The decline of Australian mammals: Implications for ecosystem function in Phytophthora affected communities

Abstract. Phytophthora cinnamomi has major effects on floristics and structure in native sclerophyll vegetation in Australia and recent studies have shown that P. cinnamomi can also alter the diversity and abundance of small mammals within affected areas. Overseas research has found that vertebrate fauna can influence a number of key ecosystem processes. This paper reviews some of the evidence for similar effects in Australia and examines the implications of a decline in vertebrate fauna for ecosystem function in Phytophthora affected communities. The effects of digging on ecosystem function is demonstrated by studies of the Woylie (Bettongia penicillata) in Australia. Woylies forage for the underground fruiting bodies of ectomycorrhizal fungi and create up to 110 diggings per night. At this rate individual Woylies can disturb in excess of 5.5 tonnes of soil annually. Experiments using simulated woylie diggings show that they reduce soil water repellency, affect the availability of nutrients and alter the particle size distribution of the soil. These studies also show that a decline in their population results in a loss of this digging activity and suggests any large scale disturbance that alters the guild of fauna within an ecosystem may alter functional processes as well. In experiments currently being initiated, the changes in functional processes due to altered fauna guilds will be examined in Phytophthora affected communities in southern Australia. It will provide a detailed examination of soil disturbance (biopedturbation) by a suite of digging species as they forage for the fruiting bodies of underground fungi (mycophagy). These fungi (ectomycorrhizae) play vital role in the supply of nutrients to plants. However, there is little information on the impact of Phytophthora on the production of fruiting bodies, or the effects on vertebrate foraging and soil disturbance. Nectar resources and vertebrate pollination will also be measured