate, minimal studies have been conducted on how they influence macroinvertebrate community patterns. This study, therefore, aimed to evaluate the influence of water column and sediment variables on macroinvertebrate community patterns in selected Afrotropical streams. Spatiotemporal scales of water column and sediment variables were analysed following standard methods while macroinvertebrates were sampled using the kick sampling technique. Redundancy analysis (RDA) and variation partitioning were used to assess the relationship of macroinvertebrates with water column and sediment variables. Significant differences were observed between seasons amongst water column variables such as total dissolved solids (p=0.046), turbidity (p=0.027), dissolved oxygen (p=0.011), chemical oxygen demand (p=0.002), bank vegetation (p=0.013), velocity (p=0.04), phosphates (p=0.031), and sediment variables such as total organic matter (p=0.01), pH (p=0.024), electrical conductivity (p=0.014). This accounted for the shift in biotic communities across the two seasons. In the studied area and seasons, Baetidae, Chironomidae, and Thiaridae were the most abundant families of macroinvertebrates representing 21.5%, 17.8%, and 6.9% of the 5266 recorded individuals belonging to 68 families. The water column was the most important predictor of macroinvertebrate community patterns (57%) compared to sediments (35%). Therefore, the use of both water column and sediment variables in ecological studies and biomonitoring should be emphasised because the two compartments provide complementary information. This enables researchers to gain a more complete understanding of the ecological health of aquatic habitats, useful in the development of effective management strategies. [ABSTRACT FROM AUTHOR]

Weed control in winter wheat crops is an important issue. There is a risk of increasing populations of certain weed species that are resistant to some of herbicides used for winter wheat crops. This could be controlled by a combination of agronomic, mechanical, chemical, and biological methods. After introducing winter wheat into the rotation and improving tillage, the weediness of regular black soils with perennial root and emerged weeds were significantly reduced. The formation of nodal and rudimentary roots had a significant effect on the productivity of winter wheat under different soil moisture conditions. The highest yield of winter wheat was obtained when sown at the optimum time, with higher stem density and ear productivity due to better grain fullness. We studied what effects did the tillage methods have on the aggregate state of the soil in relation to weed development in winter wheat crops, finding that the structural and aggregate composition of the soil played an important role in winter wheat crops, influencing both the development of the crop root system and the water-physical balance of the chernozem, as well as naturally influencing the course of erosion processes in the experimental plots, and having a universal dynamic in terms of adaptation of aggregation and disaggregation processes. Prolonged mechanical stress on soil can cause destruction of its structure. For instance, continuous ploughing or moldboardless tillage with little or no manure application may permanently reduce soil fertility by increasing humus mineralisation. Subsequently, these factors may cause a significant decline in the soil's structural and aggregate composition, resulting in larger amounts of dusty particles smaller than 0.25 mm and cloddy particles larger than 10–12 mm. The soil's structural condition before sowing winter wheat in early September, on average for 2011–2016, indicates increased dispersion of the tilth layer (0–10 cm) in the experimental variants where shallow disc tillage of 10–12 cm was applied. Increase in the number of clods larger than 10 mm in the areas where moldboardless tillage had been applied can be attributed to significant soil drainage. The soil's aggregate state was rated as good, with 8.7% in the 0–10 cm soil layer and 1.7% of clods > 10 mm in the 0–30 cm layer. In 2014–2016, it was rated as satisfactory, with 7.4% and 9.8% of clods > 10 mm, respectively. Shallow disc cultivation resulted in slightly worse indicators: 6.6% and 8.3% of clods > 10 mm in soil layer 0–10 cm and 0–30 cm, respectively, in 2011–2013; and 7.2% and 6.9% of clods > 10 mm, respectively, in 2014–2016. In general, the parameters of optimal structural condition were positive. The tillage method used had a considerable effect on weed growth and development, particularly for those with a root and rhizome structure. It also affected the prevalence and development of pests and diseases in winter wheat. Agrotechnical methods of weed control do not guarantee complete destruction of weeds. Mechanical moldboardless tillage to the depth of 14–16 cm and disc tillage to the depth of 10–12 cm left the fields with 4.1 to 8.8 annual weeds per square meter and 1.3 to 3.3 specimens of harmful root weeds such as Convolvulus arvensis, Lactuca tatarica and Cirsium arvense. Mechanical moldboardless tillage to the depth of 14–16 cm and disc tillage to the depth of 10– 12 cm left the fields with 4.1 to 8.8 annual weeds per square meter and 1.3 to 3.3 specimens of harmful root weeds such as Convolvulus arvensis, Lactuca tatarica and Cirsium arvense. Post-harvest residues (4–5 t/ha) can provide almost complete protection against weeds by covering the soil surface. However, pests and diseases may spread more easily due to preservation of fungal spores on the surface of plant residues and preservation of pest larvae in the straw and soil. The distribution of weed seeds in the soil was altered when the rotational tillage of common chernozems in winter wheat cultivation technology had been replaced with energy–saving minimum tillage (shallow flat-cutting disc tillage). This resulted in the concentration of most of the weed seeds (85–90%) in the upper soil layer (0–10 cm). [ABSTRACT FROM AUTHOR]

The use of biological indicators in a bioassessment approach is important for inferences of anthropogenic stress in routine monitoring programs. One of the primary assumptions of bioassessment is that biological indicators observed at specific sampling sites will allow for inferences of local environmental quality; however, this assumption requires a reliable understanding of dispersal processes, which is particularly relevant in river systems due to their dendritic network. Inter-stream dispersal between different points of the river network could bias bioassessment, especially for highly mobile organisms like fish. Here, we examine standard biological metrics used in routine biomonitoring to determine how spatial variables, including dispersal, influence inferences between fish populations and environmental gradients. Using redundancy analysis (RDA) and variation partitioning, we tested the relative influence of both environmental and spatial variables on fish community structure and related community metrics. Fish were collected from 99 sampling sites distributed across 44 rivers and streams of the Great Morava River Basin, Serbia. Electroconductivity, the percentage of agricultural areas, dissolved oxygen, ammonia, and nitrate-nitrogen were found to be significant environmental variables, while ten spatial predictors from broad- to small-scales were found to influence fish community structure and community metrics. Our results suggest that contemporary dispersal among streams influences fish community composition, but that trait-based metrics are less sensitive than basic measures of diversity to spatial processes. Our results highlight the need for spatially independent sampling, as well as the need to consider dispersal-based processes in routine biomonitoring. [ABSTRACT FROM AUTHOR]

