Early Tree Growth in Reclaimed Mine Soils in Appalachia USA

Effects of Torrefied Wood Chips and Vermicompost on Tree Growth and Weed Biomass: Implications for the Sustainable Management of Salt-Affected Reclaimed Lands

A harsh environment, slow tree growth, nutrient deficiencies, and competition between trees and weeds can impede forest establishment on reclaimed lands. We investigated the effects of torrefied wood chips (TWC) and vermicompost (VC) soil amendments on the growth of Populus euramericana Guinier, weed biomass, and soil chemical properties on reclaimed land in Saemangeum. The 2.5 Mg ha−1 and 5.0 Mg ha−1 TWC had a similar effect on tree diameter and height growth (i.e., 2.5 = 5.0 > 0 TWC) and tended to have similar, higher effect on the total biomass of P. euramericana than the 0 Mg ha−1. The 2.5 Mg ha−1 TWC resulted in a significantly larger root biomass than the 5.0 Mg ha−1 TWC. The weed biomass was significantly larger at the 2.7 Mg ha−1 VC (i.e., 730.5–810.5 g m−2) than the control (605.1–610.6 g m−2), but VC alone was not effective for tree growth and soil amelioration. The TWC had no effect on weed biomass. Thus, the TWC and VC had contrasting effects on tree growth and weed biomass when they were used as soil amendments on salt-affected reclaimed land. VC application may promote weed proliferation, whereas TWC application may potentially increase the growth of P. euramericana and control weed growth on reclaimed lands. Our results enhance the existing knowledge on tree and weed responses to torrefied wood chips and vermicompost amendments for the sustainable management of salt-affected reclaimed lands.

Effect of Fast-Growing Trees on Soil Properties and Carbon Storage in an Afforested Coal Mine Land (India)

Surface coal mining activities have numerous consequences on terrestrial ecosystems. Loss of soil and biomass carbon pool due to mining activities is a serious concern in the rapidly changing environment. We investigated the effect of fast-growing trees (Albizia lebbeck, Albizia procera, and Dalbergia sissoo) on soil fertility and ecosystem carbon pool after eight years of afforestation in the post-mining land of Jharia coalfield, India, and compared with the adjacent natural forest site. Significant differences in soil organic carbon (SOC) and total nitrogen (TN) stocks in afforested mine soil and natural forest soils were observed. Greater SOC stock was found under D. sissoo (30.17 Mg·C·ha−1) while total N stock was highest under A. lebbeck (4.16 Mg·N·ha−1) plantation. Plant biomass accumulated 85% of the natural forest carbon pool after eight years of afforestation. The study concluded that planting fast-growing trees in post-mining lands could produce a promising effect on mine soil fertility and greater carbon storage in a short period.

The responses of soil bacterial communities and enzyme activities to the edaphic properties of coal mining areas in Central China

Soil physicochemical properties, bacterial communities and enzyme activities change with land subsidence resulting from coal mining. However, research on the responses of bacterial communities and enzyme activities to the soil properties in different degree of subsidence areas is limited. As such, we collected soil samples from a control area (C area), a moderate mining subsidence area (M area) and a severe mining subsidence area (S area) in Central China. Soil properties, such as the pH, total nitrogen (TN) content, total phosphorus (TP) content, available phosphorus (AP) content, organic matter (OM) content, and soil enzyme (urease, invertase, catalase and alkaline phosphatase) activities were measured in each sampling area at depths of 0-20 cm, 20-40 cm, and 40-60 cm. The results indicated that the soil physiochemical properties, soil urease activity, soil alkaline phosphatase activity and soil bacterial richness and diversity in the topsoil (0-20 cm) of the mining subsidence area were significantly lower than those in the C area. However, the soil enzyme activities within the deepest layer of the subsidence area were significantly greater than those of the C area. The bacterial communities within the depth of 0-20 cm were dominated by RB41, Pseudomonas, MND1, Nitrospira, Trichococcus, Sphingomonas and Dongia, whereas RB41 and Pseudomonas were the dominant species in the C area and subsidence area, respectively. Using correlation analysis, we found that the soil pH value, soil AP content and activities of the four enzymes were the main factors affecting the soil bacterial community structure. In addition, the soil nutrient contents, enzyme activities and bacterial richness and evenness decreased with increasing subsidence degree (classified by geological hazards, groundwater and landscape damage degree of coal mining subsidence). These results provide a reliable basis for environmental management of mining areas.