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QUESTIONS: Are community composition and species richness of aquatic macrophytes determined primarily by local (habitat heterogeneity and water quality) or regional (climate) patterns at regional scale? Do two macrophyte functional groups (i.e. emergent and submerged macrophytes) respond similarly to local and regional patterns? Are lake macrophytes and explanatory variables geographically structured? LOCATION: The US state of Minnesota. METHODS: The community composition and species richness of aquatic flora was studied using presence–absence data in 454 lakes, covering the entire US state of Minnesota. In addition, community composition and species richness of emergent and submerged macrophytes was investigated separately. Variation partitioning based on partial redundancy analysis and partial linear regression was used to study the relative roles of water quality, habitat heterogeneity, climate and sampling effort in explaining community composition and species richness of lake macrophytes, respectively. RESULTS: Macrophyte community composition and species richness (all taxa and two functional groups) were explained by water quality and climate. Alkalinity and total phosphorus were water quality variables that most affected community composition of aquatic flora, and macrophyte species richness decreased with increasing concentrations of these two variables. Maximum temperature of the warmest month and mean annual temperature most affected plant community composition, whereas species richness had a negative relationship with minimum temperature of the coldest month. Most significant explanatory variables (e.g. alkalinity, total phosphorus and temperature) were geographically structured, showing a latitudinal change. CONCLUSIONS: Community composition and species richness of macrophytes were congruently influenced by regional (climate) and local patterns (water quality) at regional scale. Community composition and species richness of helophytes and submerged macrophytes were equally explained by environmental gradients. The latitudinal change in these most significant environmental variables was related to calcareous soils and intensive agriculture, which were situated in the southern part of the state. Macrophyte species richness showed a reverse latitudinal gradient, which was likely due to high nutrient concentrations in southern latitude lakes. Water quality primarily filters species from the regional species pool, allowing only species tolerating high nutrient concentrations, e.g. invasive plants, to survive at southern latitudes.

Functional homogenisation occurs across many areas and organism groups, thereby seriously affecting biodiversity loss and ecosystem functioning. In this study, we examined how functional features of aquatic macrophytes have changed during a 70-year period at community and species levels in a boreal lake district. At the community level, we examined if aquatic macrophyte communities showed different spatial patterns in functional composition and functional richness in relation to main environmental drivers between the time periods. We also observed each species in functional space to assess if species with certain sets of traits have become more common or rare in the 70-year study period. We found changes in the relationship between functional community composition and the environment. The aquatic macrophyte communities showed different patterns in functional composition between the two time periods, and the main environmental drivers for these changes were partly different. Temporal changes in functional richness were only partially linked to concomitant changes in the environment, while stable factors were more important. Species’ functional traits were not associated with commonness or rarity patterns. Our findings revealed that functional homogenisation has not occurred across these boreal lakes, ranging from small oligotrophic forest lakes to larger lakes affected by human impacts.

Aim Geodiversity underpins biodiversity, but the contribution of specific geofeatures or landforms has rarely been explored. In this study, we use multiple vascular plant species diversity measures on alpha, beta and gamma levels to explore the linkage between biodiversity and co‐located landforms (e.g. gullies, dunes and lake shores). We hypothesize that biodiversity will be positively related to geodiversity, which is founded on distinct landforms. Additionally, we propose that different landforms will sustain different amounts of biodiversity and that high alpha and gamma diversity values are related to landform‐driven moisture availability whereas high beta diversity relates especially to landform‐specific microtopographic variation. Location Rokua UNESCO Global Geopark area, Finland. Taxon Vascular plants. Methods We compare vascular plant species richness measures, Shannon's and Simpson's diversity indices, rarity‐weighted richness and local contribution to beta diversity at altogether three levels of biodiversity (alpha, beta and gamma) for different landforms. Landform information is compiled from aerial photos, spatial data layers and targeted field surveys. We compare results to control habitat (i.e. sites without any distinct landforms) within the study area. Results Vascular plant diversity was higher on landforms than in control habitat. There was also notable variation between species diversity of different landforms. Moisture‐rich gullies and river shores were especially diverse at all three levels, whereas aapa mires hosted most unique species composition (highest beta diversity). Beta diversity patterns were rather comparable with alpha and gamma diversity patterns, which contradict our hypothesis. Main conclusions This study quantitatively established a strong connection between terrestrial plant communities and multiple landforms. Our results highlighted the landform‐controlled variation in soil moisture, microclimate and microtopography in enhancing plant species diversity. Based on the results, we promote the inclusion of landform‐based geodiversity information in conservation management and in further biogeographical studies.