We studied the community structure of crustacean zooplankton along the biogeographical zones of the St. Lawrence River (Québec, Canada), to evaluate how the riverscale hydrological network formed by water masses, and local-scale aquatic environment, influenced the distribution of crustacean groups (cladocerans, calanoids, cyclopoids and harpacticoids) during the spring (high discharge) and summer (low discharge) hydroperiods. Zooplankton and environmental data were sampled at 52 sites forming 16 transects along the fluvial section zone (FSZ), the fluvial estuary zone (FEZ) and the estuarine transition zone (ETZ) of the St. Lawrence River in May and August 2006. We compared zooplankton community composition among biogeographical zones and fluvial lakes and across the fluvial estuarine continuum. Analyses were carried out using asymmetric eigenvector maps (AEM), redundancy analysis (RDA), and variation partitioning. Spatial distribution patterns revealed a complex river model. Riverscale discontinuities between the fluvial and estuarine transition zones, and the hydrological network of water masses in the fluvial zones, explained better the spatial zooplankton distribution patterns along the fluvial estuarine continuum than the local environment. Spatial variation in the flow network and environmental conditions were the main drivers of zooplankton distributions in spring whereas the flow network of water masses was the most influential factor in summer. [ABSTRACT FROM AUTHOR]

We investigated the relative influence of local environmental and spatial factors in structuring the community composition of fish at 15 sampling sites along the longitudinal gradient of the Lower Niger River Basin (LNRB) in dry and rainy seasons using distance‐based redundancy analysis and variation partitioning analysis. We collected a total of 3807 fish specimens representing 42 species. Our result indicated that the fish community composition differed between the upper and lower regions of the river. The communities in the upper region is influenced by high‐nutrient concentrations, while downstream sites were characterized by high concentrations of suspended solids. Variation partitioning revealed higher contributions of spatial than environmental predictors on fish community composition, with a higher total predicted variance in dry season. The variations in the community composition between upper and lower region may be attributable to the differences in the nature of anthropogenic activities within the regions, which influenced the local conditions differently. Differences in flow dynamics between upper and lower regions as attributable to black and white floods in the LNRB modify the connectivity between sites. Dispersal among sites may be more limited downstream than in the upper region, particularly in the dry season, because damming in the upper region also interrupts the natural flood regime such that there are low water levels in the lower region, which spatially isolate fish communities at certain sampling sites. The relatively higher total predicted variance during dry season may be attributable to the temporal differences in abiotic conditions between sites, which may have influenced site level community composition and abundance differently. [ABSTRACT FROM AUTHOR]

Spatial and environmental processes are two ecological processes that have attracted considerable attention in plant community assembly, depending on sampling scale and life history. However, the processes that determine community assembly have not been studied in the karst region of southwest China. In this study, a 25-ha (500 m × 500 m) monitoring plot within the subtropical climax forest in the karst region was established and canonical correspondence analysis was used to reveal the effects of topography and soil on the spatial patterns of tree community assembly. Our study suggests that spatial processes dominate species composition and the combined effects of spatial and environmental processes play an important role. Overall interpretation rate increases with enlarging the sampling scale. However, the pattern of variation partitioning was similar in different life stages. Environmental variables significantly affected species composition at different sampling sizes and life histories and had a higher interpretation rate of species composition on larger sampling sizes. Topographic wetness index was the most important variable to explain species composition of the environmental variables. These results suggest that it is necessary to consider the relative importance of environmental and spatial factors on community assembly to better understand, conserve, and manage subtropical karst forests. [ABSTRACT FROM AUTHOR]

An urgent aim of ecology is to understand how key species relate to climatic and environmental variation, to better predict their prospects under future climate change. The abundant dwarf shrub bilberry (Vaccinium myrtillus L.) has caught particular interest due to its uphill expansion into alpine areas. Species' performance under changing climate has been widely studied using the climatic space‐for‐time approach along elevation gradients, but potentially confounding, local environmental variables that vary along elevation gradients have rarely been considered. In this study, performed in 10 sites along an elevation gradient (200–875 m) in W Norway, we recorded species composition and bilberry performance, both vegetative (ramet size and cover) and reproductive (berry and seed production) properties, over one to 4 years. We disentangled effects of local environmental variables and between‐year, climatic variation (precipitation and temperature), and identified shared and unique contributions of these variables by variation partitioning. We found bilberry ramet size, cover and berry production to peak at intermediate elevations, whereas seed production increased upwards. The peaks were less pronounced in extreme (dry or cold) summers than in normal summers. Local environmental variables explained much variation in ramet size and cover, less in berry production, and showed no relation to seed production. Climatic variables explained more of the variation in berry and seed production than in ramet size and cover, with temperature relating to vegetative performance, and precipitation to reproductive performance. Bilberry's clonal growth and effective reproduction probably explain why the species persists in the forest and at the same time invades alpine areas. Our findings raise concerns of the appropriateness of the climatic space‐for‐time approach. We recommend including both climatic and local environmental variables in studies of variation along elevation gradients and conclude that variation partitioning can be a useful supplement to other methods for analysing variation in plant performance. [ABSTRACT FROM AUTHOR]

Abstract An urgent aim of ecology is to understand how key species relate to climatic and environmental variation, to better predict their prospects under future climate change. The abundant dwarf shrub bilberry (Vaccinium myrtillus L.) has caught particular interest due to its uphill expansion into alpine areas. Species' performance under changing climate has been widely studied using the climatic space‐for‐time approach along elevation gradients, but potentially confounding, local environmental variables that vary along elevation gradients have rarely been considered. In this study, performed in 10 sites along an elevation gradient (200–875 m) in W Norway, we recorded species composition and bilberry performance, both vegetative (ramet size and cover) and reproductive (berry and seed production) properties, over one to 4 years. We disentangled effects of local environmental variables and between‐year, climatic variation (precipitation and temperature), and identified shared and unique contributions of these variables by variation partitioning. We found bilberry ramet size, cover and berry production to peak at intermediate elevations, whereas seed production increased upwards. The peaks were less pronounced in extreme (dry or cold) summers than in normal summers. Local environmental variables explained much variation in ramet size and cover, less in berry production, and showed no relation to seed production. Climatic variables explained more of the variation in berry and seed production than in ramet size and cover, with temperature relating to vegetative performance, and precipitation to reproductive performance. Bilberry's clonal growth and effective reproduction probably explain why the species persists in the forest and at the same time invades alpine areas. Our findings raise concerns of the appropriateness of the climatic space‐for‐time approach. We recommend including both climatic and local environmental variables in studies of variation along elevation gradients and conclude that variation partitioning can be a useful supplement to other methods for analysing variation in plant performance.

