Heavy Metal Contamination in Forest Reserved Soils Crossed by Roads, its Ecological Risks, and their Effects on Tree Biomass Stocking Potential

Abstract

Metal contaminants such as Cadmium, Chromium, Nickel, and Lead are released and deposited in Reserved Forest soils as a result of heavily travelled roads. Their pollution interrupts the biogeochemical cycle in the natural environment, affecting plant productivity. However, this pollution's source, their ecological risks, and its effects on tree biomass productivity have yet to be examined. In order to examine this, an ecological study was conducted in two Assam Reserved Forests that are crossed by the National Highway (NH-15). Several ecological risk indices were used to assess potential ecological risks. Metal impacts on tree biomass stocks were predicted using regression analysis and Pearson's coefficient. The results showed that metal concentrations in soil samples collected near roads were much higher than those away from roads. However, the overall mean concentration was within the Indian guidelines. Indices of soil contaminations and pollutions ranged from mildly contaminated to highly contaminated and from low polluted to highly polluted soils. The Cd (88.97%), and Pb (52.61%) were revealed to be highly the main contaminating and sources of pollution and ecological danger in the surface soils. The strongest Pearson correlation coefficients between Cd-Cr (94%), Cd-Ni (74%), Cd-Pb (97%), Cr-Ni (88%), Cr-Pb (90%), and Ni-Pb (76%) suggest that metals are very comparable. While the strong negative relationships between tree biomass stock and metals, implying that metals are vital factors affecting tree biomass productivity. Thus, conservationists, ecologists, and policymakers must devise effective mitigation strategies for vehicular emission and car discharge caused by traffic passing through reserved forests.