AimThe invasive herb Ageratina riparia (Regel) R. M. King & H. Rob. (Asteraceae) which is a noxious weed is spreading rapidly in the forest gaps, edges and along the footpaths inside montane forests in Knuckles Forest Reserve(KFR), Sri Lanka. Since A. riparia forms thick mats in the ground layer of montane forests, its spread can be detrimental for the establishment of seedlings of species.But the ecological status of this weed in Sri lanka is not studied so far.
MethodsThe research duration was Sep 2011 to June 2012 at the KFR. Six forest gaps and four footpaths inside montane forests where A. riparia is grown were selected. In each gap, five quadrats (1 m×1 m) were established. For each footpaths 6 quadrats (1 m×1 m) were laid (Total 54). The percentage cover of A. riparia, number of seedlings of forest species,soil moisture content, soil root density, root moisture content and canopy openness were determined.
ResultsThe mean density of seedlings of forest species showed a negative relationship with percentage cover of A. riparia. This weed can cause higher underground competition for water and nutrition, suppressing the growth of the native forest species. The Four most abundant forest species growing in A. riaparia stands are Psychotria ceylanica, Symplocos cochinchinensis, Sacandra chloranthoides, and Semecarpus walkeri.
ConservationA. riparia threatens the regeneration of the forest species. Their spread must be controlled. Hence further spreading of the weed into the forest interior should be prevented and come up with restoration strategies using native forest tree species. Native forest species including Psychotria ceylanica and Symplocos cochinchinensis Sacandra chloranthoides, and Semecarpus walkeri can be used to restore degraded montane forest patches without removing A. riparia.