Anthropogenic land cover change in watersheds has the potential to degrade stream habitat quality and alter fish assemblage structure. The objective of this study was to examine the relative importance of urbanization at different spatial scales and local habitat conditions on both the fish taxonomic assemblage and trait assemblage. Fish assemblages were sampled in 22 wadeable streams within a single sub-basin in the northeastern USA. Urbanized land cover at the watershed and riparian scales was associated with increases in specific conductivity and pH, but was not a major determinant of taxonomic or trait assemblage structure. Instead, taxonomic and trait assemblages were associated with a gradient of decreasing elevation and increasing temperature, and some of the most urbanized sites supported diverse and unique fish assemblages. These results contribute to a greater understanding of the variation in the effects of urbanization on stream health. [ABSTRACT FROM AUTHOR]

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The changes of agriculture led to deep transformations of arable plant diversity. The features of arable plant communities are determined by many anthropic, environmental, and geographic drivers. Understanding the relative importance of such drivers is essential for conservation and restoration purposes. In this work, we assessed the effects of agronomic, climatic, geographic, and landscape features on α-diversity, β-diversity, and composition of winter arable plant communities across continental Italy, a European hotspot of arable plant diversity. Using redundancy analysis and variation partitioning, we observe that the selected groups of variables explained a restrained to moderate proportion of the variation in diversity and composition, depending on the response (5.5–23.5%). We confirm previous evidence that climate and geographic location stand out in determining the features of arable plant communities in the country, followed by the type of rural area. The surrounding landscape has a subordinate influence but affects both α and β-diversity. The α-diversity is higher in traditional agricultural areas and in landscapes rich in woody vegetation, while it is lower in warmer areas. Species composition is determined by climate, latitude, and the type of rural area, but not by landscape. Total β-diversity is mainly explained by climate and latitude, and subordinately by the agricultural context and landscape. Its components are explained by latitude and climate (replacement) and agricultural context and climate (richness difference). The local contribution to β-diversity of single sites suggested a good conservation status of the studied communities. We discuss the implications of our findings in the light of conservation and restoration of vanishing arable plant communities. [ABSTRACT FROM AUTHOR]

Aims and background: Groundwater-dependent minerotrophic fens are globally threatened biodiversity hotspots. The supply of groundwater keeps their soil thermally stable and mitigates climatic extremes by thermal buffering. This stability has been shown to influence species composition variation at the between-site scale but has not been studied at the within-site scale. Methods: A total of 19 calcareous fens in the Western Carpathians were sampled for bryophytes, vascular plants, and terrestrial snails with three plots at each site along a watertable gradient, i.e. from the most waterlogged (plot A) through intermediately waterlogged (plot B) to the most terrestrial (plot C) areas. Temperature dataloggers were buried in each plot, and climate variables were derived from the climate database. Results: Water table depth and soil temperature were the most important factors influencing species composition. Significant differences were found between spring source area (A) and fen margin (C) plots for all taxa groups studied. Soil temperature played a significant role at the site level only for bryophytes and vascular plants. However, a large overlap between water table depth and soil temperature for bryophytes also suggests a synergistic effect of these two factors. Conclusion: Soil temperature plays an important role in promoting compositional variation of vegetation on the within-site scale (i.e. a pure effect of soil temperature) in groundwater-dependent mires, as we show here for the first time. This is essential in the light of ongoing climate change. Conservation measures should primarily focus on bryophytes as they are the most temperature-sensitive organisms and important ecosystem engineers. [ABSTRACT FROM AUTHOR]

Elevational gradient, slope, and aspect offer a unique opportunity to explore the response of plant species under changing environmental conditions. The present study aimed to analyze the species diversity and distribution patterns with respect to altitude, aspect, and habitat types in the Kashmir Himalayas. Considering major aspects and habitats, a total of 123 representative sites were selected along the elevational gradients for the present study. The plant species composition of each selected site was studied by organized sampling following the standard ecological methods. During the present study, a total of 361 vascular plant species belonging to 71 families and 214 genera were identified in the study area. At the lower altitudes, the southern aspect and drier habitats showed the highest diversity. Moreover, a significant amount of compositional dissimilarity was observed between the studied aspects, habitats, and elevation belts and was mainly due to species turnover rather than the nestedness component. Further, among the studied variables, altitude was the most important contributing variable, explaining the greatest variation in the species composition. The paired effects of altitude and habitat explained the maximum variation in plant species composition. It may be concluded that floristic diversity should be studied not only with reference to elevational gradients but should also include aspects and habitats. The current study will act as a reference in this direction. A similar study must be replicated in other parts of the Himalayan region in the future to improve our understanding of the distribution and preferences of plant species in mountainous zones. This, in turn, will be immensely helpful in the conservation and sustainable utilization of resources in these ecologically fragile regions.

We evaluated the relative importance of environmental and spatial variables in structuring tadpole metacommunities at three hierarchical spatial scales in two ecoregions of the Atlantic Forest. Tadpole communities were generally more spatially structured at larger spatial scales. Environmental filtering processes seemed to be equally important at both large and small scales, however, spatially structured environmental variables were more important at larger scales, whereas non-spatially structured ones were more important at smaller scales. The importance of local environmental filters was also greater in the ecoregion that exhibits harsher environmental conditions, such as higher intensity of land-use patterns and dryer climate. This may indicate a greater role for stochastic assembly processes in more benign environments. Species co-occurrence patterns at the larger spatial scale mostly indicated biogeographical differences between the two ecoregions in a Clementsian structure, exhibiting two clear groups of species composition. Co-occurrence patterns at the smallest spatial scale were coherent only when strong environment gradients such as canopy cover were present. However, at the intermediate spatial scale the metacommunities became consistently non-coherent suggesting that species may be responding to processes acting at different spatial scales. [ABSTRACT FROM AUTHOR]

