半干旱区丛枝菌根真菌复垦地生物结皮胞外酶活性及化学计量特征

Extracellular enzyme activity and stoichiometric characteristics of biological crust in mycorrhizal restoration area of western coal mining subsidence

丛枝菌根真菌(Arbuscular Mycorrhizal Fungi,AMF)对煤矿区生态恢复有长期促生效应,能直接影响生物结皮的生长发育,生态修复效应目前很少涉及生物结皮影响养分循环和胞外酶活性方面的报道。以大柳塔采煤沉陷微生物复垦示范基地修复11 a的对照(CK)区和AMF区为研究区域,选择2个区域里4种不同类型生物结皮:藻结皮、混生藻结皮(藻盖度>50%)、混生藓结皮(藓盖度>50%)、藓结皮为研究对象,分析不同类型生物结皮盖度、厚度,土壤、枯落物和林下植被的总有机碳(TOC质量分数)、全氮(TN)、全磷(TP)及β–1,4–葡萄糖苷酶(BG)、β–1,4–乙酰基氨基葡萄糖苷酶(NAG)、亮氨酸氨基肽酶(LAP)和碱性磷酸酶(AP)活性,研究土壤养分及环境因子对生物结皮胞外酶及养分限制的影响。CK区藻结皮盖度比藓结皮高31.3%,而AMF区表现出藓结皮盖度比藻结皮高27%,AMF区和CK区生物结皮的厚度均呈现藻结皮<混生藻结皮<混生藓结皮<藓结皮的趋势,且AMF区生物结皮厚度大于CK区,表明菌根复垦促进了西部采煤沉陷区生物结皮的发育。生物结皮层土壤有机碳(SOC)、TN、TP及胞外酶BG、NAG+LAP、AP活性较裸土均显著增加,藓结皮显著大于藻结皮,表明生物结皮演替加速表层土壤养分恢复及循环。AMF区藻结皮、混生藻结皮、混生藓结皮3种类型结皮SOC和TN质量分数及胞外酶BG、NAG+LAP、AP活性均显著高于CK区。结皮土壤微生物群落受到P限制。生物结皮土壤从藻结皮发育至藓结皮呈现出C/P、N/P逐渐增加趋势,但ABG/(A_(NAG)+A_(LAP))和A_(BG)/A_(AP)随结皮从藻结皮至藓结皮的发育降低(A为胞外酶活性)。RDA分析显示,生物结皮SOC、TN、TP质量分数与BG、NAG+LAP及AP活性存在正相关关系但与酶向量长度及角度呈负相关。AMF通过改善枯落物盖度、林下草本植被盖度及养分状况提升生物结皮养分含量及胞外酶活性,缓解P限制。

Arbuscular Mycorrhizal Fungi(AMF)can promote ecological restoration in coal mining areas for a long time,and can directly affect the growth and development of biological crusts,but the effects of biological crusts on nutrient cycling and extracellular enzyme activities are rarely reported.The control(CK)zone and AMF zone of Daliuta coal mining subsidence microbial reclamation demonstration base for 11 years were used as the study zones.Four different types of biological crust in two zones:algal crust,mixed algal crust(algal coverage>50%),mixed moss crust(moss coverage>50%),and moss crust were taken as the research objects.The coverage and thickness of different types of biological crust,total organic carbon(TOC),total nitrogen(TN),total phosphorus(TP)of soil,litter,and understory vegetation,and the activities ofβ–1,4–glucosylase(BG),β–1,4–acetyl glucosylase(NAG),leucine aminopeptidase(LAP)and alkaline phosphatase(AP)were taken as the analysis contents.The coverage of algae crust in CK zone was 31.3%higher than that of moss crust,and the coverage of moss crust in AMF zone was 27%higher than that of algae crust.The thickness of biological crust in AMF zone and CK zone showed the trend of algae crust<mixed algae crust<mixed moss crust<moss crust.The thickness of biological crust in AMF zone was greater than that in CK zone.It shows that mycorrhizal reclamation promotes the development of biological crust in coal mining subsidence area in western China.The soil organic carbon(SOC),TN,TP and the activities of extracellular enzymes BG,NAG+LAP and AP were significantly higher than those in bare soil,and the moss crust was significantly higher than that of algae crust.It shows that the succession of biological crust accelerates the recovery and circulation of nutrients in the surface soil.The SOC and TN contents and the activities of extracellular enzymes BG,NAG+LAP and AP in AMF zone were significantly higher than those in CK zone.The microbial community in crusted soil was limited by P.The biological crust showed a gradual increase trend of C/P and N/P from algae crust to moss crust,but ABG/(A_(NAG)+A_(LAP))and A_(BG)/A_(AP) decreased with the development of crust from algae crust to moss crust.RDA analysis showed that SOC,TN,TP were positively correlated with the activities of BG,NAG+LAP and AP,but negatively correlated with the length and Angle of the enzyme vector.AMF can improve the nutrient content and extracellular enzyme activity of biological crust,alleviate phosphorus limitation by improving litter coverage,herb vegetation coverage and nutrient status under forest.