Tree diversity, composition, forest structure and aboveground biomass dynamics after single and repeated fire in a Bornean rain forest

Abstract

Forest fires remain a devastating phenomenon in the tropics that not only affect forest structure and biodiversity, but also contribute significantly to atmospheric CO2. Fire used to be extremely rare in tropical forests, leaving ample time for forests to regenerate to pre-fire conditions. In recent decades, however, tropical forest fires occur more frequently and at larger spatial scales than they used to. We studied forest structure, tree species diversity, tree species composition, and aboveground biomass during the first 7 years since fire in unburned, once burned and twice burned forest of eastern Borneo to determine the rate of recovery of these forests. We paid special attention to changes in the tree species composition during burned forest regeneration because we expect the long-term recovery of aboveground biomass and ecosystem functions in burned forests to largely depend on the successful regeneration of the pre-fire, heavy-wood, species composition. We found that forest structure (canopy openness, leaf area index, herb cover, and stem density) is strongly affected by fire but shows quick recovery. However, species composition shows no or limited recovery and aboveground biomass, which is greatly reduced by fire, continues to be low or decline up to 7 years after fire. Consequently, large amounts of the C released to the atmosphere by fire will not be recaptured by the burned forest ecosystem in the near future. We also observed that repeated fire, with an inter-fire interval of 15 years, does not necessarily lead to a huge deterioration in the regeneration potential of tropical forest. We conclude that burned forests are valuable and should be conserved and that long-term monitoring programs in secondary forests are necessary to determine their recovery rates, especially in relation to aboveground biomass accumulation.

Early recruitment responses to interactions between frequent fires, nutrients, and herbivory in the southern Amazon

“…Similar results were found following fire in India (Saha and Howe 2003). Additional data from Borneo show repeated fires with a return interval of 15 years had similar effects to a single fire event; in both cases biomass and community composition had not recovered after 7 years (Slik et al 2008). …”

Interactions between repeated fire, nutrients, and insect herbivores affect the recovery of diversity in the southern Amazon

“…In addition, fire can reduce species diversity and alter the species composition in favor of root-sprouting species (Saha and Howe 2003). Densities of sapling and adult stems can recover relatively quickly after fire (within 6.5 years in Indonesia), but stand biomass and species evenness are less resilient because of the early dominance of pioneer species (Slik et al 2008). So, although stem density can start to recover within a few years of fire, species composition lags behind, and a loss of diversity or change in species composition can affect forest integrity and function (Lewis 2009).…”

Rainforests at the Beginning of the 21st Century

“…Spatial variability of vegetation and extent of canopy were reduced which resulted in less resource for animals. What's more, new pioneer plant species appeared after fire (Slik et al, 2008 ., 2008). Near the edge of the forests, communities are particularly vulnerable to damage.…”