Taxonomic distinction of species forms the foundation of biodiversity assessments and conservation priorities. However, traditional morphological and/or genetics-based taxonomic assessments frequently miss the opportunity of elaborating on the ecological and functional context of species diversification. Here, we used 3D geometric morphometrics of the cranium to improve taxonomic differentiation and add ecomorphological characterization of a young cryptic divergence within the carnivorous marsupial genus Antechinus. Specifically, we used 168 museum specimens to characterize the recently proposed clades A. stuartii 'south', A. stuartii 'north' and A. subtropicus. Beyond slight differences attributable to overall size (and, therefore, not necessarily diagnostic), we also found clear allometry-independent shape variation. This allowed us to define new, easily measured diagnostic traits in the palate, which differentiate the three clades. Contrary to previous suggestions, we found no support for a latitudinal gradient as causing the differentiation between the clades. However, skull shape co-varied with temperature and precipitation seasonality, suggesting that the clades may be adapted to environmental variables that are likely to be impacted by climate change. Our study demonstrates the use of 3D geometric morphometrics to improve taxonomic diagnosis of cryptic mammalian species, while providing perspectives on the adaptive origins and potential future threats of mammalian diversity. [ABSTRACT FROM AUTHOR]

Abiotic factors play important roles on the habitat preferences and dispersal decisions of species. The objective of this study was to estimate the groups of abiotic variables best explaining the variation of ostracods species taken from 31 water bodies (27 streams and 4 lakes) sampled twice (October 2020 and April 2021) in the Eastern Mediterranean region of Turkey. In this study, a total of 34 ostracod taxa (24 recent and 10 sub-fossil) were reported, and Ilyocypris bradyi and Prionocypris zenkeri were the most common species occurred more than 10 times. Based upon to the variation partitioning analysis, dissolved oxygen+elevation+magnesium (DO+Elev+Mg2+) was the best model with 12.66% explanation power in the variations of ostracod species in the present study. The distance-based redundancy analysis elucidated 14.1% of the total variation in the species distribution matrix that was significantly affected by Mg2+ and Elev. The effectiveness of variables on the occurrence of species was tested by Generalized Linear Models resulted in positive roles of Elev for Psychrodromus olivaceus, Neglecandona neglecta and Pseudocandona albicans, Ca2+ for Cyprideis torosa and P. albicans, and DO for P. olivaceus, but negative roles of Tw for N. neglecta and P. albicans, Ca2+ for Herpetocypris helenae, and DO for N. neglecta. A positively significant association was found between high Mg2+ values and the abundance of P. zenkeri. Results suggest that effectiveness rates of environmental factors on the occurrence of species can change according to ecoregional differences when the variables are evaluated in the analyses together. Therefore, especially ecoregion-based ecological information of species should be determined for better inferences about the ecological preferences of species. [ABSTRACT FROM AUTHOR]

Worldwide, forest fragmentation and degradation have affected the flora and fauna, and are threatening the livelihood of people depending upon forest resources. It is essential to understand the underlying ecological processes to better manage such landscapes. In ecological assessments, insects are useful tools to assess the effects of human interventions such as restoration, as insects are vital for several ecosystem processes. Therefore, we studied the ecological processes that determined the distributions of the epigeic insect communities among the degraded forest fragments of the Attappady Hills (Western Ghats, India), which are being restored. Our objectives were to determine the spatial variations in the epigeic insect communities and their responses to habitat quantity and quality of the forest fragments, along with an assessment of the invasive ants' responses to fragmentation and degradation, and their effects on the native insect communities. We used pitfall traps in several forest fragments representing varying disturbance levels along an east–west gradient. The diversity of various insect taxonomic groups and functional feeding guilds were higher in smaller fragments than compared to larger fragments due to edge effects. The variations in the distributions of insect communities were explained by the habitat features that were spatially correlated. Invasive ants, Anoplolepis gracilipes, infested the smaller fragments where the vegetation quality had degraded. We conclude that an understanding of the effects of fragmentation and degradation on insect communities is vital to restoration managers as ecological restoration becomes an important strategy to reverse degradation and to revive ecological processes of fragmented forests. Abstract in Malayalam is available with online material. [ABSTRACT FROM AUTHOR]

Earthworm communities within urban environments remain an intriguing subject. This study aims to unravel the intricate relationship between these communities and the heterogeneous urban soils they inhabit. Urban soils, shaped by past and present human activities, harbor a rich diversity of earthworms, yet the specific factors influencing these communities remain poorly understood. Earthworm communities were sampled across 13 urban parks of Montpellier, a Mediterranean city in France. The effect of four variables at two scales were assessed: (i) landscape attributes within a 100-meter radius surrounding each sampling point and (ii) site-specific factors, including soil properties such as organic carbon content and pH levels, soil age, and management practices. Variation partitioning was employed through partial canonical correspondence analysis in order to disentangle the effects of these variables on earthworm community composition. A total of 16 species were identified out of 1270 individuals collected. Most are ubiquist, with a limited number being endemic to the Mediterranean region, potentially indicating biotic homogenization due to urbanization. In addition, multivariate analyses emphasized the substantial influence of landscape characteristics, composed by the rate of green spaces and the number of patches. These landscape-level attributes and especially the connectivity of green spaces emerged as primary drivers, surpassing the influence of management practices, soil age and soil properties. Thus, this research underscores the importance of considering diverse scales, and particularly landscape-level factors, in comprehending and restoring soil fauna such as earthworm communities within Mediterranean urban parks. [ABSTRACT FROM AUTHOR]

• Nematode abundance decreases with depth, impacted by texture, organic carbon and micro-nutrients. • Urban turfgrasses are confronted with substantial threats from plant-parasitic nematodes (PPN), like Helicotylenchus and Pratylenchus. • Soil physiochemical properties shape PPN community composition. • PPN community composition showed spatial heterogeneity. • Understanding nematode ecology contributes to sustainable urban ecosystem management. Urban greenspaces face significant anthropogenic transformation, impacting soil ecosystems, multifunctionality, and global biodiversity. With increasing population and urbanization, understanding the drivers influencing soil nematode communities in urban greenspaces is crucial for sustainable urban ecosystem management. We chose the campus of The Ohio State University (OSU) due to its unique urban settings with minimally disturbed both turf and non-turf ecosystems. This study focuses on nematodes, the often-overlooked ecological engineers which play diverse roles in ecosystem functions. Nematodes were collected from 99 sampling locations across three soil depths to represent two ecosystem types (i.e., turf and non-turf) of the OSU campus. Among plant parasitic nematodes (PPN), Helicotylenchus and Pratylenchus populations were above damage threshold limits. No specific pattern of community composition was observed in the spatial variation map. The presence of rare PPN genera in the lower soil layers had a significant impact on beta diversity. Trophic group abundances displayed distinct patterns, with turf ecosystems exhibiting higher PPN as well as total nematode abundance decreasing with soil depths. In the subsurface layer (10–30 cm), both bacterivores and fungivores were higher in the non-turf than turf ecosystem. Fungal-dominated decomposition of organic matter was observed in both ecosystem types. Soil physiochemical properties, specifically, total organic carbon and soil texture, had a significant impact on PPN community composition. However, nematode trophic group composition was more altered by ecosystem type than edaphic factors followed by soil depths. Together these three explanatory variables explained 27.5 % of the total variance in trophic group composition. Overall, this study provides insights into the complex interactions between PPN, trophic groups, soil properties, and urban ecosystem characteristics, contributing valuable knowledge for sustainable urban greenspace management. [ABSTRACT FROM AUTHOR]

