腾格里沙漠固沙造林后植被恢复对土壤节肢动物多样性分布的影响

Soil arthropod diversity plays implications on the stability of terrestrial ecosystem. There were vast number of literatures concerning geomorphology conformation, aeolian physics, vegetation dynamics and water deprivation, ecological hydrology, biological crust of Tengger Desert. However, there were limited knowledge on soil arthropod diversity and its relation with the stability of afforested desert ecosystem by long-term monitoring systematically. On the basis of Shapotou Desert Research & Experiment Station, Cold and Arid Regions Environmental and Engineering Research Institute, CAS, an investigation on soil arthropods (ground-active and meso- arthropods) was carried on in the afforested habitats with and without straw checkerboards, with straw checkerboards made by wheat, rice and nylon net, by seasonal afforestation, and along long-term chronosequence of stabilized plantation at the southeastern edge of Tengger Desert. The proposal was projected by: (1) the effects of the use of straw checkerboards with different materials as sand barriers on soil arthropod diversity; (2) the effect of seasonal afforestation on soil arthropod diversity; (3) the effect of timing of stabilized plantations on soil arthropod diversity. The aim of the projects would probe into the effects of vegetation restoration by afforestation on the distribution of soil arthropod diversity, and elucidate bioindicators of soil arthropods for artificial plant succession in Tengger Desert. All these results could provide the basis for the implications of desert plant afforestation on biodiversity restoration, the stabilization of sand-stabilized vegetation systems and for enriching the disciplines and content of desert ecology. In addition, the results could be benefical for the establishment of an optimal model of ecological engineering in arid desert regions.

土壤节肢动物多样性与陆地生态系统的稳定性密切相关。尽管已对腾格里沙漠地貌形态、风沙物理、植被动态与耗水规律、生态水文、生物结皮等开展了深入研究，但关于固沙造林后土壤节肢动物多样性分布及对固沙系统稳定性的维持机理，尚不清楚。本项目以腾格里沙漠造林方式（有、无草方格）、草方格材料（麦草、稻草、尼龙网）、造林季节以及长时间固沙植被序列为研究对象，主要研究：（1）造林方式及草方格材料实施后植被恢复对土壤节肢动物多样性分布的影响；（2）不同季节造林情况下植被恢复对土壤节肢动物多样性分布的影响；（3）不同固沙年限植被演替过程中土壤节肢动物多样性分布特征。研究结果旨在解析造林固沙过程中土壤节肢动物的生物指示作用，阐明固沙造林后植被恢复对土壤节肢动物多样性分布的影响规律，为深入理解沙漠植被建设对生物多样性恢复作用及人工固沙系统内稳性的维持机理、拓展荒漠生态学学科内涵及确立生态治沙最优模式提供科学依据。

开展固沙造林后植被恢复对土壤节肢动物多样性影响的研究，已成为沙漠植被对环境长期生态反馈影响研究系统监测和连续定位研究的重要内容。围绕固沙造林与土壤节肢动物多样性分布关系为切入点，开展固沙造林后植被恢复对土壤节肢动物多样性分布的影响研究，研究结果在理论上可以为荒漠生态学学科发展提供系统土壤动物学基础，在实践中可以为干旱沙漠区生态工程最优治沙模式提供理论支撑。主要开展研究内容如下：造林方式及草方格材料选择情况下植被恢复对土壤节肢动物多样性分布的影响；造林季节选择情况下植被恢复对土壤节肢动物多样性分布的影响；不同固沙年限情况下植被演替对土壤节肢动物多样性分布的影响。取得的重要结果包括：（1）腾格里沙漠东南缘草方格固沙林地长期演变促进土壤黏粒和粉粒及土壤分形维数显著增加，从而提高土壤有机碳和全氮含量，促进沙漠化治理。（2）腾格里沙漠东南缘固沙植被区沙丘大小、微地形对土壤理化性质及分形维数的作用效果存在较大的差异性，需要根据沙丘大小和微地形来开展人工林建设和生态效应评价。（3）腾格里沙漠东南缘沙障材料对地面节肢动物群落组成、个体数和类群数分布均产生显著影响，而且地面节肢动物群落组成分布亦受到沙丘微地形的影响，但沙障材料对地面节肢动物多样性分布的影响较小。（4）在腾格里沙漠人工固沙林，蚂蚁群落组成及数量特征对固沙过程可以起到指示作用，且蚂蚁筑巢行为有利于改善土壤质地，促进土壤理化性质向良好的方向发展，对实现荒漠生态系统恢复起到推进作用。（5）在榆林市榆阳区、盐池县、沙坡头固沙植被区，发现随降水量增加，灌丛微生境土壤细沙粒含量、土壤容重和土壤电导率降低，而土壤养分相对增加，草本植物物种数、个体数、高度均相对增加。说明降水量对灌丛的生态功能具有重要调控作用。（6）以榆阳、盐池和沙坡头为研究区，发现油蒿灌丛冠层节肢动物群落组成、个体数和类群数分布均受降水分布的影响较大，而多样性指数受到的影响较小。