植被重建对露天煤矿排土场土壤酶活性的影响

植被重建是露天煤矿排土场生态恢复的关键措施,深入了解植被建设对土壤酶活性的影响,对于合理选择适宜于矿区生态恢复的人工植被和加速矿区土壤生态恢复具有重要意义。通过野外调查采样和室内分析,研究了黑岱沟露天煤矿排土场植被重建和恢复对浅层(0—20 cm)土壤酶活性(包括3种氧化还原酶:过氧化氢酶、多酚氧化酶、脱氢酶,4种水解酶:蔗糖酶、脲酶、磷酸酶、纤维素酶)的影响。结果表明:相比未进行植被建设的新排土场裸地,植被重建显著改善了土壤酶活性和理化性质,建植18a后土壤酶活性可恢复到天然植被区的65%—76%,水解酶恢复速率(平均为86.9%)快于氧化还原酶(平均为42.7%),其中土壤磷酸酶恢复速率最快(平均为天然植被区的154.7%),其次为蔗糖酶(74.3%)、纤维素酶(59.9%)、脲酶(58.5%)、过氧化氢酶(52.1%)和脱氢酶(38.1%),多酚氧化酶恢复最慢(为37.8%)。植被恢复进程中,建植10a期土壤酶活性年均恢复速率最快(平均为6.0%/a),15a变缓(4.8%/a),18a迅速降低(3.2%/a)。同时植被配置类型对土壤酶活性影响显著,土壤酶活性与土壤主要理化因子具有较高的相关性。上述结果反映了植被重建能显著改善矿区排土场的土壤酶活性,植被恢复进程中水解酶恢复速率快于氧化还原酶,恢复初期快于后期,但土壤酶活性的恢复需要一个漫长的过程。

Effect of revegetation on soil extracellular enzyme activity in the dumping site of an open-pit coal mine in Heidaigou

Soil enzymes are considered a key component of the soil, mediating the decomposition of organic matter and catalyzing key transformations of carbon, nitrogen, and phosphorus cycling. In addition, extracellular enzyme activities (EEAs) in soil can be used as a measure of soil health. Revegetation is an important method of promoting the ecological restoration of a damaged ecosystem; however, little research has been conducted on EEAs in arid areas during vegetation restoration and after revegetation. To elucidate the differences in EEAs among different vegetation types and restoration stages in the dumping site of an open-pit coal mine in Heidaigou in northwest China, different revegetation types (including revegetation established in different years-a bare plot in a new dump, an abandoned area, and natural vegetation) were selected in order to investigate the recovery of EEAs (including three types of oxidases-catalase, polyphenol oxidase, and dehydrogenase, and four types of hydrolases-invertase, urease, phosphatase, and cellulose). The results show that revegetation significantly improves both the soil''s physical-chemistry properties and the EEAs in dumping sites when these properties are compared to those of bare land. After 18 y of revegetation, the EEAs in the topsoil (0-20 cm) recovered to 65%-76% of that seen in the plot with natural vegetation. The recovery rates of hydrolases (average 86.9%) were greater than those of oxidases (average 42.7%), and the recovery rates of EEAs exhibited a decreasing trend from phosphatase (154.7%), invertase (74.3%), cellulase (59.9%), urease (58.5%), catalase (52.1%), and dehydrogenase (38.1%), to polyphenol oxidase (37.8%). During the restoration process, the annual recovery rate of EEAs in the first 10a (averaged 6.0%/a) was greater than that seen 15a (4.8%/a) and 18a (3.2%/a) after revegetation. Significant relationships were observed between EEAs and soil nutrients; therefore, EEAs could be used as biological indicators when assessing soil quality. Our study indicates that EEA recovery occurs over an extended period, and that specific enzyme activities can be used to examine the changes in microbial physiology under different revegetation types in an arid mining area.