Gray-headed Lemur (Eulemur cinereiceps) abundance and forest structure dynamics at Manombo, Madagascar

Madagascar's ecosystems are subject to high levels of anthropogenic disturbance and stochastic events, including cyclones. We investigated the abundance of gray-headed lemurs (Eulemur cinereiceps) and vegetation structure in the fragmented forest of Manombo from 1995 to 2007, including 10yr following Cyclone Gretelle in January 1997. We predicted that the density of this arboreal, frugivorous lemur would be similar in the pre- and post-cyclone intervals only if tree measures demonstrate trends toward recovery in the post-cyclone period. Initial impacts included severe damage to over 60 percent of trees. After 10yr, all vegetation metrics except for stem density remained low relative to the pre-cyclone period, including dbh, height, and basal area. To investigate vegetation changes separately from cyclone effects, we compared forest structure in the pre-cyclone period alone. Basal area declined but dbh and stem density did not vary between 1995 and 1997; thus, anthropogenic activities or other factors did not consistently alter forest structure in this 2-yr period. Subsequent changes may be linked to cyclone response, presumably in synergy with human disturbance. Contrary to predictions, recent gray-headed lemur population densities were nearly identical to those recorded in 1995 (13.5 ± 3.2 vs. 13.6 ± 6.4 individuals/km², respectively). Lemur populations may have remained stable or declined initially and then recovered in the last 10yr. Life history and ecological adaptations may explain their resistance or resilience when faced with habitat change. Recent models suggest that lemurs have evolved in response to unpredictable environmental conditions. Such environmental variability may increase with projected climate change.