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The impacts of fires in Amazonian forests are varied – from changes in the forest structure and microclimate to shifts in the taxonomic composition of both fauna and flora. Much less understood is how forest fires affect the distribution of functional traits of the affected forests – i.e. given the elevated mortality of trees in burned forests and the recruitment of pioneer species, is there a shift in plant functional traits? Here we evaluate how forests affected by fire and logging differ from undisturbed ones in 11 morphological and chemical traits of the dominant tree species. We sampled >1,000 individuals distributed across 20 forest plots and calculated the community weighed mean of each of the 11 sampled traits. Surprisingly, we found no significant difference in the community weighed means of the 11 sampled traits. We then compared the community weighed means of the sampled traits between large (>10cm DBH) and small (2-10cm DBH) trees in each forest plot. We found that the community of smaller trees is more functionally different from that of the larger trees in forests affected by both selective logging and forest fires than in undisturbed forests, highlighting a possible future functional shift in forests. This is of great concern as future forests might not perform the same set of functions and, therefore, not deliver the same set of services of current forests, with possible profound impacts on key forests processes such as nutrient cycling and carbon assimilation.

Keywords:

fire; Amazon; degradation; functional traits; logging; forest; climate change; community

Erika Berenguer, Jos Barlow, Yadvinder Malhi, Joice Ferreira

Presentation within symposium:

S-14 Seeing Through the Smoke – fire as a catalyst of Amazonian tipping points

Assessing functional shifts in human-modified Amazonian forests

-Review-