Western lowland gorilla populations and logging concessions: is the coexistence possible?

Timber exploitation is rapidly expanding throughout the Congo Basin. Around 26 % of the moist forests are devoted to logging activities. Logging concessions largely overlap with the range of western lowland gorilla (WLG) considered as critically endangered by IUCN. However, this species could play an essential role in maintaining vegetal diversity notably through seed dispersal services. Particularly some tree species harvested for their timber may be dispersed by WLG.
In this communication interactions between WLG and a timber exploitation are studied in Central Gabon. WLG density is estimated in an Annual Allowable Cut (AAC), and nesting behavior is described. Seeds dispersed by WLG are identified through fecal analysis and germination trials are conducted to assess seed viability after gut passage. Four treatments are realized for the most abundant species: passed seeds, passed seeds in fecal matrix, seeds surrounded by fresh pulp and seeds extracted from fresh fruits.
A relatively high WLG density is observed in the AAC (2.0 weaned gorillas/km²). WLG nest preferentially in open terra firme forest and frequently use old logging road covered with herbaceous vegetation for nesting and feeding. They avoid nesting in closed terra firme forest. Seed dispersal and impacts of the passage in gorilla’s gut on seed germination are currently described. Germination success after gut passage depends on the seed species and varies from 0.0 to 100% in the course of monitoring time.
The first results of this study suggest that timber exploitation and WLG conservation are not mutually exclusive. WLG are important agents of forest regeneration by dispersing seeds in logged areas. Nest sites in logging gaps could be particularly favorable for seedlings development. This consideration must encourage forest managers to strengthen WLG-conservative practices in their concessions.