Rainforest fragmentation and the demography of the economically important palm Oenocarpus bacaba in central Amazonia

Abstract

We summarize a long-term study of the effects of edge creation on establishment of the economically important arboreal palm Oenocarpus bacaba in an experimentally fragmented landscape in central Amazonia. Recruitment and mortality of large individuals (>10 cm diameter-at-breast-height) were recorded within 21 1-ha plots in fragmented and intact forests for periods of up to 22 years. In addition, 12 small (0.7 x 14 m) sub-plots within each 1-ha plot were used to enumerate the abundance of seedlings and saplings (5-400 cm tall). On average, the recruitment of large trees was over two times faster near forest edges, leading to a sharp (90%) increase in the mean population density of large individuals near forest edges, whereas the density of larger trees remained constant in the forest interior. Overall seedling and sapling density was significantly lower in edge than interior plots, but edge plots had a much higher proportion of larger (>100 cm tall) saplings. Our findings demonstrate that forest edges can have complex effects on tree demography and that one must consider all tree life stages in order to effectively assess their effects on plant populations.

Disturbance and Resilience in Tropical American Palm Populations and Communities

“…However, the fact that only a few studies consider periods over five years (9% of the sample, Fig. 2; but see Brum et al, 2008) might question the consistency of the results for slow growing palms. Data at longer temporal scales are required in future research (Endress et al, 2006).…”

“…This negative edge effect at the community level (Baez & Balslev, 2007), may also impact palm dynamics through higher light intensity, altered distribution of dispersers and pollinators and mechanical disturbance such as increased numbers of tree-falls. However, a population study identified more complex effects, with a positive edge effect of habitat fragmentation on the density of saplings and adults in Oenocarpus bacaba (Brum et al, 2008). Therefore, studies at the community level have demonstrated an overall negative edge effect on palm fitness, but some species do benefit from this type of disturbance.…”

Too rare for non-timber resource harvest? Meso-scale composition and distribution of arborescent palms in an Amazonian sustainable-use forest

“…Previous studies suggest that arborescent palm communities are likely to change as a consequence of extraction (Steele et al, 2015), land-use change (Brum et al, 2008;Eiserhardt et al, 2011) and global warming (Bjorholm et al, 2005;Eiserhardt et al, 70 2011). Studying determinants of palm community structure and diversity is therefore central to Neotropical forest ecology and management.…”

“…have been recorded across a range of environmental gradients (Peres, 1994;Henderson et al, 1995;Svenning, 1999;Pacheco, 2001;Brum et al, 2008;Ter Steege et al, 2013).…”

“…Although there are methodological differences (such as the minimum DBH cut-off) previous studies report density values that are substantially (3 -DBH) O. bacaba was 5 ind. ha -1 within 21 central Amazon terra firme forest plots of 1 ha each (Brum et al, 2008).…”