Assessing the influence of Eisenia andrei on the decomposition of Casuarina equisetifolia litter in vermicompost.

<ns3:p> Background She-oaks (family Casuarinaceae) are pioneer trees that are planted in tropical areas worldwide for different uses, including the restoration of degraded soils. However, these trees produce recalcitrant litter with negative effects on ecosystem recovery. Earthworms can accelerate litter decomposition by modulating the activity of soil microorganisms and other faunal groups involved in organic matter degradation. Methods We conducted an experiment to compare the effect of vermicompost alone or jointly with the activity of the earthworm <ns3:italic>Eisenia andrei</ns3:italic> on the decomposition of <ns3:italic>Casuarina equisetifolia</ns3:italic> litter and on the composition of the mesofaunal community. We prepared 36 microcosms , in each of which a litterbag containing <ns3:italic>C. equisetifolia</ns3:italic> litter was covered with vermicompost. In half of the microcosms, 15 specimens of <ns3:italic>E. andrei</ns3:italic> were added to each box (treatment E), and in the other half, no earthworms were added (treatment VC). The experiment lasted for 40 weeks, and microcosms in both treatments were destructively sampled at 2, 4, 8, 16, 32 and 40 weeks. The treatment effects were evaluated by litter mass loss, variation in litter composition, the number and biomass of earthworms, and the composition of mesofaunal communities. Results After 40 weeks, litter mass loss was greater in treatment E than in treatment VC (55% vs. 45%). Decomposition led to decreases in C and Na concentrations and infrared bands related to carbohydrates and proteins in the litter and increases in elements such as N and P and infrared bands associated with lignin, with no difference between treatments. Earthworm number and biomass decreased throughout the experiment, and earthworm presence did not affect mesofaunal communities, possibly owing to the low palatability of <ns3:italic>C. equisetifolia</ns3:italic> litter. Conclusions Direct application of vermicompost could enhance the decomposition of Casuarinaceae litter in the field. The feasibility of this approach needs to be tested in new experiments. </ns3:p>