Description: Questions The study of naturally discontinuous forest systems could help further our understanding of the relative roles of abiotic factors and spatial connectivity in influencing species turnover and plant metacommunity structure compared to continuous forest formations where local communities are often arbitrarily defined and where ‘mass effects’ and source-sink dynamics tend to confound the roles of dispersal and environment. Here we study a tropical montane landscape where old-growth evergreen forest occurs as patchy formations in a matrix of natural grasslands, to test the influence of environment and connectivity on species turnover and woody plant metacommunity structure . Location The study area consists of the western and southern regions of the Upper Nilgiri Plateau in the Western Ghats of Southern India, a global biodiversity hotspot . Methods We sampled 85 vegetation plots located across a 600 km2 landscape, assembled environmental data, constructed contrasting spatial connectivity models, including models for the effects of topography on structural connectivity, and used RDA-based variation partitioning to assess the relative influence of environment and space on woody plant metacommunity structure . Results Considering several environmental and multi-scale spatial predictors, we could explain half the variation in plant community structure. Environmental and habitat factors such as precipitation, temperature seasonality, elevation, fragment size and landscape context play a dominant role and explain 42% of variation. Spatial predictors based on Euclidean distance performed better than those that accounted for topographical resistance. Spatial predictors accounted for only 9% of the variation in plant metacommunity structure . Conclusion Our results support the species sorting paradigm of metacommunity structure, as abiotic effects and biotic interactions play dominant roles in influencing community structure and species turnover in these old growth forests with a comparatively small influence of spatial connectivity. Effective management of woody species diversity would therefore require conservation of these forests across the range of environmental conditions under which they occur . This article is protected by copyright. All rights reserved.

Description: Questions As biodiversity losses increase due to global change and human-induced habitat destruction, the relationships between plant traits and ecosystem properties can provide a new level of understanding ecosystem complexity. Using a functional response–effect approach, we show that multiple components of the carbon cycle are determined by a few plant traits, which in turn are strongly affected by environmental conditions. Location Salt marshes, northwest Germany. Methods We explored responses of morphological, chemical and biomass-related plant traits to environmental drivers and examined their effects on carbon cycle properties, i.e. above-ground biomass, above-ground net primary productivity and decomposition. The combined analysis between environmental parameters, functional traits and ecosystem properties used structural equation modelling (SEM). Results Important response and effect traits were leaf dry matter content (LDMC) and below-ground dry mass (BDM, responding to groundwater level and salinity) and leaf C:N ratio (responding to inundation frequency). Inundation and salinity led to increased allocation to below-ground biomass and salt stress adaptation in leaves, which translated into increased decomposition rates. Release from these abiotic controls resulted in standing biomass accumulation, which was controlled by LDMC and canopy height as key traits. Conclusions These findings demonstrate the interacting effects of non-consumable environmental factors and soil resources on morphological, chemical and biomass traits, which affected carbon cycle properties. Loss of species from the community has the potential to change the relationships between environment and vegetation-based ecosystem properties and therefore elicit effects on the multifunctionality of the entire and adjacent ecosystems. Studying relationships between plant traits and ecosystem properties can provide new insight into ecosystem complexity. We ask how plant species traits respond to environmental conditions and how key effect traits determine carbon related ecosystem properties in salt marshes of NW-Germany. Our study reveals interacting effects of environmental factors on morphological, chemical and biomass traits and gives recommendations for conservation management.