Canopy recovery and regeneration following drought-induced collapse in a Mediterranean-type eucalypt forest in southwestern Australia

Background/Question/Methods

Globally, drought-induced forest canopy collapse is an increasingly concerning issue.  Little is known about the response of Mediterranean climate ecosystems to disturbances of this type and the role of drought in long-term shifts in forest structure. We investigated the pattern of response in severely affected and minimally affected forest sites in a Mediterranean-type forest in southwestern Australia three, six and 16 months following drought-induced canopy collapse.

Results/Conclusions

The study showed that epicormic resprouting was extensive within severely affected sites, with a much reduced epicormic response on minimally affected sites. A key impact of the collapse was a reduced canopy height and proliferation of new stems formed from coppice regrowth.  Regeneration of Eucalyptus marginata, the dominant overstorey species, was found in higher densities in severely affected forest, predominantly as ground coppice. We have provided evidence for contrasting patterns of recovery over time between forest experiencing different levels of collapse. These finding suggest severely and minimally affected forest are on divergent trajectories.  The pattern of recovery suggests that particular sites may be vulnerable to significant structural shifts with future drought-induced canopy collapse.  Tracking forest health changes in response to such disturbances is critical for predicting future ecosystem change.