Impacts of Invasion by Ageratina adenophora on Soil Properties and Plant Diversity

Abstract

Ageratina adenophora, one of the most noxious invasive plants globally, is found to have escaped into novel ecological ranges in Bhutan. As such, this study was an attempt to assess the impacts on soil properties, community abundance, plant diversity and invasion intensity within the study area spanning the Punakha and Wangdue Phodrang districts. The study was conducted along the roadsides sampling at an interval of 5 kilometres. At this interval, two circular plots were drawn, the invaded and uninvaded, and collected plant and soil samples from both the plots. While there was no clear impact of invasion on soil properties, the diversity index and abundance clearly showed that invasion had reduced the diversity and abundance at the lower community level, particularly at the herb level. The invasion intensity analysis also showed that the study area has favourable environmental conditions for higher intensity of invasion. In sum, the study implied that this species if not managed, would lead to loss of other resident plants, particularly at the lower community levels due to its cosmopolitan characteristics.