Assessment of herbaceous community structure for identifying metal-tolerant species at different land uses in and around Varanasi city.

ABSTRACT

Plant community structure under different land uses provides an important understanding of vegetation dynamics to safeguard future restoration programmes and balance ecosystem services. Therefore, this study was carried out to estimate the alterations in soil properties and contamination by potentially toxic metals at different land uses (industrial, brick kiln, highway, and residential areas) compared to the reference (botanical garden area) site coupled with their subsequent influence on herbaceous community structure, bioconcentration, translocation, and extraction amount of metals in different plant species. Most of the total and phytoavailable metals (Co, Cr, Cd, Cu, Ni, Pb, Mn, and Zn) were higher at the contaminated sites compared to the reference site. The number of herbaceous species was highest at the reference site and minimum at the industrial site. Dominant and tolerant species were Cyanodon dactylon, Croton bonaplandianus, Achyranthus aspera, Malvestrum coromendelianum, Dicanthium annulatum, Nicotiana hindostana, Sporobolus virginicus, and Parthenium hysterophorus, found at the industrial, brick kiln, and highway sites. Based on transfer coefficients, C. bonaplandianus, D. annulatum, and Eleusine indica were recognized as potential accumulators, whereas C. dactylon, Commelina benghalensis, A. aspera, Amaranthus sessilis, and M. coromendelianum were found as excluder species for different metals. The identified tolerant herbaceous species could be used for future phytoremediation strategies and the prevention of hazardous risks to living components of contaminated sites.