Plant trait composition as an indicator for the ecological memory of rehabilitated floodplains

Maintaining ecosystem functioning under global change requires resilient ecosystems to absorb disturbances, reorganize and maintain the adaptive capacity. Maintaining resilience is therefore a common objective for ecosystem management, but how this objective may be achieved remains largely unclear. The concept of ecological memory provides a perspective on how the adaptive capacity of ecosystems can be enhanced through management. It specifies how ecological processes in space and time assist in the reorganization of communities after disturbances. We present a trait-based approach that links environmental variables at site and patch level to plant traits. With a generalized linear mixed-effects model we test how environmental variation in management and floodplain dynamics, within and between sites, relates to plant traits that are considered relevant for ecological memory. The results show different mechanisms that intervene in ecological memory. Grazing enhances recruitment opportunities, both for internal reorganization and for colonization between sites. Dense vegetation structure selects for species survival via resprouting after disturbance and competitive species. Hydrodynamics interact with seed dispersal mechanisms and seed persistence. We show that at different spatial levels, plant trait composition can act as an indicator of ecological processes contributing to the ecological memory of a floodplain ecosystem. For ecosystem management to maintain and use as much of this memory as possible it should incorporate management measures at various levels of scale to enhance ecosystem resilience.