Ecological restoration using litter transplants increases decomposition
rates and alters detritivore communities
Abstract
Habitat degradation and the associated reductions in ecosystem function
can be reversed by reintroducing or ‘rewilding’ keystone species.
Rewilding projects have historically targeted restoration of processes
such as grazing regimes or top-down predation effects. Few projects have
focussed on restoring decomposition efficiency, despite the pivotal role
decomposition plays in global carbon sequestration and nutrient cycling.
Here, we tested whether rewilding entire communities of detritivorous
invertebrates and microbes can improve litter decomposition efficiency
and restore detritivore communities during ecological restoration.
Rewilding was conducted by transplanting leaf litter and soil, including
associated invertebrate and microbial communities from species-rich
remnant sites into species-poor, and geographically isolated,
revegetated farmland sites. We sampled pre- and post-rewilding
communities, comparing remnant, rewilded revegetation, and control
revegetation sites for litter decomposition and the abundance and
diversity of detritivorous invertebrates and microbes. We also
quantified the effect of detritivores on the rate of litter
decomposition using piecewise Structural Equation Modelling.
Decomposition was significantly faster in rewilding sites than both
control and remnant areas and was largely driven by a greater abundance
of invertebrate detritivores. Similarly, the abundance of invertebrate
detritivores in rewilding revegetation sites exceeded the level of
remnant communities, whereas there was little difference between control
and remnant sites. In contrast, saprotrophic fungi contributed little to
decomposition. Areas selected for agriculture were likely more
productive than remnant sites, suggesting that restoration sites have
the capacity for higher decomposition rates and more abundant
detritivore communities than target remnant sites. Importantly, our
findings suggest that the novel and relatively simple act of
transplanting leaf litter can increase functional efficiency during
restoration and alter community composition. Our methods may prove
important across a range of contexts where other restoration methods
have failed to restore ecosystem processes to pre-degradation levels.