荒漠区食细菌线虫对生物土壤结皮下土壤酶活性的影响

Effects of soil bacterial-feeding nematodes on soil enzyme activity under biocrusts in desert areas

作为土壤的重要生物组分,食细菌线虫影响土壤的能量流动和物质循环,但它在荒漠生态系统的作用仍不清楚。为探明土壤食细菌线虫对荒漠区土壤的影响,以腾格里沙漠东南缘人工植被固沙区生物土壤结皮覆盖的沙丘土壤为研究对象,分别采集藻-地衣和藓类结皮及结皮下0—10 cm土样,按每克土壤10、30、60、90、120、150条的密度接种食细菌线虫,以未接种线虫的土壤为对照,测定接种食细菌线虫后土壤脲酶、蔗糖酶、脱氢酶和碱性磷酸酶活性的变化,明确食细菌线虫对荒漠区土壤质量的影响。结果表明:土壤食细菌线虫可提高生物土壤结皮下土壤脲酶、蔗糖酶、脱氢酶和碱性磷酸酶活性,且土壤酶活性随土壤食细菌线虫接种密度的增加呈现先升后降的规律,指示土壤食细菌线虫与微生物存在互利共生关系;此外,接种土壤食细菌线虫背景下,结皮类型也显著影响土壤酶的活性,藓类结皮下土壤酶的活性显著高于藻-地衣结皮(P<0.05),指示结皮发育有利于土壤食细菌线虫与微生物的互长模式。因此,在腾格里沙漠人工植被固沙区土壤食细菌线虫可提高生物土壤结皮下土壤酶的活性,指示土壤食细菌线虫可促进荒漠区土壤的修复进程,有利于荒漠生态系统的改良。

Soil bacterial-feeding nematodes act as important biological components in soil,which affect soil energy flow and material circulation.However,little was known on the function of soil bacterial-feeding nematodes in desert ecosystems.Sand dune soil under biocrusts in the artificial vegetation areas at the southeast edge of Tengger desert was studied to explore the effects of soil bacteria-feeding nematodes on soil in desert areas.Soil samples of 0-10 cm with cyanobacteria-lichen and moss crusts were collected,and inoculated bacterial-feeding nematodes following the density of 10,30,60,90,120 and 150 individuals in per gram of soil,respectively.Soils with no bacterial-feeding nematodes were as contrasts.The activities of soil urease,sucrase,dehydrogenase and alkaline phosphatase were examined to make sure the effects of bacterial-feeding nematodes on soil quality in desert areas.The results showed that soil bacterial-feeding nematodes increased the activities of soil urease,invertase,dehydrogenase and alkaline phosphatase under biocrusts,and soil enzyme activities increased first and then decreased with increasing the density of soil bacterial-feeding nematodes.The results indicated a mutually beneficial symbiosis between soil bacterial-feeding nematodes and microorganisms.In addition,crust types also significantly affected four studied enzyme activities following the inoculation of soil bacterial-feeding nematodes into soil.Moss crusts has significantly higher soil enzyme activities than that of cyanobacteria-lichen crusts(P<0.05),indicating that the development of crusts is beneficial to the mutual growth mode between bacterial-feeding nematodes and microorganisms.Therefore,soil bacterial-feeding nematodes could increase soil enzyme activities beneath biocrusts in the artificial vegetation area of the Tengger Desert,indicating that soil bacterial-feeding nematodes could promote the process of soil restoration in desert areas and they are beneficial to the improvement of desert ecosystems.