Zhang Peng, Huang Lei, Hu Yi-gang, Zhao Yang, Wu Yong-chen
Ying Yong Sheng Tai Xue Bao. 2016 Feb;27(2):436-44.
Nitrogen limitation is common in terrestrial ecosystems, and it is particularly severe in damaged ecosystems in arid regions. Biological soil crusts (BSCs) , as a crucial component of recovered vegetation, play a vital role in nitrogen fixation during the ecological restoration processes of damaged ecosystems in arid and semi-arid regions. In this study, two dominant types of BSCs (i.e., cyanobacterial-algal crusts and moss crusts) that are widely distributed in the re-vegetated area of Heidaigou open pit coal mine were investigated. Samples were collected in the field and their nitrogenase activities (NA) were measured in the laboratory. The responses of NA to different hydro-thermal factors and the relationships between NA and herbs in addition to crust coverage were analyzed. The results indicated that BSCs under reconstructed vegetation at different succession stages, abandoned land and natural vegetation showed values of NA ranging from 9 to 150 µmol C2H4 . m-2 . h-1, and the NA value of algae crust (77 µmol C2H4 . m-2 . h-1) was markedly higher than that of moss crust (17 µmol C2H4 . m-2 . h-1). In the re-vegetated area, cyanobacterial-algal crust and moss crust under shrub-herb had higher NA values than those of crusts under arbor-shrnb and arbor-shrub-herb. The relationship between NA of the two BSCs and soil relative water content (10% - 100%) as well as culture temperature (5-45 °C) were of quadratic function. With elevated water content and cultural temperature, the NA values increased at the initial stage and then decreased, and reached the maximum value at 25 °C of cultural temperature and 60% or 80% of relative water content. The NA of cyanobacterial-algal crust had a significant quadratic function with herb coverage, as NA declined when herb coverage was higher than 20%. A significant negative correlation was observed between the NA of moss crusts and herb coverage. The NA values of the two types of BSCs had a significant positive correlation with crust coverage, since the NA was enhanced when the crust coverage was increased. We concluded that the different NA of the two BSCs in the re-vegetated area of Heidaigou open pit coal mine were caused by the composition of cryptograms. In addition, the differences of hydrothermal conditions and the composition of herb or crust coverage at different succession stages were also the contribution factors. Therefore, BSC construction and nitrogen fixation in re-vegetated areas is an important symbol for sustainable development in ecosystems.
氮素限制在陆地生态系统中很常见，在干旱地区受损生态系统中尤为严重。生物土壤结皮（BSCs）作为植被恢复的关键组成部分，在干旱和半干旱地区受损生态系统的生态恢复过程中，对固氮起着至关重要的作用。本研究调查了黑岱沟露天煤矿复垦区广泛分布的两种优势生物土壤结皮类型，即蓝藻-藻类结皮和苔藓结皮。在野外采集样本，并在实验室中测定其固氮酶活性（NA）。分析了NA对不同水热因子的响应以及NA与草本植物除结皮覆盖率之外的关系。结果表明，处于不同演替阶段的重建植被下、弃耕地和自然植被下的生物土壤结皮的NA值范围为9至150 μmol C2H4·m-2·h-1，藻类结皮的NA值（77 μmol C2H4·m-2·h-1）明显高于苔藓结皮（17 μmol C2H4·m-2·h-1）。在复垦区，灌草下的蓝藻-藻类结皮和苔藓结皮的NA值高于乔灌和乔灌草下的结皮。两种生物土壤结皮的NA与土壤相对含水量（10% - 100%）以及培养温度（5 - 45℃）之间的关系呈二次函数。随着含水量和培养温度的升高，NA值在初始阶段增加，然后下降，在培养温度为25℃、相对含水量为60%或80%时达到最大值。蓝藻-藻类结皮的NA与草本植物覆盖率呈显著二次函数关系，当草本植物覆盖率高于20%时，NA下降。苔藓结皮的NA与草本植物覆盖率之间存在显著负相关。两种生物土壤结皮的NA值与结皮覆盖率呈显著正相关，因为结皮覆盖率增加时，NA增强。我们得出结论，黑岱沟露天煤矿复垦区两种生物土壤结皮的不同NA是由隐花植物的组成引起的。此外，不同演替阶段水热条件的差异以及草本植物或结皮覆盖率的组成也是影响因素。因此，复垦区生物土壤结皮的构建和固氮是生态系统可持续发展的重要标志。
