This project examines the impact of the invasive liana, Sericostachys scandens, on forest composition and recovery of the Grauer's gorilla (Gorilla beringei graueri) in the Kahuzi-Biega National Park, Democratic Republic of Congo (DRC).
Sericostachys scandens is a keystone species, a semi-woody climber capable of growing 20-30 m in length (Troupin 1985 in Plumptre et al. 2002). In the 1990s, this species has come to dominate large expanses of the forest in Kahuzi-Biega National Park in Eastern Democratic Republic of the Congo and other mountain forests in the region (Fimbel 2004, WCS-Rwanda, unpub.). Where present, this liana has created a mono-dominant understory and mid canopy patches that cover large areas. In this project, I will examine S. scandens impact on forest composition with an emphasis on plant species preferred by the Grauer's gorilla, an endangered and protected species. I also aim to determine whether habitat loss and degradation by Sericostachys scandens affects gorilla use of this sector, and the possible implications for population recovery. Specifically, I will use a combination of remote sensing and field-based surveys to determine the current and historical Sericostachys cover area in the gorilla sectors. I will also measure the impacts of liana invasion by documenting the distance gorillas must forage per day in liana covered areas versus non invaded liana areas. I will test two hypotheses specific to the central role that Sericostachys imparts on forest composition and, in turn, presents a potential threat to gorilla habitat and, by extension, to the long-term survival of the Grauer's gorilla population.
Hypothesis 1: The invasion of Sericostachys in the upland sector of the national park has altered forest composition and suitable habitats for gorillas.
Hypothesis 2: Gorilla groups in Sericostachys liana dominated areas will spend more time foraging because they are faced with tangled, impenetrable vegetation which for them is inedible; therefore, the daily foraging time of gorillas under the leadership of the Silverback (gorilla male group leader) will increase while the distance traveled will decrease.