Impact of Sericostachys scandens on forest regeneration in the Kahuzi-Biega National Park, D.R.Congo.
Background and aims - Sericostachys scandens (Amaranthaceae), an indigenous liana in Kahuzi-Biega National Park (KBNP, D.R.Congo), has been spreading strongly in montane forests for about ten years. We have tried to assess the consequences of this expansion on forest regeneration. Methods - We carried out an inventory of tree individuals (≥1 m in height) growing in 33 gaps in the montane forests located between 2083 and 2424 m altitude. Based on three age classes of gaps (1996, 2000 and 2004), the inventory was carried out in the plot of 10 m × 10 m, in sites invaded and non invaded by Sericostachys scandens. The EstimateS software was used to calculate the expected number of plant species in order to plot cumulative species richness curves. The relative frequency of species and the Simpson index of diversity were calculated for the two types of vegetation (invaded vs. not-invaded). Results - Irrespective of gap age, cumulative curves obtained from the expected number of plant species show that plots without Sericostachys scandens are richer in species than those with the liana. The values of relative frequency of species, and Simpson index obtained are highest in forest gaps without the liana. The impact of the liana is larger in more recent gaps. Conclusions - The results of this research show that Sericostachys scandens has a negative impact on tree species richness in forest gaps of KBNP.