Factors influencing the integrity of remnant bushland in subhumid Tasmania

The relationships between remnant integrity and size, age, shape, environment and disturbance are not well-established. One hundred of the remnants in relatively good condition ranging in size from 5 to 200 ha in the drier parts of Tasmania were sampled and the relationships between independent variables and the dependent variables of remnant native species richness, remnant exotic species richness, the ratio between the two, native species cover, exotic species over, and the ratio of exotic/native cover were investigated. Age, shape and proximity of remnants had few or no effects on the dependent variables. Size appeared to affect the condition variables only through habitat heterogeneity. The nature of the surrounding vegetation and fire and grazing management were the critical independent variables. However, the different aspects of integrity had different relationships with these variables.