Impact of Plantation on Ecosystem Development in Disturbed Coal Mine Overburden Spoils

background

This study evaluates the growth, survival, understory composition, and soil conditions in a plantation established on a mine site in India.

Research Goals & Methods

Before this study, a trial was conducted to test 57 species grown in a potted mixture of overburden spoil and farm manure. The seedlings were evaluated for 6 months, and the 12 species that had the highest growth and survival (11 nitrogen-fixing, 1 non-nitrogren-fixing) were selected.  Three month old seedlings were planted in pits in which dump material and farm yard manure was mixed. Height, collar diameter, biomass (leaf, stem, branch) were measured for eight years and included in an index of overall performance. The pH values, organic carbon, available nitrogen, and levels of microbes were also evaluated from soils in each treatment.

Conclusions & Takeaways

Acacia mangium, Acacia holosericia, Dalbergia sisso, Albizia procera, Pithecellobium dulce, Acacia auriculiformis and Gmelina arborea were ranked the highest performers. . All were N-fixers except for Gmelina arborea. Acacia nilotica had the poorest height growth (5.25m), collar growth (10.8cm), and biomass production (2.40 kg per tree), while Acacia mangium had the greatest height growth, collar growth (23.9 cm), and biomass production (91.80 kg per tree). Available N contact was highest below Acacia holosericia, Pongamia pinnata and Albizia procera. The authors also evaluated community structure of regenerating species after the plantation establishment. Forty-six species were observed after 8 years of planting, and 9 species had been present from year 1 until year 8. Cassia tora, a leguminous and nitrogen-fixing colonizer, had the highest presence in the spoils after one year. Xantium strumariaum was dominant in the plantation for the first four years, but decreased afterward when the area was taken over by Eulaliopsis binata. Argemoney mexicana and Hyptis suaveolens were also highly present in the regenerating community. The authors found that organic matter and nitrogen were good indices for microbial activity. Their results suggest that planting suitable species in degraded mine sites can promote afforestation, enhance the soil conditions and the overstory conditions for recruitment of other species.