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Questions Is macrophyte beta diversity in temporary ponds generated mainly by turnover along a latitudinal gradient? Is macrophyte beta diversity more strongly correlated with differences in local environmental conditions and climate than geographical distances? Are hydrophytes and helophytes correlated with distinct environmental drivers? Location Southern Brazilian Coastal Plain. Methods Macrophyte communities were studied in 24 ponds distributed along a latitudinal gradient. Beta diversity was calculated with the Sorensen dissimilarity index (and further partitioned into turnover and nestedness components). We assessed the individual correspondence of macrophyte beta diversity with local (water quality and habitat structure; after pre‐selection procedures on each explanatory matrix) and climatic environmental drivers, as well as with the geographical distances, through Mantel correlation tests. Partial Mantel tests were carried out to assess the correspondence of beta diversity with the climatic drivers and geographical distances while controlling for the effect of each explanatory matrix. Separate assessments were carried out for subsets of hydrophytes and helophytes. Results Macrophyte beta diversity was mainly generated by turnover. Mantel tests detected significant correlations of macrophyte beta diversity with climatic rather than with local environmental drivers. Partial Mantel tests detected significant relationships only between macrophyte beta diversity and climate (rather than geographical distances). Helophytes were more strongly correlated with climate than hydrophytes, and geographical distances were significantly correlated to hydrophyte beta diversity only. Conclusions Our results indicate that macrophyte communities in southern Brazilian coastal temporary ponds are mainly assembled by species sorting processes, although the contribution of each assembly mechanism differed between functional groups (spatial processes were more important for hydrophytes than helophytes). The distinct relationships of hydrophytes and helophytes with climate suggest different sensitivity of each functional group to environmental changes in temporary ponds. We investigated the assembly mechanisms structuring macrophyte communities in temporary ponds. We correlated macrophyte beta diversity (and its turnover and nestedness components) with water quality, habitat structure, and climatic drivers (proxies of species sorting), and with geographical distances among ponds (proxies of spatial processes). Species sorting predominated in assembling macrophyte communities, although spatial processes influenced hydrophytes more strongly than helophytes.

Vascular plants that presently grow and often dominate wetland habitats are mostly derived from ancestors adapted to dry terrestrial environments. We hypothesize that recently evolved wetland lineages dominate more challenging or novel wetland environments, whereas older lineages tend to dominate widespread and more stable wetland types, likely due to greater dispersal capabilities, as wetland habitats are geologically transient. The regional wetland flora of southern Africa is investigated by listing all species that are flood‐tolerant without specific adaptations, mesophytic, helophytic, and aquatic. The age in which species moved from one state to another was calculated by projecting the traits onto the phylogenetic tree of all vascular plants. Diversification rates were calculated for eight different plant orders in order to determine and compare levels of preadaptation. The occurrence of wetland plants of different age groups (the period in geological history in which they transitioned from the flood‐tolerant stage to the mesophytic stage) was mapped across the different current wetland habitats found in the region and correlated to environmental variables by means of a redundancy analysis. The orders Alismatales and Poales have the most extant wetland species and have been proven to transition to states of wetland adaptation the most frequently in the course of their evolution. Lineages in the monocots generally tend to be more preadapted towards wetland environments than dicots. Some wetland habitats in southern Africa are currently occupied by species that have only recently transitioned towards wetland adaptations, such as saline pans. Wetlands in savanna and grassland vegetation are dominated by species that have spent a much larger part of their evolutionary history in wetland environments. This study emphasizes the contribution to the wetland flora from a regional perspective, but it should be noted that many of the transitions would have taken place outside of the actual region of study. Wetlands are dominated by different lineages of vascular plants in different habitats.

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.

We investigated how land use at multiple scales affects functional macrophytes groups and ecological status index in the boreal region. We employed a variance partitioning analysis to quantify the relative role of lake characteristics, multiple-scaled land use (catchment, buffer zones of 100, 300 and 500 m), and space in explaining the composition and richness of functional macrophyte groups (emergent and submerged macrophytes and hydrophytes) and ecological status of macrophytes in 110 Finnish lakes. Partial redundancy analysis (community composition) and partial linear regression (richness and status index) revealed that macrophyte community composition, richness, and status index were mostly explained by the pure effect of lake characteristics, which dominated over space for most macrophyte variables. Land use adjacent to shoreline had a higher effect on emergent macrophytes and status index compared to the land use of the whole catchment. Our findings suggest that emergent macrophytes can indicate changes in water quality and hydro-morphology originated from the close vicinity of the littoral zone. Ecological quality assessment based on emergent macrophytes only is probably not sufficient, but including emergent species in the assessments is recommended, especially in the species-poor boreal region.

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.