Simple Summary: The objectives of our study were to determine the seasonal home range size variation, and to determine the fraction of variation in home range use explained by environmental variables. We found that the core home range size of the golden snub-nosed monkey in Tangjiahe National Nature Reserve varied seasonally. The environmental variables in spring and summer explained a large part of home range use intensity, while the environmental variables in autumn and winter explained a moderate fraction and no fraction of home range use intensity, respectively. Water sources, tree density, and dominant trees of Chinese wingnut (Pterocarya stenoptera) were the important environmental factors determining home range use. Accurate descriptions of home ranges can provide important information for understanding animal ecology and behavior and contribute to the formulation of conservation strategies. We used the grid cell method and kernel density estimation (KDE) to estimate the home range size of golden snub-nosed monkeys (Rhinopithecus roxellana) in Tangjiahe National Nature Reserve. We also used Moran's eigenvector maps analysis and variation partitioning to test the influence of environmental variables on home range use. The seasonal home range size was 15.4 km2 in spring, 11.6 km2 in summer, 13.7 km2 in autumn, and 15.6 km2 in winter, based on the grid cell method. The seasonal core area of 50% KDE was 9.86 km2 in spring, 5.58 km2 in summer, 7.20 km2 in autumn, and 4.23 km2 in winter. The environmental variables explained 63.60% of home range use intensity in spring, 72.21% in summer, 26.52% in autumn, and none in winter, and some environmental variables contributed to the spatial variation in home range use intensity. Water sources, tree density, and dominant trees of Chinese wingnut (Pterocarya stenoptera) were the important environmental factors determining home range use. These environmental factors require protection to ensure the survival of the golden snub-nosed monkey. [ABSTRACT FROM AUTHOR]

Portulaca hatschbachii is endemic to the basaltic rocky outcrops that are distributed, in a discontinuous way, along the Third Plateau of Paraná State, Brazil, composing environments that form the Subtropical Highland Grasslands of the Atlantic Forest Biome. Considering the risk of extinction of the species and the massive anthropization of these outcrops, we applied AFLP, ITS and rps16 molecular markers in ten populations throughout the area of occurrence of the species to generate information about the genetic status of P. hatschbachii and contribute to the development of conservation strategies. Low rates of genetic diversity, high population structure, restricted gene flow and the presence of diversifying selection were observed for the populations. The analysis of variation partitioning (R2adj. = 63.60%) showed that environmental variables have a greater influence on the distribution of variation of loci under selection (R2adj. = 26.70%) than geographical isolation (R2adj. = 1.20%). The strong population structure, for both neutral and selected loci, suggests an isolation by adaptation mechanism (IBA) occurring in populations and highlights the need and urgency for in situ conservation plans for the species and its occurrence on rocky outcrops. [ABSTRACT FROM AUTHOR]

Understanding temporal variation in mechanisms and factors shaping metacommunity is an important issue of community ecology. The relative importance of different assembly mechanisms, such as dispersal and environmental filtering, can vary through time in dynamic systems, whereas it is still unclear how different dispersal modes affect temporal patterns of the variation. We investigated metacommunity structures of fish and aquatic insects with flying adults in spring, summer, and autumn in drainage ditches of paddy fields in the Kita River basin, Japan, where agricultural water management and flood events cause seasonal flow changes. Using redundancy analysis and variation partitioning, we examined how the variation of these metacommunity structures was explained by local environmental factors and two types of spatial factors (overland based and watercourse based). Fish metacommunities were mainly influenced by local environmental factors (e.g., water depth) in summer, and by watercourse‐based spatial factors (e.g., distance to downstream rivers) in spring and autumn. As fishes are obligate aquatic dispersers, increased hydrological connectivity among habitats in summer weakens the dispersal limitation from downstream rivers and enables species to track environmentally preferred habitats. In contrast, only overland‐based spatial factors (e.g., spatial patterns based on overland distance) significantly affected aquatic insect metacommunities in summer and autumn. These results suggest that regional and landscape variables can influence their metacommunity patterns more than the local environment. We conclude that the dynamic nature of the environment and dispersal modes can interactively influence metacommunity structures in temporally connecting habitats. [ABSTRACT FROM AUTHOR]

Trentepohliales are a group of both free‐living and lichenized algae, with most diversity occurring in tropical regions. Recent studies showed that the abundance of lichens with a trentepohlioid photobiont has been increasing in temperate habitats, probably because of global warming, which makes them an interesting study case. A detailed molecular study of the diversity of lichenized Trentepohliales, epiphytic as well as epilithic, was performed in three forests of north‐western Europe. Additional samples of lichens of the Arthoniales order (associating essentially with a trentepohlioid photobiont) from other European regions and from other continents were also sequenced. A total of 195 algal sequences were obtained. Phylogenetic analyses with rbcL and ITS loci were performed and associations between phylogenetic distances of photobionts and ecological factors (substratum, climate or Wirth indices, mycobiont taxonomy, and geographic location) were tested by variation partitioning and phylogenetic signal analyses. The high number of rbcL algal haplotypes found in some lichens or on different substrata revealed that the Trentepohliales diversity in extratropical regions was underestimated. The phylogenetic patterns showed selectivity of some photobionts in their fungal partner choice and vice‐versa, while others were linked with several haplotypes. Photobionts seemed to be less selective than mycobionts. The main factors influencing lichenized algal community were climate and mycobiont species. Coevolution between mycobionts and photobionts as well as switching between free living and lichenized lifestyles appeared to drive the evolution of Trentepohliales and might explain the high cryptic diversity observed, which might be changing in some regions due to climate change. [ABSTRACT FROM AUTHOR]

