Spatio-Temporal Organization and Biomass Dynamics of Plant Communities in a Dry Tropical Peri-Urban Region:Deterministic Role of Alien Flora in Anthropo-Ecosystems

The species nativity, growth form, habit, invasion status, aboveground biomass (AGB) and belowground biomass (BGB) distribution and soil characteristics across six diverse habitat conditions were studied in a peri-urban region in Indian dry tropics to understand their deterministic impact on vegetation structure. Eighty-seven plant species, predominantly annuals (67%), belonging to 28 angiosperm families were recorded. Among them, 89% were exotics (largest of American and Asian origins) and 48% of the exotics were invasives while 16% were naturalized. AGB of annuals was higher than perennials, but the difference in their BGB was insignificant. Compared to natives, the exotics had higher AGB and BGB. Among them, the AGB species of South America, Asia and the Indian subcontinent had higher AGB, but the order was reversed in case of BGB. Similarly, AGB of invasives was higher than natives, but they showed comparable BGB. 'Non-native annual forbs' were the most dominant functional groups in terms of both AGB and BGB. The ordination results varied with plant BGB and AGB. Canonical correspondence analysis indicated dominant role of exotic invasives (mainly of American and European origin) and significant influence of soil organic carbon (SOC) and total nitrogen on vegetation organization. At lower SOC, AGB and BGB were comparable for both native and exotics. However, with the increase in SOC, native AGB and BGB declined, whereas AGB of nonnative species increased. In conclusion, the study revealed large intrusion of alien floras into anthropoecosystems in Indian dry tropics, which significantly impacted structure and ecological processes both aboveground and belowground, as against better adaptation potential of the natives belowground.