Aim Aquatic-terrestrial ecotones are vulnerable to climate change, and degradation of the emergent aquatic macrophyte zone would have severe ecological consequences for freshwater, wetland and terrestrial ecosystems. Our aim was to uncover future changes in boreal emergent aquatic macrophyte zones by modelling the occurrence and percentage cover of emergent aquatic vegetation under different climate scenarios in Finland by the 2050s. Location Finland, northern Europe. Methods Data derived from different GIS sources were used to estimate future emergent aquatic macrophyte distributions in all catchments in Finland (848 in total). We used generalized additive models (GAM) with a full stepwise selection algorithm and Akaike information criterion to explore the main environmental determinates (climate and geomorphology) of emergent aquatic macrophyte distributions, which were derived from the national subclass of CORINE land-cover classification. The accuracy of the distribution models (GAMs) was cross-validated, using percentage of explained deviance and the area under the curve derived from the receiver-operating characteristic plots. Results Our results indicated that emergent aquatic macrophytes will expand their distributions northwards from the current catchments and percentage cover will increase in all of the catchments in all climate scenarios. Growing degree-days was the primary determinant affecting distributions of emergent aquatic macrophytes. Inclusion of geomorphological variables clearly improved model performance in both model exercises compared with pure climate variables. Main conclusions Emergent aquatic macrophyte distributions will expand due to climate change. Many emergent aquatic plant species have already expanded their distributions during the past decades, and this process will continue in the years 2051-80. Emergent aquatic macrophytes pose an increasing overgrowth risk for sensitive macrophyte species in boreal freshwater ecosystems, which should be acknowledged in management and conservation actions. We conclude that predictions based on GIS data can provide useful ‘first-filter' estimates of changes in aquatic-terrestrial ecotones.

Upland rivers across Europe still exhibit undisturbed conditions and represent a treasure that we cannot afford to lose. We hypothesize that the combination of pristine and modified conditions could demonstrate biological responses along the stressor gradients. Thus, the response of aquatic macrophyte communities to anthropogenic stressors along upland rivers in Bulgaria was studied. Six stressors were selected out of 36 parameters grouped into hydromorphological, chemical variables and combined drivers (catchment land use). The stressors strongly affected species richness on the basis of biological type (bryophytes vs. vascular plants) and ecomorphological type (hydrophytes vs. helophytes). Hydrological alteration expressed by the change of the river’s base flow and altered riparian habitats has led to a suppression of bryophytes and a dominance of riverbank plant communities. Seventy-five percent of mountain sites were lacking bryophytes, and the vegetation at semi-mountainous sites was dominated by vascular plants. It can be concluded that hydropeaking, organic and inorganic pollution, and discontinuous urban structures caused important modifications in the aquatic macrophyte assemblages. Macrophyte abundance and the biological and ecomorphological type of aquatic macrophytes reflect multi-stressor effects in upland rivers.

Redensification of the housing stock is also creating challenges for the drainage of wastewater and rainwater in existing sewer systems, particularly in growing cities. One alternative here is the evaporation of rainwater, which reduces hydraulic loads on sewers. Rainwater evapotranspiration using helophyte mats on building roofs is a possible approach. Helophytes are able to transpire considerably more rainwater than extensively planted green roofs. Other than conventional green roofs helophyte mats in the form of wetland roofs require a permanent water supply on a daily basis. Greywater application can be an additional advantage in terms of nutrient supply of the wetland roof after being treated microbiologically within the plant carrier mat. The treatment of greywater using a helophyte-planted roof can help to meet the water and nutrient requirements of the helophytes even during rain-free periods. However, it must be ensured that the root mat treats the greywater to a sufficient extent. It was shown under practical conditions that a 0.1 m-thick helophyte mat is suitable for treating typical domestic greywater at loads of up to 15 L m−2 d−1.

Based on the study of three zones (free flow, estuarine and reservoir) transition sections tributaries of the plain reservoir, various aspects of the biology and ecology of three representatives of the genus Sparganium were examined. It was demonstrated that S. emersum , thanks to its high ecological plasticity, forms stands in all transitional zones of tributaries. Sparganium erectum participates in the formation of the vegetation cover in the estuarine and littoral zones of the reservoir, while S. microcarpum is not found in the littoral zone of the reservoir. It was shown that the latter two taxa are particularly sensitive to changes in the water level regime, which affects their ability to maintain their positions in phytocenoses. Using Sparganium as an example, it was established that the influence of the water level in the zone of river water discharge has an impact on the timing of reaching maximum biomass values, both in the free-flowing river zones and in their estuarine areas. It was found that the populations of S. emersum that achieve the greatest phytomass grow in the mouth areas of the reservoir tributaries, S. microcarpum , in the free flow zone of rivers, and S. erectum , in the mouth areas of rivers and in the littoral zone of the reservoir.

Studies of community assembly focus on finding rules that predict which species can become member of a plant community. Within a community, species can be categorized in two ways: functional groups classify species according to their functional traits, whereas generalized guilds group species based on their (co-)occurrence, spatial distribution and abundance patterns. This study searches for community assembly rules by testing for coherence among functional groups and generalized guilds, as well as for correlations between the individual functional traits and assembly features, in two wetland plant communities in South Africa. The classifications of functional groups and generalized guilds were not consistent. However, rhizome internode length was related to fine-scale spatial pattern, suggesting that in systems dominated by clonal species (including wetlands, where recruitment sites are strongly limited) community assembly may be strongly linked to colonization ability. Functional groups do not predict guilds in wetland plant communities, precluding their use as the basis for assembly rules. However, an explicit consideration of clonal strategies and their effect on species' spatial patterns appears to be important for understanding community assembly in systems dominated by clonal plants.