Both the metabolic theory of ecology and dynamic energy budget theory predict that climate influences body size through its effects on first-order determinants of energetics: reactive temperatures, carbon resources and oxygen availability. Although oxygen is seldom limiting in terrestrial systems, temperature and resources vary spatially. We used redundancy analyses and variation partitioning to evaluate the influence of climatic temperature, precipitation and their seasonalities on multivariate body size across the distributions of four species of the western rattlesnake group in North America ( Crotalus pyrrhus , C. scutulatus , C. oreganus and C. viridis ). Most species showed a pattern of increased body size in cooler, mesic climates and decreased body size in warmer, xeric climates. Exceptions to the pattern provided additional context through climatic idiosyncrasies in the distributions of each species. For example, the general pattern of a negative influence of temperature on body size was not apparent for C. oreganus , which ranges across the mildest climates overall among the four species. In contrast to previous studies, we found that seasonality had negligible effects on body size. We suggest that precipitation gradients correlate positively with resource availability in driving intraspecific body size and that temperature compounds this gradient by increasing baseline metabolic demands and restricting activity in particularly warm or otherwise extreme climates., Competing Interests: We declare we have no competing interests., (© 2024 The Authors.)

Vegetation composition and/or plant species co-existence is influenced by the environmental variations in any region. The ecological knowledge and order of importance of selected environmental variations is important in conservation and management of plant resources. Based on relevant knowledge gap, the study area of district Jhelum, Pakistan lying in an arid-tropical zone was selected to explore the vegetation types and their driving environmental factors by using latest multivariate statistical approaches. For this, the entire district was ecologically explored to collect the natural wild vegetation and environmental data from January 2018 to December 2020. The study area was partitioned into 171 grids (5 × 5 km2). In each grid, three sites were randomly selected (i.e. 513 samples), and subsequently-nine plots were laid at each sampling site (i.e. 1539 plots). Different statistical tests including Monte Carlo permutation test, Indicator Species Analysis (ISA), hierarchical classification, ordination, and variation partitioning were applied to seek the potential number of vegetation types, plant species composition, classification of the studied samples, order of importance of the considered predictors and groups of environmental variables respectively. The findings of this study indicated that all the documented 291 plant species belong to five statistically significant (p

Fungi in the family Xylariaceae are primary agents of leaf litter decomposition. However, the diversity of carbon source utilization by xylariaceous fungi and the relative effects on this from environmental and phylogenetic factors are largely unknown. This study assessed the metabolic diversity and redundancy of xylariaceous fungi, associated with leaf litter decomposition, by measuring their in vitro capacity to utilize multiple carbon sources. The work identified the relative influences of geographic and climatic sources, as well as the taxonomic and phylogenetic relatedness, of the fungi. Using Biolog EcoPlateTM, 43 isolates belonging to Nemania, Xylaria, Nodulisporium, Astrocystis, and Hypoxylon, isolated from Castanopsis sieboldii leaf litter at eight sites in Japan, were found to have the capacity to utilize a variety of carbohydrates, amino acids/amines, carboxylic acids, and polymers. The genera of xylariaceous fungi and their origins significantly affected their metabolic diversity and utilization of carbon sources. Variation partitioning demonstrated that dissimilarities in carbon utilization among fungal isolates were mostly attributable to site differences, especially climatic factors: mean annual temperature and precipitation, and maximum snow depth. Moreover, xylariaceous isolates that originated from adjacent sites tended to have similar patterns of carbon source utilization, suggesting metabolic acclimation to local environmental conditions. [ABSTRACT FROM AUTHOR]

Beta(β)‐diversity, or site‐to‐site variation in species composition, generally decreases with increasing latitude, and the underlying processes driving this pattern have been challenging to elucidate because the signals of community assembly processes are scale‐dependent. In this meta‐analysis, by synthesising the results of 103 studies that were distributed globally and conducted at various spatial scales, we revealed a latitudinal gradient in the detectable assembly processes of vascular plant communities. Variations in plant community composition at low and high latitudes were mainly explained by geographic variables, suggesting that distance decay and dispersal limitations causing spatial aggregation are influential in these regions. In contrast, variation in species composition correlated most strongly with environmental variables at mid‐latitudes (20–30°), reflecting the importance of environmental filtering, although this unimodal pattern was not statistically significant. Importantly, our analysis revealed the effects of different spatial scales, such that the correlation with spatial variables was stronger at smaller sampling extents, and environmental variables were more influential at larger sampling extents. We concluded that plant communities are driven by different community assembly processes in distinct biogeographical regions, suggesting that the latitudinal gradient of biodiversity is created by a combination of multiple processes that vary with environmental and species size differences. [ABSTRACT FROM AUTHOR]

In metacommunity ecology, a major focus has been on combining observational and analytical approaches to identify the role of critical assembly processes, such as dispersal limitation and environmental filtering, but this work has largely ignored temporal community dynamics. Here, we develop a "virtual ecologist" approach to evaluate assembly processes by simulating metacommunities varying in three main processes: density‐independent responses to abiotic conditions, density‐dependent biotic interactions, and dispersal. We then calculate a number of commonly used summary statistics of community structure in space and time and use random forests to evaluate their utility for inferring the strength of these three processes. We find that (i) both spatial and temporal data are necessary to disentangle metacommunity processes based on the summary statistics we test, and including statistics that are measured through time increases the explanatory power of random forests by up to 59% compared to cases where only spatial variation is considered; (ii) the three studied processes can be distinguished with different descriptors; and (iii) each summary statistic is differently sensitive to temporal and spatial sampling effort. Including repeated observations of metacommunities over time was essential for inferring the metacommunity processes, particularly dispersal. Some of the most useful statistics include the coefficient of variation of species abundances through time and metrics that incorporate variation in the relative abundances (evenness) of species. We conclude that a combination of methods and summary statistics is probably necessary to understand the processes that underlie metacommunity assembly through space and time, but we recognize that these results will be modified when other processes or summary statistics are used. [ABSTRACT FROM AUTHOR]

