Introduction: What conservation problem or question does your study address?The highly degraded grasslands at the Knuckles Conservation Area (KCA) in Sri Lanka are rapidly invaded by Austroeupatorium inulifolium, a notorious invasive species. We investigated the potential impacts of Austroeupatorium invasion on forest-grassland edge (FGE) communities to find its role in restoration of these highly degraded grasslands.
Methods: What were the main research methods you used?A complete vegetation sampling was carried out in 2 forest-grassland interfaces that run across forest remnants bordered by highly-invaded (HIG) and less-invaded grasslands (LIG). The two forest-grassland interfaces hereafter will be known as FGE-HIG and FGE-LIG respectively. In each site (3 sites from each community), two sets of 5 linear quadrates (3 m x 12 m) were placed parallel to the FGE at different distances; 0 (edge), 5 and 10 m away from the edge towards the grassland and towards the forest interior. In addition, three grassland communities were also sampled: LIG, HIG and FGE using 4 m2 quadrates (6 per community).
Results: What are your most important results?From a total of 6361 individuals recorded in FGE-HIG, 430 were tree saplings while of 3479 individuals recorded at FGE-LIG, 182 were tree saplings belonged to 14 and 11 species respectively. The abundance and richness of tree saplings were significantly higher in the forest interior and in the open grassland bordered by HIG than that of LIG. In the second sampling, tree saplings were found only in HIG. The Shannon Diversity Index was highest at HIG than that of LIG and FGE.
Discussion: What are your important discussion points and what is the relevance of your results to conservation (if any)?Results suggested that Austroeupatorium invasion has a facilitative effect on tree seedling establishment by enhanced shading effect and improved edaphic conditions. It has the potential to change the community structure in forest-grassland edges and altering the vegetation community in the forest interior. This facilitative effect of Austroeupatorium invasion on the forest tree establishment needs further studies to verify its potential long-term effects.