An Invasive Ecological Study on the Flora of Soil Seed Bank and Standing Vegetation Across Diverse Anthropo-ecosystems in Indian Dry Tropics

Plant invasions in tropical ecosystems are being increasingly realized particularly in highly dynamic but fragile dry tropical ecosystems, where there is generally little ecological information on invasions in subterranean vegetation. The present study was carried out to understand the floristic composition of both seed bank and standing vegetation across a range of five diverse anthropo-ecosystems in an urban region in Indian dry tropics. A total of one hundred soil samples (each of size of 25cm×25cm from 0-5 cm and 5-10 cm depth) from five anthropic sites (vegetation of University campus, polluted Kali River bank, Brick kiln, Waste land and Road side) were analyzed for their taxonomic position, life form and bio-geographic origin of the seedling emergents in relation to the flora in standing vegetation. A total of 221 plant species (58% aliens, 34% of aliens of American origin, 75% weedy herbs) in standing vegetation spread over 54 families were recorded in standing vegetation of the study sites with more than 55% representation from eight dominant families led by Fabaceae, Poaceae and Asteraceae followed by Malvaceae, Amaranthaceae and Solanaceae. In contrast, a total of 81 seed bank flora (10 unidentified, 62% aliens, 43% of American origin, 87% herbs) distributed over 32 angiospermic families were recorded. While none of the seed bank vegetation at any site showed significant similarity with its standing vegetation indicating the minor role of seed bank flora in the regeneration of the standing plant communities above ground. However, a considerable similarity among seed banks and standing vegetation at other sites indicated a significant possible role of anthropogenic activities in the urban regions of Indian dry tropics, evinced by the largest proportion of grasses and herbs dominated by exotics, especially of American origin. These aliens through successful naturalization via seed banks may cause homogenization of floristic structure. In conclusion, the present study revealed a heavy scale of intrusion by the alien plants dominated by American elements into not only standing vegetation but also in seed banks across the anthropic sites in urban regions in Indian dry tropics which is likely to alter the standing vegetation floristic structure with a larger abundance of alien flora.