Urban areas are strongly transformed by the human population and these environmental changes can affect the richness and composition of invasive alien trees (IAT) across cities. In this study, we investigate the role of urbanization and climate variables on richness and species composition of IAT in cities from Brazil. We investigated (i) the relative contribution and how variables related to urbanization affects the patterns of richness and composition; and (ii) the relative contribution and how variables related to climate affects richness and composition of IAT. Thus, we used occurrences of IAT in 93 urban areas in Brazil gathered from 130 references. We tested the variation partitioning using three models with variables related to urbanization, climate, and spatial correlation for richness and species composition of IAT. Next, we tested the significance of each set of variables on the richness and species composition of IAT. Urbanization variables explained 18% of the variation in species richness of IAT, whereas climate explained 18% of the variation in species composition of IAT. Demographic density (habitants per km2) positively affected the richness of IAT, whereas the percentage of urban forest influenced species composition. Köppen climate zones affected richness while the covariate temperature annual range had a negative effect on richness. Temperature annual range, annual precipitation, precipitation of driest quarter, and precipitation of warmest quarter affected the species composition of IAT. We confirmed urban variables have a relevant influence on species richness, but climate variables are still important to understand the composition of IAT across cities. Thus, species richness is affected at a local scale by urbanization, and species composition by climate at broader scales. [ABSTRACT FROM AUTHOR]

Our understanding of the factors determining stream community assembly has mainly been built upon taxonomic diversity. Additionally, most investigations of factors governing assembly are limited in scope and use of spatial model testing. Therefore, we combine a sizeable environmental dataset (local and landscape level) with robust spatial analysis to model the factors determining multiple facets of stream fish diversity—across a region and within four drainages. We found that total dissimilarity was more explained by replacement than nestedness. Fish diversity was governed by spatial and environmental factors, although the degree depended on the diversity facet and drainage. Adjusted R2 for combined models (i.e., spatial plus environment) of fish beta diversity was as high as 0.65. Local instream habitat variables were the most explanatory factors. Spatial factors based on overland Euclidean distance and asymmetric (directional) distance revealed more explanatory power than symmetric hydrologic distance. The purely spatial variation was often as high as 33% explained. Multiple facets were strongly correlated and provided similar results—albeit some differences arose, especially within different drainages; these differences highlight how difficult it is to generalize the multifaceted approach. However, the importance of exploring spatial models for determining the role of spatial processes on community assembly cannot be overstated. [ABSTRACT FROM AUTHOR]

Community ecologists and macroecologists have long sought to evaluate the importance of environmental conditions in determining species distributions, community composition, and diversity across sites. Different methods have been used to estimate species–environment relationships, but their differences to jointly fit and disentangle spatial autocorrelation and structure remain poorly studied. We compared how methods in four broad families of statistical models estimated the contribution of the environment and space to variation in species occurrence and abundance. These methods included redundancy analysis (RDA), generalized linear models (GLMs), generalized additive models (GAMs), and three types of tree‐based machine learning (ML) methods: boosted regression trees (BRT), random forests, and regression trees. The spatial component of the model consisted of Moran's eigenvector maps (MEMs; in RDA, GLM, and ML), smooth spatial splines (in GAM), or tree‐based nonlinear modeling of spatial coordinates (in ML). We simulated typical site‐by‐species data to assess the methods' performance in (1) fitting environmental and spatial models, and (2) partitioning the variation explained by environmental and spatial predictors. We observed marked differences in performance among methods generally caused by their different performances in fitting spatial structures. Generalized linear model and BRT with MEMs were generally the most reliable methods for partitioning the variation explained by environmental and spatial effects across a wide range of simulated scenarios. The remaining methods tended to underestimate pure spatial effects, because of either underfitting of simulated spatial structures or overestimation of environmental effects compared to spatial effects when jointly estimated. Performing variation partitioning on nine different empirical datasets using these methods yielded contrasting results, especially in the estimation of the spatial fraction of variation. Our results suggest that previously overlooked methods for performing variation partitioning, especially tree‐based ML, offer flexible approaches to analyze site‐by‐species matrices. We provide general guidelines on the usefulness of different models under different ecological and sampling scenarios, for species distribution modeling, community ecology, and macroecology. [ABSTRACT FROM AUTHOR]

Soil organic matter (SOM) decomposition is regulated by a complex set of enzymes. However, the influences of biotic and abiotic factors on spatial variations of soil enzyme activity (EA) within ecosystems remain unresolved. Here, we measured EA at different locations within two afforested lands (coniferous woodland and leguminous shrubland), and simultaneously collected data on soil physico-chemical, vegetation-related, and microbial properties to identify the determinants of EA spatial patterns. The results showed that soil organic C and total N contents were the predominant abiotic factors in regulating absolute EA (EA per unit of oven-dry soil mass) in both afforested lands, while soil pH was the predominant factor in regulating specific EA (EA per unit of microbial biomass (MB)). However, the predominant biotic factors varied with the afforested type: the root biomass and MB were the determinants of EA in the shrubland, whereas the tree distribution, litter and root biomass, and bacterial biomass were the determinants in the woodland. Vegetation-related factors (i.e., litter and root biomass) indirectly influenced soil EA by regulating the soil abiotic factors. Compared with the MB, microbial community composition had a minor impact on EA. The variance of specific EA (EA per unit of MB or SOM) explained by selected factors was much lower than that of absolute EA. In addition, the enzymatic C/N ratio within ecosystems did not follow a general pattern (1:1) observed at a global scale. Our results provide novel experimental insight into ecosystem-level spatial variability of C and N cycling via enzymes, suggesting that soil abiotic factors are more reliable than biotic factors to reflect EA spatial patterns across afforested systems. [ABSTRACT FROM AUTHOR]

Lianas are an important component of subtropical forests, but the mechanisms underlying their spatial distribution patterns have received relatively little attention. Here, we selected 12 most abundant liana species, constituting up to 96.9% of the total liana stems, in a 20‐ha plot in a subtropical evergreen broadleaved forest at 2472–2628 m elevation in SW China. Combining data on topography (convexity, slope, aspect, and elevation) and host trees (density and size) of the plot, we addressed how liana distribution is shaped by host tree properties, topography and spatial autocorrelation by using principal coordinates of neighbor matrices (PCNM) analysis. We found that lianas had an aggregated distribution based on the Ripley's K function. At the community level, PCNM analysis showed that spatial autocorrelation explained 43% variance in liana spatial distribution. Host trees and topography explained 4% and 18% of the variance, but less than 1% variance after taking spatial autocorrelation into consideration. A similar trend was found at the species level. These results indicate that spatial autocorrelation might be the most important factor shaping liana spatial distribution in subtropical forest at high elevation. [ABSTRACT FROM AUTHOR]

