Ecological Investigation on Plant Diversity and Soil Characteristics of Invasive Ageratum conyzoides and Introduced Eucalyptus globulus Ecosystems in an Indian Dry Tropical Region

Alien flora in urban ecosystems may have differing impacts on plant diversity and soil. In this study, vegetation and soil characteristics were investigated under the two contrasting herb layer conditions influenced by exotic invasive herb Ageratum conyzoides and introduced alien tree Eucalyptus globulus in an Indian dry tropical urban ecosystem. Phytosociological analysis of 120 randomly sampled quadrats (each of size 1m × 1m, n=60 at each site) was carried out. Nine random seasonal soil samples (0–10 cm) from both study sites were analyzed for soil pH, moisture content, organic carbon, total nitrogen, exchangeable Na, K and Calcium. A total of 82 species were recorded, representing 32 families. Poaceae and Fabaceae constituted dominant families. Cynodon dactylon dominated all sites and seasons. Number of rainy flora was comparable but varied distinctly in drier months. Alpha diversity, estimated higher at EG site in rainy season, ranked sites differently in drier months. Beta diversity, indicative of heterogeneity, was higher at AC sites in drier months in summer. Soil moisture content varied significantly with site and season. EG site recoded higher organic carbon and total nitrogen compared to AC site. In conclusion, the observed variations highlight the complex interplay of environmental factors, seasonal dynamics, and species interactions shaping plant community structure and composition and emphasize the need for further research to elucidate underlying mechanisms driving observed patterns.