Litter decomposition and microbial communities alters depending on litter type and overstory species in revegetated agricultural land

摘要

Acacia and Eucalyptus species are commonly used for revegetation in Australia and other parts of the world, yet little is known regarding how their litter might differentially impact decomposition rates and extracellular enzyme activities. To investigate this, a litter decomposition experiment was established using a reciprocal design (litter type x dominant overstory genus) in Acacia and Eucalyptus revegetation shelterbelts on a common soil to assess rates of decomposition and C degradation associated with differences in enzyme activities and microbial communities. Litter bags with two mesh sizes were used to either exclude (<2 mm) or allow access (>2 mm) by soil macrofauna. Bags were filled with either Eucalyptus, Acacia or an equal mix of Acacia and Eucalyptus litter. Decomposition, enzyme activities and bacterial and fungal community profiles were determined following recovery of surface-placed bags at 40, 96, 187, 307 days and 395 days and a buried control at day 395. Our findings did not support that mixed litter and litter under the same overstory genus would decay at a faster rate than that under a different overstory, in our study litter decomposition was greatest in Acacia litter irrespective of overstory genus. The abundance and structure of bacterial and fungal communities were assessed by terminal restriction fragment length polymorphism (T-RFLP) of 16S rRNA genes and quantified by qPCR. We were able to demonstrate that distinct fungal and bacterial communities occupied each litter type and these also differed between dominant overstory genus. However, we still lack a predictive framework for understanding more generally the impact of different plant species mixes on revegetation outcomes, including rates of return of contribution to ecosystem function.