Plant traits relate to whole‐community litter quality and decomposition following land use change

Abstract

Summary Given the speed and extent of changes in vegetation as a result of human activity, there is a need to investigate ways in which individual species’ impacts on ecosystem processes can be generalized and scaled‐up to the community level. We focus on linking community functional parameters (mean of the traits of the plants in the community, weighted using four different methods) with litter chemistry and decomposition, in a chronosequence of currently managed and abandoned semi‐natural grasslands in southern Sweden. Changes in plant community composition with age since abandonment were reflected in community functional parameters: as expected, aggregated specific leaf area (SLA) declined, and aggregated leaf dry matter content (LDMC) and leaf carbon : nitrogen ratio (C : N) increased with plot age. Several litter chemistry indices were closely linked with plant traits at the community level; in particular, community aggregated LDMC was correlated with the lignin and fibre content of the community litter. Aggregated LDMC stood out as the trait most closely linked to community litter decomposition. This relationship was consistent across all three incubation periods (by which time up to c. 70% mass loss had occurred) and as strong as that between the best single chemical index of litter quality (lignin : N ratio) and litter mass loss. Mass loss of whole community litter, incubated in its plot of origin, was related to mass loss of the same litter incubated under standard conditions, but not to decomposition of a standard substrate, indicating dominant substrate quality control over decomposition. This study demonstrates the potential of the traits of living plants as a tool to link changes in species composition with ecosystem processes at the community level.