围封对不同退化程度荒漠草原植物群落和土壤的影响

围封是退化草原生态系统恢复的有效措施之一，已在中国北方草原地区实施多年并取得良好的效果。由于不同退化草原生态系统具有完全不同的植被和土壤条件，围封对不同退化草原植物群落和土壤的恢复是否具有一致的影响，目前仍不清楚。对内蒙古地区轻度、中度和重度退化荒漠草原分别设置6年围封后，对植物群落特征和土壤理化性质进行了调查和测定。研究结果发现，围封显著提高了3种退化荒漠草原短花针茅（Stipa breviflora）和无芒隐子草（Cleistogenes songorica）种群以及群落的高度、盖度和地上生物量（P<0.05），表明围封从多组织层次使退化草原植物群落得到有效的恢复。围封总体提高了轻度和中度退化荒漠草原植物多样性，但降低重度退化荒漠草原的植物多样性。重度退化荒漠草原在围封后群落高度、盖度和地上生物量恢复效率显著高于轻度和中度退化的（P<0.05），表明围封对重度退化荒漠草原植被恢复更加有效。除轻度退化外，围封显著降低中度和重度退化荒漠草原土壤全碳、全氮、全磷、有效氮和速效磷含量（P<0.05），但对3种退化荒漠草原的土壤水分含量无显著影响，表明围封对不同退化荒漠草原土壤的影响具有滞后性。研究为荒漠草原围封成效评估提供理论指导和退化荒漠草原生态系统科学合理实施围封政策提供科学依据。

Effects of fencing on plant community and soil properties of temperate desert steppe along the different degradations

Fencing is one of the effective techniques to restore degraded steppes, which has been applied in the steppes of north China for many years. Due to different vegetation and soil conditions in lightly, moderately, and heavily degraded steppes, it is still unclear whether fencing has a consistent effect on plant community and soil properties of the steppes along the different degradations. We conducted a six-year fencing experiment in lightly, moderately, and heavily degraded desert steppes in the Inner Mongolia, China and measured the plant community and soil properties in the growing season of 2021. The results showed that fencing significantly increased height, cover, and aboveground biomass at population (i.e., Stipa breviflora and Cleistogenes songorica) and community levels (P<0.05), which drove the vegetation restoration of degraded desert steppe from multiple organization levels. Fencing generally increased plant diversity of the lightly and moderately degraded desert steppes but decreased that in the heavily degraded desert steppe. The recovering efficiency of community height, cover, and aboveground biomass in the heavily degraded desert steppe was significantly higher than those in the lightly and moderately degraded desert steppes (P<0.05), indicating that fencing had more effective for vegetation restoration in the heavily degraded desert steppe. Moreover, except for the lightly degraded desert steppe, fencing significantly decreased soil total carbon, total nitrogen, total phosphorus, available nitrogen, and available phosphorus concentrations of moderately and heavily degraded desert steppes (P<0.05), but had no remarkable effect on soil moisture along the three degraded desert steppes. This result showed that fencing had lag effects on soil physical and chemical properties compared with plant community. Our study provides theoretical guidance for evaluating the effects of fencing on desert steppe and scientific basis for implementing fencing policies accurately in the degraded desert steppe ecosystems.