BIG TREES, BIG FALL: LARGE-DIAMETER TREES AND THE FATE OF CARBON STOCKS IN ATLANTIC FOREST REMNANTS

Large trees ( i.e . ≥ 50 cm diameter) are known for being more susceptible to stress, and its decline in fragmented forests have been reported as an important cause of carbon loss associated with forest degradation. In this paper, we investigate along edge-interior gradients (0-250 m) the distribution, biomass and health indicators (trunk and branch breaks, partial crown death, fungi infection, termites and liana infestation) of live and standing dead Large Trees (LTs; diameter ≥ 50 cm), in five seasonal Atlantic Forests (34 to 690 ha) of northern Parana state, Brazil. We sampled 118 live LTs in the five forest fragments, where aboveground biomass (AGB) ranged from 22 to 78 Mg/ha, living tree abundance ranged from 8 to 25.6 trees/ha, and standing dead trees ranged from 1 to 4 trees/ha. Larger forest fragments presented more living LTs, which were healthier and contain more biomass than LTs in small forest fragments. We found that edge effects were stronger than size effects for standing dead LT abundance; we found more dead trees up to 200 m from forest edge, independently of fragment size. Almost all living LTs had some health problem. The most frequent health problems were partial crown death, liana and termite infestation. Results suggests also that hard-wooded, slow-growing species tend to be replaced by soft-wooded, gap specialist species, coupled with an overall decline in LT density in small forest fragments, as well as in forests that suffered logging. Long-term prospects for these big carbon stocks are not encouraging, and given the low abundance of LTs in more degraded sites, strategies of intervention in large, century-old individual trees should be considered, such as liana infestation control and edge effect mitigation, in order to avoid further biodiversity and carbon losses.