Aim: Spatial extent is inherently related to the potential roles of the main mechanisms structuring metacommunities. We examined the effects of varying spatial extent (ecological province, region and subregion) on the environmental and spatial components of variation in lake macrophyte communities. We also studied these effects separately for three macrophyte functional groups. Location: The US state of Minnesota. Methods: We examined average and heterogeneity differences in macrophyte community composition and environmental variation among the subregions of Minnesota using canonical analysis of principal coordinates (CAP) and homogeneity of multivariate dispersion (PERMDISP), respectively. We further used partial redundancy analysis (pRDA) to decompose variation in macrophyte community composition between environmental variables and spatial location at each spatial extent and geographical region. Spatial variables were derived using principal coordinates of neighbour matrices (PCNM) analysis. Results: CAP and PERMDISP analyses showed that the subregions differed both in average community composition and in the heterogeneity of community composition for all macrophyte taxa, for emergent and submerged macrophytes, but not for non-rooted macrophytes. We did not, however, find significant differences in overall environmental heterogeneity among the subregions. Variation partitioning using pRDAs showed that species sorting is more important than spatial processes for macrophytes, although these patterns were relatively weak. There was, however, much regional specificity, with the environmental and spatial fractions of community composition varying widely at different spatial extents, among different geographical regions and among functional groups. Contrary to our initial expectations, we did not find increasing spatial structuring and decreasing environmental control with increasing spatial extent. Main conclusions: Our findings indicate that, in macrophyte metacommunities, the relative contribution of spatial processes and environmental control varies rather unpredictably with spatial extent and geographical region. Our findings are thus of importance in advancing metacommunity ecology by showing that drawing wide-ranging conclusions based on a single spatial extent or a single geographical region may be unwise.

Aim Conserving freshwater biodiversity in a rapidly changing world requires updated planning schemes and research efforts. Geodiversity – the diversity of Earth surface forms, materials and processes – and biodiversity are interlinked at a fundamental level. This relationship is being considered in a growing number of studies, yet research from freshwater environments is scarce. We used geodiversity (rock‐type, soil‐type and geomorphological richness), local and climatic variables to explore whether geodiversity can be used as a surrogate for aquatic plant species richness in lakes and rivers. Location Finland. Taxon Aquatic plants. Methods We compared geodiversity variables (measured within 1‐km2 grid cells) to well‐studied local (e.g. area, alkalinity) and climate (e.g. growing degree‐days) variables, and examined the patterns between habitat types (lakes and rivers) and among all taxa and major functional groups (helophytes and hydrophytes). We modelled lake (n = 145) and river (n = 146) plant species richness with generalized linear models, and further partitioned variation to measure the independent and shared contributions of the geodiversity, climate and local environmental variable groups. As a complementary analysis, and to identify single important variables explaining variation in aquatic plant species richness, we utilized boosted regression trees. Results We found a positive relationship between aquatic plant species richness and catchment geodiversity variation with recurring patterns across two different freshwater habitat types and two aquatic plant functional groups. Higher variation in geodiversity (measured at landscape scale) supported higher freshwater biodiversity (measured at the local scale) of lakes and rivers. Main conclusions Geodiversity can be a useful addition to biodiversity modelling, and it should be considered in conservation schemes and monitoring efforts, further supporting the principle of conserving nature's stage. Yet, differences between habitats and functional groups suggest that more habitat‐specific approaches and multiple biodiversity measures should be considered. Our study is an important signpost guiding further studies on the biodiversity–geodiversity relationship in freshwater ecosystems.

