Subjects: Biology >> Ecology submitted time 2023-05-30 Cooperative journals: 《干旱区研究》
Abstract： Many studies on grassland ecosystem degradation have been performed using vegetation coverage orproductivity indexes for evaluation. However, it is difficult to comprehensively evaluate different degrees ofgrassland degradation using a single evaluation index. Taking Bayinbuluk grassland in the Xinjiang TianshanMountains as a research object, a remote sensing method for evaluating grassland degradation based onstandardized processing sub- index coupling was proposed. The grassland vegetation coverage, average grasslayer height, and total grass yield were selected to determine the weight of the three indexes by principalcomponent analysis. The Min-Max standardized method was introduced to construct the grassland degradationindex (GDI). Finally, the degree of degradation of Bayinbuluk grassland in the Xinjiang Tianshan Mountains wasdetermined through Landsat image inversion and reasonable classification of the rate of change of grasslanddegradation index from 1986 to 2021. The results showed that GDIg has the best correlation with NDVI. In 2021,the proportion of undegraded area of Bayinbuluk grassland relative to the total area was 60.51%. The degree ofdegradation of different grassland types showed clear differences. The spatial distribution showed a trend of basinto mountain degradation. The GDIrs model could be applied to other years through the radiation registrationmethod. The degree of degradation of Bayinbuluk grassland significantly improved from 2000 to 2009 andslightly fluctuated from 2009 to 2021. The results of this research provide robust data support and a theoreticalbasis for guiding evaluation of the degree of degradation of Bayinbuluk grassland and protecting the grasslandecosystem.
Subjects: Environmental Sciences, Resource Sciences >> Other Disciplines of Environmental Sciences, Resource Sciences submitted time 2021-03-02 Cooperative journals: 《干旱区研究》
Abstract：沙生柽柳（Tamarix taklamakanensis）是我国特有种，是塔里木盆地流动沙丘上最抗旱树种，对固沙造林和荒漠化防治起到非常重要的作用。通过测定沙生柽柳种群在3种不同生境（沙漠公路绿化带、河床砾质荒漠、流动沙丘）的叶片含水量、叶绿素含量、抗氧化酶活性及渗透调节物质含量，探讨了沙生柽柳在不同生境下的生理生化特征及对荒漠极端干旱环境的适应机制。结果表明：随着土壤干旱程度的加剧，沙生柽柳叶片相对含水量逐渐下降；超氧化物歧化酶（SOD）活性、过氧化物酶（POD）活性、总抗氧化能力（T-AOC）逐渐升高；过氧化氢酶（CAT）与硝酸还原酶（NR）活性逐渐降低；种群叶片内可溶性蛋白呈上升趋势。在最为干旱的流动沙丘，种群叶片叶绿素a含量、可溶性糖含量最高。在干旱胁迫条件下，沙生柽柳种群主要通过增高SOD活性、POD活性、总抗氧化能力及降低过氧化氢酶（CAT）、硝酸还原酶（NR）含量以维持活性氧代谢平衡；同时，通过大量积累渗透调节物质可溶性糖、可溶性蛋白、丙二醛以维持高渗透调节能力抵御干旱环境胁迫。
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