Depletion of regenerative bud resources during cyclic drought: What are the implications for fire management?

Abstract

Resprouting is a common regenerative strategy in plant taxa that occurs in fire and drought-prone environments. When plants are forced to use bud resources in quick succession as a result of repeated disturbances, recovery vigour may be diminished. The loss of bud resources through the combined effect of successive fire and drought is likely to be more damaging for plant survival and persistence than one or other disturbance on its own. In this study, we examine the resprouting response of seven trees and two shrubs after fire and drought in woodland communities in the New England and Bioregion of New South Wales. We also investigate whether there is a cumulative impact on plant vitality as a result of the combined disturbances of fire followed by drought. Preliminary results suggest that resprouting after drought occurs from buds located on the same morphological parts of tree and shrub species as after fire, although the response reflects the intensity of impact. Mortality in nine species affected by drought was similar to that in plants affected by both fire and drought. Since a drought between successive fires has the potential to deplete bud resources and debilitate plants, drought should be taken into account when determining fire regimes, and a severe drought between two fires should be considered in a similar way to an unplanned burn. Failure to do so may lead to reduced vigour and excessive mortality in resprouting species after planned fire.