Species adaptation to both fire and climate change in tropical montane heath: Can Melaleuca uxorum (Myrtaceae) survive?

Abstract

Resprouting following fire is an effective and well utilized strategy for tropical montane heath species which have had a long evolutionary history of intermittent fire disturbance. Research conducted in both burnt and unburnt heath suggests that species richness is related to fire, however actual species presence is dependent upon local burning regimes. Taxa that persist in fire-adapted environments may survive through mechanisms including seed storage in the soil seed bank, resprouting from basal, axillary or epicormic buds, roots/rhizomes or terminal aerial buds and/or through migration of seed. We investigated the montane endemic Melaleuca uxorum’s response to fire to understand local adaptation and persistence to fire in fire prone heath and to understand potential impacts of climate change on montane heath ecosystems. We found that the species resprouts at the stem base, along stems from epicormic buds and from axillary buds. The species forms small colonies which appear to be a mixture of sexual and asexual (clonal) reproduction. We predict that the effects of climate change will conspire against tropical montane heath below 1000 m, and those communities away from maritime influences will be under threat of increasingly reduced population numbers and extent as the dry season cloud base is expected to rise in elevation with anticipated rising temperatures. Furthermore, as evaporation rates increase, such communities are anticipated to lose their local specialized flora and to be replaced by more common unspecialized, widespread species.