A multi-faceted approach is needed to better understand how the beta diversity of aquatic assemblages responds to ecological gradients. Using distance-based RDA and variance partitioning, we explored the different components of total beta diversity (replacement and richness difference) based on taxonomic, functional, and phylogenetic data of aquatic macrophytes along environmental and spatial gradients across 49 tropical floodplain lakes in the Pantanal of Mato Grosso in the dry season. We found that taxonomic beta diversity was driven by species replacement, while functional beta diversity was mostly contributed by richness difference and phylogenetic beta diversity was equally contributed by both components. Taxonomic and functional beta diversities were driven by environmental variables, connectivity variables, and directional spatial processes. Phylogenetic beta diversity was mainly affected by the connectivity between the sites and their distance from the river. The relationship between environmental variables and beta diversity indicates that a selection of species with similar functional and phylogenetic characteristics co-occurs at a site. The low connectivity between sites and the increased distance between the lakes and the river suggested dispersal limitation, which was due to the absence of directional exchange of species between lakes. Our findings provided new insights into the beta diversity patterns of aquatic macrophytes and their underlying causes in tropical floodplains.

We investigated whether environmental filtering or dispersal-related factors mostly drive helophyte and hydrophyte species richness and community composition in 93 lakes situated in Baikal Siberia. Using partial linear regression and partial redundancy analysis, we studied (1) what are the relative roles of environmental variables, dispersal variables, spatial processes and region identity (i.e., river basins) in explaining variation in the species richness and species composition of helophytes and hydrophytes across 93 Siberian lakes, and (2) what are the differences in the most important explanatory variables driving community variation in helophytes versus hydrophytes? We found that, for both species richness and species composition, environmental variables clearly explained most variation for both plant groups, followed by region identity and dispersal-related variables. Spatial variables were significant only for the species composition of hydrophytes. Nutrient-salinity index, a proxy for habitat trophic-salinity status, was by far the most significant environmental determinant of helophytes and hydrophytes. Our results indicate that environmental factors explained the most variation in both species richness and species composition of helophytes and hydrophytes. Nevertheless, dispersal-related variables (i.e. spatial and dispersal) were also influential but less important than environmental factors. Furthermore, the dispersal-related variables were more important for hydrophytes than for helophytes. Most brackish permanent lakes were mostly located in the steppe biomes of southern Transbaikalia. This characteristic along with the oldest age, the largest distances to both river and settlements and the lowest temperatures in the study region distinguished them from freshwater, drained and more nutrient-rich floodplain lakes.

Species distributions are structured by regional and local determinants, which operate at multiple spatial and temporal scales. The purpose of our work was to distinguish the relative roles of local variables, climate, geographical location and post glaciation condition (i.e., delineation between supra- and subaquatic lakes during the post-glacial Ancylus Lake) in explaining variation in macrophyte community composition of all taxa, helophytes and hydrophytes. In addition, we investigated how these four explanatory variable groups affected macrophyte strategy groups based on Grime’s classification. Using partial linear regression and variation partitioning, we found that macrophyte communities are primarily filtered by local determinants together with regional characteristics at the studied spatial scale. We further evidenced that post glaciation condition indirectly influenced on local water quality variables, which in turn directly contributed to the macrophyte communities. We thus suggest that regional determinants interact with local-scale abiotic factors in explaining macrophyte community patterns and examining only regional or local factors is not sufficient for understanding how aquatic macrophyte communities are structured locally and regionally.

Changes in natural land cover have been pronounced in the last 12,000 years, and land use has intensified in the last century owing to anthropogenic pressures on landscapes. This trend has led to concomitant changes in the abiotic templates and biotic communities of different ecosystems embedded in a landscape. Deciphering the role of land use is key to understand ecological change in boreal landscapes. These landscapes are characterized by large numbers of lakes that have been affected by various anthropogenic factors, of which land use has considerable direct and indirect effects on lakes. In this review, we focus on land use impacts on boreal lakes in a historical perspective. We will consider lake features related to abiotic conditions, biological communities and ecosystem services, and provide potential solutions for planning lake management and conservation in a landscape setting. More specifically, we propose a novel way to characterize lake abiotic, biotic and ecosystem service features by applying the alpha, beta and gamma concept used widely in ecological research. Finally, we highlight situations where this approach could be a valuable addition to existing means to identify lakes that should be reserved for ecosystem services (‘lake‐sharing’) and those that are vital for protecting aquatic biodiversity (‘lake‐sparing’). Here, we reviewed how land use may have affected the abiotic conditions, biodiversity and ecosystem services of boreal lakes. We propose a new approach to characterize these three features using the alpha, beta and gamma components widely used in ecology.