Frequent understory fires change the composition of rainforest plant communities, potentially altering the capacity of forests to regenerate, finds a study published in special issue of the journal Philosophical Transactions of the Royal Society B.
The research, which involved a team of researchers from several institutions in the United States and Brazil, assessed the impact of different fire cycles on rainforest plant species. They found that frequent fires — though limited in intensity — substantially affected plant diversity across their field plots. In one plot that was burned five times over a six year period, 29 species disappeared and were replaced by 11 previously unrecorded species typically found along fragmented forest edges.
The findings lend support to the growing body of evidence suggesting that continued fragmentation, coupled with use of fire and increasing incidence of severe drought, could leave the southern Amazon’s forests at increased risk of tipping toward savanna-dominated ecosystems.
“Repeated burns resulted in significant increases in mortality and declines in regeneration, species richness and diversity for small stems (less than 1 cm),” the authors write. “A key result documented here is that although resilience in regeneration capacity is evident after a single fire event, repeated fires substantially inhibit early regeneration of forest species, especially seedling recruitment. Our results imply that a period of frequent burns would eliminate regeneration of several species.”
Rainstorm over the Amazon.
CITATION: Balch JK, Massad TJ, Brando PM, Nepstad DC, Curran LM. 2013 Effects of high-frequency understorey fires on woody plant regeneration in southeastern Amazonian forests. Phil Trans R Soc B 368: 20120157. http://dx.doi.org/10.1098/rstb.2012.0157