Arvind Kumar Jha

Spoil characteristics and vegetation development of an age series of mine spoils in a dry tropical environment

A series of coal mine spoils (5, 10, 12, 16 and 20-yr old) in a dry tropical environment was sampled to assess the changes with time in spoil characteristics, species composition and plant biomass. Coarse fragments (>2 mm) decreased with age of mine spoil while the proportion of 0.2–0.1 mm particles increased. Total soil N, mineral N, NaHCO3-extractable Pi, and exchangeable K increased with age of mine spoil and these parameters were lower in mine spoils than native forest soil even after 20 years of succession. Exchangeable Na decreased with age of mine spoil and in 20-yr old spoil it was higher than native forest soil. Plant community composition changed with age. Only a few species participated in community formation. Species richness increased with age, while evenness and species diversity declined from 5-yr old to 16-yr old community with an increase in the 20-yr old community. A reverse trend occurred for concentration of dominance. Area-weighted shoot and root biomass of other species increased with the age of the mine spoil while that of Xanthium strumarium patches declined with age. Data collected on spoil features, microbial C, N and P, and shoot and root biomass when subjected to Discriminant Analysis indicated a continued profound effect of age. 10 and 12-yr old mine spoils were closer to each other, and 5 and 20-yr old spoils were farthest apart.

Influence of microsites on redevelopment of vegetation on coalmine spoils in a dry tropical environment

An age series of mine spoils (5, 10, 12, 16 and 20 years old) in a dry tropical environment was studied to assess the impact of different microsites (substrate conditions) on physico-chemical and biological characteristics of spoils, and on species composition and plant biomass levels. Impact of microsites, even after 20 years of soil and vegetation redevelopment, remained important. Undulating surface and flat surface microsites showed more or less a similar behaviour after 20 years of succession and were better habitats than slope and coalpatch margin microsites for plant growth. The present study indicated that microsite conditions should be taken into consideration in any revegetation programme and desired natural colonizing species of even higher successional order may be used to accelerate the natural revegetation process according to the post-mining land use objectives.

Influence of a developing tree canopy on the yield of Pennisetum pedicellatum sown on a mine spoil

. Shoot and root biomass yield of a sown grass, Pennisetum pedicellatum, were measured at below-canopy, canopy edge and open locations in young monoculture stands of eight tree species planted on a coalmine spoil. Incident light as percentage of full sunlight decreased from open to canopy edge to below-canopy locations. The shoot and root weights of Pennisetum in different tree stands for each of the three locations were significantly different and were significantly related to each other, and to percentage sunlight across all tree species plots and locations. The gradient of incident light was the principal factor governing the gradient of grass biomass under developing canopies of tree plantations on the mine spoil.