Abstract:[Objective] The decomposition characteristics and influencing factors of plant litter for ecological restoration of a coal mining subsidence area were analyzed in order to provide a theoretical basis for restoration in an arid climate. [Methods] An one-year decomposition experiment that included three litter treatments (Salix psammophila; Populus simonii; 1∶5 ratio of S. psammophila∶P. simonii) and two decomposition soils (sandy soil, loess soil) was conducted in a coal mining subsidence area of Inner Mongolia using the field decomposition bag method. The residual dry mass and contents of organic carbon (OC), nitrogen (N), phosphorus (P), acid detergent fiber (ADF), and acid detergent lignin (ADL) of litter samples were determined once every two months. [Results] ① The decomposition rate of S. psammophila litter was significantly (p＜0.05) greater than the decomposition rates of P. simonii and the mixed treatment by 10%~15%. The litter decomposition rates in the loess area were significantly greater than in the sandy area by 13%~23%. ② The litter source had significant (p＜0.01) effects on OC, N, and P contents. Soil type had significant (p＜0.05 or p＜0.01) effects on OC, N, P, ADF, and ADL contents. Both tree species and soil type were important factors affecting the nutrient transformations of the litters. ③ The OC and N contents of S. psammophila litter were greater than those of P. simonii and the mixed litter. P content of P. simonii and the mixed litter were lower than the P content of S. psammophila litter during the first four months, and then the P contents of all of the treatments were similar. [Conclusion] P. simonii litter decomposed more slowly than S. psammophila litter, and therefore, can be maintained for a longer time on the surface of soil. Therefore, P. simonii is recommended to be used as a suitable restoration plant in the coal mining subsidence area of Inner Mongolia.

Abstract:Xinzhuangzi mining reclamation area, which located in Huainan City, was selected as the research area and seven soil enzyme activities(urease, phosphatase, invertase, protease, cellulose enzyme, hydrogen peroxide enzyme, polyphenol oxidase) were measured. The results showed significant differences among heavy metals pollution to seven soil enzyme activities. It was found that the seven soil enzyme activities were inhibited in different degrees, and the sensitivity of soil enzymes to heavy metals were not consistent. Factor analysis method was used to extract the principal component and establish evaluation index of the compound soil pollution of total enzyme activities which intended to evaluate the pollution degree of soil heavy metals in this area. The level of soil heavy metals pollution was obtained by grey clustering method. The relationship between soil enzyme activity and the heavy metal pollution in mining subsidence area were analyzed, which further proved it was feasible using the comprehensive index of soil enzyme activity to evaluate soil heavy metal pollution in special case of mining subsidence area. The overall evaluation index of soil enzyme activities, as a simple means of evaluation, will finally provide reference and theoretical basis to heavy metals pollution repairing in Xinzhuangzi reclamation area and similar coal mining area.

Abstract:The impact on soil and water conservation and ecological environment caused by large-scale coal mining subsidence area has aroused widespread concerns, and finding a new monitor method on water and soil loss caused by fully mechanized long-wall coal mining is of great significance. A new monitor method called monitor strips can be used on the monitoring of this mining subsidence area. The monitor strips is a timeseries and cross-space three-dimensional monitoring system with a reasonable layout of monitoring strip and comprehensive application of various monitoring measures, in considering with local conditions of topography, ground cover，transportation, agricultural production and other factors. It characterized by integrated arrangement and easy management，concentrated monitoring measures，comprehensive concerning of all monitoring items and with large amount of information. It is a useful attempt on the exploration and innovation of soil and water conservation monitoring, however it need further examination in practice.