Effects of shading and mulch depth on the colonisation of habitat patches by arthropods of rainforest soil and litter


Akihiro Nakamura, Queensland Museum, Cnr Grey and Melbourne Streets, South Brisbane, Queensland 4101, Australia. E-mail: a.nakamura@griffith.edu.au


Abstract.  1. Development of foliage cover and a layer of leaf litter are two factors considered important for the successful recolonisation of soil and litter arthropods during the early stages of rainforest restoration; however, this needs to be tested explicitly.

2. We employed a manipulative field experiment to assess the effects of shading and litter depth on colonisation patterns of soil and litter arthropods in created habitat patches at five replicated sites within pasture adjacent to rainforest remnants on the Maleny plateau of subtropical eastern Australia.

3. Habitat patches were created by adding sterilised mulch at two depths (shallow 3–5 cm, deep 10–15 cm) under three levels of shading (none, 50%, 90%). Responses of arthropods to treatments were analysed at two levels of taxonomic resolution: ‘ordinal-sorted arthropods’ (all arthropods sorted to order/class) and ant species (Hymenoptera: Formicidae).

4. Shading, at both 50% and 90%, encouraged colonisation by arthropods characteristic of rainforest. Colonisation by pasture-associated arthropods declined progressively with increased shading. Effects of mulch depth were significant only for rainforest-associated ant species, which responded positively to shallow mulch within shaded plots.

5. The results confirm that canopy cover is indeed one of the primary attributes influencing colonisation patterns of arthropods in restored vegetation. More widely spaced plantings may facilitate some colonisation by rainforest arthropods. However, in order to suppress invasion by pasture-associated arthropods, it may be necessary to establish a fully closed canopy.