Western lowland gorilla an logging companies A winning duo ?

The critically endangered western lowland gorilla (WLG) disperses the seeds of many fruits. These seeds are often deposited at gorilla nest sites, in open-canopy habitats favorable for seedling growth and recruitment. However, considering anthropogenic disturbances, such as logging, gorillas and the directed seed dispersal services they provide are at risk. On the other hand, sustainably managed logging concessions are reported to harbor viable gorilla populations. If WLG provide effective dispersal of timber species, it would be of benefit to loggers for these ecological services to be preserved. In order to explore such interactions between the WLG and the timber industry, we (1) assessed the status of a WLG population in a logging concession, and (2) investigated their seed dispersal effectiveness for timber species.
We inferred the long-term viability of a gorilla population in a Gabonese logged forest, and the short-term impact of timber harvesting on this population. Gorilla density was estimated through three successive censuses: (1) 25 years after the first felling cycle, (2) six months and (3) one year after the second felling cycle. Seed dispersal effectiveness for timber species was estimated through gorilla fecal analysis and germination trials in a nursery.
The results suggested that a viable population of WLG could be maintained in selectively logged forests (< 2 cut trees ha-1). Indeed, although gorillas tend to flee areas being actively exploited for timber, their densities in logged forests can regain their initial levels, or even a higher one, within one year post-logging. Over a period of 20 months, the seeds of 59 plant species were found in gorilla feces. Nearly 20 % of the identified species (N=35) are of economic value because of their exploitation for timber. Analyzed fecal units contained on average 81.0 ± 107.8 intact seeds (0-566). Specific germination success varied from 0 to 100 %, with an average of 46 ± 36 %.
Sustainably-managed logging concessions may host viable populations of WLG. Considering the seed dispersal services provided for timber species and the unique directed-dispersal to open-canopy habitats, gorillas are implicated in the regeneration and maintenance of logged forests. Therefore, the generalization of sustainable logging would be beneficial both to the economical and the environmental value of tropical forests, thus providing an incentive for loggers and governments to prevent illegal hunting in concessions.