The environmental factors that influence tree–grass abundances in tropical savanna and grasslands are not well understood, particularly for woodland–grassland mosaics in humid zones. We studied the effects of abiotic and spatial variables on woody and herbaceous species distributions in a Terai ecosystem of northeastern India. We evaluated the importance of climatic and non-climatic factors that maintain variable tree–grass ratios across the landscape, and also accounted for spatial connectivity and dispersal. We measured species abundances of woody and herbaceous plant species in 134 plots with each 30 m × 30 m in a 519 km2 protected Terai habitat, and derived several climatic and non-climatic environmental factors. We constructed variables based on different models of spatial connectivity among sites, to test their influence on species abundances. We then used redundancy analyses and variation partitioning to quantify the importance of environmental variables and spatial structure on variation in tree–grass abundances. We found that environmental variables including rainfall, fire, water stress, topography and soil nutrients had statistically significant effects on species abundance and tree–grass ratios. Spatial structure was significant, and the best spatial model was an inverse distance-weighted model with linkage extending to 23.5 km, indicating weak dispersal limitation. About 21% of the variation in species abundance was explained by the selected environmental and spatial factors. The results indicate that dynamic plant communities in which spatial–temporal variation in environmental factors may drive stochasticity in species distribution and abundance, thus dominantly influencing on the vegetation mosaic. [ABSTRACT FROM AUTHOR]

To improve our understanding on the temporal aspects of metacommunity structure, we focused on benthic macroinvertebrates collected seasonally (i.e., wet, drying, dry and rewetting seasons) in Dongting Lake, a large subtropical floodplain lake in China. We employed the elements of metacommunity structure (EMS) framework and variation partitioning to examine whether metacommunity structure and its underlying mechanisms vary among seasons with distinct biotic and abiotic features. We found gradual shifts in the main assembly mechanisms throughout the year, from apparent spatial structuring (potentially indicative of mass effects) in the wet season to more environmental filtering dynamics in the dry season. When the degree of connectivity was high in the wet season, the benthic metacommunity was characterized by nested structure associated with clumped species loss, and was shaped mainly by spatial processes. However, quasi-Clemensian structure was assigned to metacommunities in the transitional seasons with intermediate connectivity, during which environmental variables were more important than spatial factors in describing community structure. When the degree of connectivity was low in the dry season, the benthic metacommunity displayed Clementsian structure, which was configured solely by environmental variables. The rapid shifts in metacommunity dynamics between seasons mainly result from the considerable changes in the hydrological conditions of Dongting Lake, as the studied system varies from lacustrine to fluvial phases within a single year. Taken together, our results revealed that taking temporal aspects into account gives a better insight into metacommunity organization, especially when the studied systems embrace remarkable variability in hydrological regimes.

Current analyses of metacommunity data largely focus on global attributes across the entire metacommunity, such as mean alpha, beta, and gamma diversity, as well as the partitioning of compositional variation into single estimates of contributions of space and environmental effects and, more recently, possible contributions of species interactions. However, this view neglects the fact that different species and sites in the landscape can vary widely in how they contribute to these metacommunity‐wide attributes. We argue for a new conceptual framework with matched analytics with the goals of studying the complex and interactive relations between process and pattern in metacommunities that is focused on the variation among species and among sites which we call the 'internal structure' of the metacommunity. To demonstrate how the internal structure could be studied, we create synthetic data using a process‐based colonization–extinction metacommunity model. We then use joint species distribution models to estimate how the contributions of space, environment, and biotic interactions driving metacommunity assembly differ among species and sites. We find that this approach to the internal structure of metacommunities provides useful information about the distinct ways that different species and different sites contribute to metacommunity structure. Although it has limitations, our work points at a more general approach to understand how other possible complexities might affect internal structure and might thus be incorporated into a more cohesive metacommunity theory. [ABSTRACT FROM AUTHOR]

Host-parasite metacommunities are influenced by a myriad of factors, although little is known about which processes affect this relationship at different scales. Here, we tested how local habitat characteristics and host traits explained the parasite metacommunity of a migratory fish in a large Brazilian river floodplain. The parasite metacommunity structure showed a Clementsian pattern, which indicates a more deterministic assembly pattern, in accordance with partial Redundancy Analysis results. Results indicated that species filtering is the predominant mechanism driving community assembly. Patterns were clearer in the dry season of the floodplain. Environmental determinism seems to explain ectoparasite metacommunities in the dry season, in contrast with endoparasites that were more correlated to host traits. Overall, our results indicated that ectoparasitism is an interaction marked by opportunity, whereas endoparasitism is likely related to host features. Thus, we argue that metacommunity structuring of parasites depends on the infection strategy. Our results show that floodplain dynamics are central not only for free-living animal organizations but also for symbiotic interactions. Here, we highlight the importance of understanding the factors influencing the distribution of parasites to predict their transmission, as well as the importance of floodplain dynamics and its hydrological regime on the maintenance of ecological interactions. [ABSTRACT FROM AUTHOR]

[Display omitted] • First results on ant species composition change from Eastern Himalaya. • Species loss, not turnover, forms major part of total composition change. • Species diversity within each functional group decreased towards high elevation. • Functional group composition showed greater diversity and eveness at low elevation than at high elevations Elevational gradients in mountains show rapid changes in environmental conditions across a small geographic extent. This results in habitat specialization in animal communities which results in changes in species composition across space. We explore changes in species and functional group composition of ants using the first ever data on the distribution of ants across an elevational gradient in the Eastern Himalaya. Ants were sampled from 600 to 2400 m elevations at 200 m intervals using Winklers and pitfall traps. The sampling yielded 166 species of ants from 10,560 individuals, which were then classified into functional groups. We used redundancy analysis to test the effects of environmental factors (temperature, leaflitter volume, understory vegetation) and spatial predictors on species as well as functional group composition of communities at different elevations. Our results show that species diversity within all functional groups decreases towards higher elevations. The functional group composition of ant communities shows a gradient from high evenness at low elevations to being dominated by opportunist species at higher elevations. Redundancy analyses shows that most of the variation in species as well as functional group composition is driven by spatially structured environmental variation. This is most likely due to the high correlation between temperature and elevation. In summary, the changes in species as well as functional group composition are likely driven by a gradient in climate across the elevation gradient. [ABSTRACT FROM AUTHOR]