Digging by vertebrates as an activity promoting the development of water-repellent patches in sub-surface soil

Dry sclerophyll woodlands in south-western Australia are refugia for remnant populations of woylies Bettongia penicillata. These marsupials create holes as they forage for the fruiting bodies of hypogeous fungi. The effect of these holes on the water-repellent woodland soils was evaluated using simulated diggings. Water repellency was significantly higher in surface than in subsurface soils, although parches of moderately water-repellent sub-soils did occur. In situ assessments of simulated diggings that were allowed to decay showed a five-fold increase in water repellency in sub-surface soil once they had become filled-in. Buried organic material was found in many decayed diggings that were severely wafer-repellent, and very severe water repellency occurred where masses of fungal hyphae were present. This suggests that vertebrate diggings in which surface litter and organic debris become trapped can provide a site for the development of sub-surface water repellency. (C) 2000 Academic Press.