高寒沙区土壤结皮对浅层土壤理化性质的影响

Effects of soil crusts on physicochemical properties of shallow soil in alpine sandy area

土壤结皮是干旱沙区地表景观的重要组成部分,在沙化土地恢复和流沙固定中起着重要作用。为探究高寒沙区土壤结皮对浅层土壤理化性质的影响,文中以青海共和盆地小叶锦鸡儿灌丛间的裸沙、物理结皮、藻结皮、地衣结皮、苔藓结皮及其下层土壤(0~10cm和10~20cm)为研究对象,野外采样结合室内分析,研究其土壤颗粒组成和土壤养分水分特征。结果表明:结皮层的细颗粒物含量均显著高于灌丛间裸沙,表现为苔藓结皮>地衣结皮>藻结皮>物理结皮,结皮层细颗粒物均高于下层土壤;与裸沙相比,苔藓结皮层的有机碳、全碳、全氮、铵态氮、硝态氮和全磷含量分别增加4.60倍、7.32倍、3.64倍、1.75倍、3.61倍和0.40倍,土壤含水量增加5.68倍,结皮层养分含量均显著高于下层土壤(P<0.05);pH值表现为物理结皮>藻结皮>地衣结皮>苔藓结皮,在结皮层和不同深度的土壤层之间均无显著差异(P<0.05)。结皮厚度与土壤养分、含水量呈显著正相关,结皮盖度与土壤黏粉粒含量呈显著正相关,与沙粒含量呈显著负相关。不同类型的土壤结皮恢复指数均显著高于裸沙。因此,土壤结皮对于改善高寒沙区小叶锦鸡儿群落土壤的结构和质量具有积极作用,但随土层深度的增加,其影响逐渐减弱。

Soil crusts are important parts of the surface landscape in arid sandy areas,and play important roles in the restoration of desertified land and the fixation of shifting sand.In order to explore the effects of soil crusts on the physicochemical properties of shallow soil in the alpine sandy area,different types of soil crusts(bare sand,physical,algae,lichen and moss crusts)and their subsoil(0~10 cm and 10~20 cm)were collected in Caragana microphylla shrubs in Gonghe Basin,Qinghai province.Field sampling and indoor analysis were used to study soil particle composition and soil nutrient and moisture characteristics.The results showed that:the content of fine particles in the soil crusts was significantly higher than that in the bare sand among shrubs,which showed the order of moss crusts>lichen crusts>algae crusts>physical crusts,and the fine particles in the soil crusts were higher than that in the subsoil.Compared with bare sand,the contents of organic carbon,total carbon,total nitrogen,ammonium nitrogen,nitrate nitrogen and total phosphorus in moss crusts increased 4.60 times,7.32 times,3.64 times,1.75 times,3.61 times and 0.40 times,respectively,and the soil water content increased 5.68 times.The nutrient contents in different types of soil crusts were significantly higher than those in the subsoil(P<0.05).The pH values ordered as physical crusts>algae crusts>lichen crusts>moss crusts,and there was no significant difference between the crust layers and their subsoil at different depths(P>0.05).Soil crust thickness had significant positive correlation with soil nutrient and water content,whereas soil crust coverage had significant positive correlation with the content of silt and clay,and significant negative correlation with the content of sand.Soil restoration index in different types of soil crusts were significantly higher than that in bare sand.Therefore,soil crusts had positive effects on improving soil structure and quality of Caragana microphylla community in alpine sandy area,but the effect gradually decreased with the increase of soil depth.