Mendel University in Brno Brno, Jihomoravsky kraj, Czech Republic
Background/Question/Methods:
Selective logging modifies forest structure and composition but the impacts of these changes on the post-logging dynamics and functioning of tropical forests are little understood. The recovery of forests from logging is of importance especially in Southeast Asia, where the relative deforestation rates are the highest among any major tropical regions and selective logging is a widespread harvest technique. In the island of Borneo, despite the key role of logged forests in the human-altered landscape, information on the speed and extent of secondary forest recovery remains scarce.
Over the period 2010–2020, we recorded annual tree growth, mortality, and recruitment in 193 permanent plots (25 x 25 m each) within the Stability of Altered Forest Ecosystems (SAFE) Project in selectively logged tropical rainforest in Malaysian Borneo. Along the logging gradient ranging from heavily, moderately, and lightly logged stands to old-growth forests, we studied the dynamics of tree diversity and composition recovery as well as the impacts of El Niño drought (2015–2016) on tree growth and mortality.
Results/Conclusions:
The results show that increasing the intensity of logging increased the magnitude of the compositional changes, raised the proportion of pioneer species, and decreased the percentage of late-successional species (dipterocarps). In heavily logged forests, there were no signs of recovery in terms of species composition and diversity despite the high species turnover. During 2010–2020, the pioneers grew initially faster than dipterocarps, thus causing faster regrowth of heavily logged plots, however, their growth rate dropped significantly during the El Niño drought (2015–2016) and was similar to or lower than that of dipterocarps since then (i.e., did not recover). The findings indicate that the logging-induced compositional changes may make the forest more vulnerable to future drought events under climate change.
