Nalika Rajapaksha, PhD studentship, University of Central Lancashire (2009-2012)
Summary
An important but largely unidentified aspect of Short Rotation Forestry (SRF) is the quality/quantity of litter, its decomposition and incorporation in the soil environment. This decomposition is primarily dependent on soil faunal diversity and activity. A representative and often important component of the soil fauna is the earthworm community.
Research objectives
The overall aim of this project was to investigate the effect of interacting factors of SRF tree species and soil types on the earthworm community. In addition, the effect of earthworms on litter decomposition, soil carbon and nutrient cycling of these systems was assessed. Specific objectives included:
- To establish a baseline of earthworm diversity at agricultural sites and compare with similarly derived SRF sites.
- To assess and compare the impact of different SRF tree species on earthworm populations.
- To assess the contribution of earthworms to SRF litter decomposition and nutrient recycling.
- To augment Forest Research soil C balance and process models by incorporating earthworm-related data.
- To assist development of a model to predict impacts of SRF on below-ground fauna, thus wider ecosystem functions.
Findings and Recommendations
Field studies demonstrated that a mixed earthworm community utilised non-native species but favoured particular native trees. Earthworm influence on nutrient uptake, tree growth and biomass production varied with SRF species. A one year field experiment showed that rapidly growing Eucalyptus nitens benefited more from earthworm activity than relatively slow growing Betula pendula. Overall, the current work supports the production of SRF, as with only one exception (Castanea sativa), results tended to show that SRF-earthworm interactions were positive. It is perhaps most interesting that non-native E. nitens showed a positive interaction with native British earthworms.
Our Involvement
This PhD project was jointly funded and supervised by Dr Elena Vanguelova at Forest Research and Dr Kevin Butt at the University of Central Lancashire's Earthworm Research Group.
