Ecology and conservation of remnant Melaleuca ericifolia stands in the Tamar Valley, Tasmania

Abstract

Floristic and structural variation in Melaleuca ericifolia-dominated vegetation in the Tamar Valley, Tasmania, appears to be closely related to two major environmental gradients-drainage and soil fertility. Species-poor, dense and tall estuarine paperbark forest occupies fertile alluvial ground with gentle slopes close to the estuary. Sedgy paperbark forest occupies more sloping, but still relatively fertile ground. Coastal paperbark scrub occupies poorly drained ground of relatively low fertility. Grassy paperbark forest occurs in areas of better drainage and relatively high fertility. Size-class distribution data from 40 stands indicate that the trees in M. ericifolia forests and scrubs in large areas of continuous natural vegetation tend to be even-aged, indicating regeneration after burning, while those in more fragmented vegetation tend to have a variety of size classes, suggesting more continuous regeneration events. Stands close to sources of exotic disseminules have significantly higher exotic species cover than those more remote, with exotic cover also influenced by N and available P in the topsoil. The Native Point Nature Reserve and Asbestos Range National Park are two of the few places in the region where M. ericifolia forest and scrub can be expected to survive in good condition. However, regeneration of M. ericifolia occurs even in fragmented stands with high exotic cover in the understorey.