不同区域和海拔高山寒漠带垫状植物覆盖下表层土壤的主要理化性质

Study on physical-chemical properties of topsoil under cushion plants in different climate and elevation zones of alpine cold desert

【目的】垫状植物能通过改善土壤理化性质来影响寒漠带生态系统物种多样性和稳定性。然而,高山寒漠带垫状植物对土壤理化性质的改善是否具有普遍性目前还不清楚。【方法】选择白马雪山垭口(BM)、昆仑山口(KL)、祁连山七一冰川(QL)和乌鲁木齐河源区(TS)的典型高山垫状植物群落为研究对象,分析优势高山垫状植物下土壤理化性质(pH值、电导率、有机质、全氮、全磷、碱解氮和速效磷)与开放区域的差异性。【结果】与开放区域相比,垫状植物的存在能够明显改善土壤的pH值,在酸性较大的土壤中,垫状植物能增加pH值(BM2:5.38增加到7.10),而在碱性较高的土壤中,垫状植物的存在能明显降低土壤的pH值(KL、QL和TS的样地中pH值降低幅度为5.78%~12.77%;P<0.05)。除了全磷和速效磷在TS的3个样地中显著低于开放区域外,垫状植物的覆盖显著改善了土壤的养分状况(电导率和养分含量),测定的各个养分指标均高于开放区域,且多数土壤养分指标的增加较为显著(P<0.05)。以土壤有机质含量为例,4个研究区的12个高山垫状植物群落中,垫状植物覆盖下土壤的有机质含量最低增加了36.89%(BM1),最高增加了981.91%(QL2)。【结论】尽管不同气候带的土壤理化性质差异较大,但垫状植物对其冠层下土壤的改良效应具有普遍性。作为高山寒漠带植物群落的关键种,高山垫状植物对土壤环境的这种改善作用可能是其维持冰缘带脆弱生态系统物种多样性的基础。

【Objective】Cushion plants can affect the species diversity and stability of ecosystem by improving soil physical and chemical properties in alpine cold desert.However,it is not clear whether the impact of alpine cushion plants on soil physical and chemical properties is of universality.【Method】The study employed alpine cushion plants from Baima Snow Mountain(BM),Kunlun Mountain(KL),Qilian Mountain(QL)and Urumchi River source region(TS)in China as the materials,to investigate the difference of soil physical and chemical properties(pH,electrical conductivity,organic matter,total nitrogen,total phosphorus,alkaline nitrogen and available phosphorus)between under dominant cushion plants and open area in alpine cold desert.【Result】Compared to open area,the presence of cushion plants could significantly improve the pH value of soil(P<0.05).In acidic soil,cushion plants could increase the pH value(in BM2,pH value increased from 5.38 to 7.10),while they could reduce the soil pH value in alkaline soil.When compared with open area,the soil nutrients and electrical conductivity were significantly increased under most cushion plant(the reduction of pH value ranged from 5.78%to12.77%in KL、QL and TS;P<0.05).Except for the total phosphorus and available phosphorus that were significantly lower in the three TS sites than in the open area,the coverage of cushion plants significantly improved the soil nutrient status(electrical conductivity and nutrient content),with all measured nutrient indicators being higher in the TS sites than in the open area and most of them being significantly increased(P<0.05).With soil organic matter as an example,its lowest content increased by 36.89%(BM1),and the highest content increased by 981.91%(QL2)in 14 communities of cushion plants of four study sites.【Conclusion】Although the significant difference in soil physicochemical properties,the presence of cushion plants could improve soil environments across different climatic zones.As the key species in plant community in alpine cold desert zone,cushion plants probably play a critical role in maintaining species diversity in the periglacial fragile ecosystem through improving soil environment.