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Wetlands are important habitats, often threatened by drainage, eutrophication, and suppression of grazing. In many countries, considerable resources are spent combatting scrub encroachment. Here, we hypothesize that encroachment may benefit biodiversity-especially under eutrophic conditions where asymmetric competition among plants compromises conservation targets. We studied the effects of scrub cover, nutrient levels, and soil moisture on the richness of vascular plants, bryophytes, soil fungi, and microbes in open and overgrown wetlands. We also tested the effect of encroachment, eutrophication, and soil moisture on indicators of conservation value (red-listed species, indicator species, and uniqueness). Plant and bryophyte species richness peaked at low soil fertility, whereas soil fertility promoted soil microbes. Soil fungi responded negatively to increasing soil moisture. Lidar-derived variables reflecting the degree of scrub cover had predominantly positive effects on species richness measures. Conservation value indicators had a negative relationship to soil fertility and a positive to encroachment. For plant indicator species, the negative effect of high nutrient levels was offset by encroachment, supporting our hypothesis of competitive release under shade. The positive effect of soil moisture on indicator species was strong in open habitats only. Nutrient-poor mires and meadows host many rare species and require conservation management by grazing and natural hydrology. On former agricultural lands, where restoration of infertile conditions is unfeasible, we recommend rewilding with opportunities for encroachment toward semi-open willow scrub and swamp forest, with the prospect of high species richness in bryophytes, fungi, and soil microbes and competitive release in the herb layer.

Aims We assessed biodiversity effects of disturbance in meadows and rich fens. We hypothesized that disturbances and their timing affect plant and bryophyte species richness and other indicators of conservation success. More specifically, we expected conservation status to improve with disturbances that mimic natural grazing processes, that is, that extensive year-round grazing with trampling had a more positive effect than intensive summer grazing or mowing. Location Kastbjerg wetlands, Jutland, Denmark. Methods In a three-year field experiment, we applied trampling, season-specific defoliation with biomass removal and burning in a randomized design in nine wetland sites. We recorded species richness and community composition. Bayesian generalized linear mixed-effects models were built with treatment as fixed effect, site as random effect and species richness or species composition as responses. Leaf N and P, and soil moisture were included as covariables. Further, a quadratic discriminant analysis (QDA) was applied to test for discrimination between treatments based on a set of biodiversity indicators. Results Environmental and biotic differences among sites were considerable and significant indicating a considerable effect of historical contingency (local species pool). We found only minor and mostly insignificant effects of disturbance on vegetation. However, a QDA revealed significant differences among treatments based on five indicators for conservation status. Simulated grazing and trampling were generally associated with higher vascular plant richness, bryophyte richness, number of indicator species and stress-tolerant species and decreasing abundance of competitive species. Conclusion We found small, but positive effects of disturbance on biodiversity indicators of wetland vegetation after three years of experimental treatments. Initial site differences explained most variation, indicating strong histo

Most angiosperms rely on animal pollination for reproduction, but the dependence on specific pollinator groups varies greatly between species and localities. Notably, such dependence may be influenced by both floral traits and environmental conditions. Despite its importance, their joint contribution has rarely been studied at the assemblage level. At two elevations on the Caribbean island of Dominica, we measured the floral traits and the relative contributions of insects versus hummingbirds as pollinators of plants in the Rubiaceae family. Pollinator importance was measured as visitation rate (VR) and single visit pollen deposition (SVD), which were combined to assess overall pollinator effectiveness (PE). In the wet and cool Dominican highland, we found that hummingbirds were relatively more frequent and effective pollinators than insects, whereas insects and hummingbirds were equally frequent and effective pollinators at the warmer and less rainy midelevation. Furthermore, floral traits correlated independently of environment with the relative importance of pollinators, hummingbirds being more important in plant species having flowers with long and wide corollas producing higher volumes of dilute nectar. Our findings show that both environmental conditions and floral traits influence whether insects or hummingbirds are the most important pollinators of plants in the Rubiaceae family, highlighting the complexity of plant–pollinator systems.