四川米仓山水青冈天然林下不同植物群落的土壤酶活性及化学计量特征

Soil Enzyme Activities and Stoichiometric Characteristics of Different Plant Communities under Natural Fagus Forest in Micang Mountain Nature Reserve,Sichuan

研究了四川米仓山自然保护区的水青冈(Fagus)天然林林下野扇花(Sarcococca ruscifolia)和箭竹(Fargesia spathacea)群落不同土壤(h)深度(0<h≤10 cm、10 cm<h≤20 cm)的酶活性、化学计量特征及其主要环境影响因子。研究结果表明:(1)在林下不同植物群落中,全氮(TN)含量表现为无植物群落高于有植物群落;在10 cm<h≤20 cm的土壤深度下,土壤全碳(TC)、碱解氮(SAN)含量表现为野扇花群落最高。(2)野扇花群落的土壤酶活性(酸性磷酸酶(AP)、1,4-β-N-乙酰葡糖胺糖苷酶(NAG))显著高于无植物群落和箭竹群落,β-葡萄糖苷酶(BG)、亮氨酸氨基肽酶(LAP)活性表现为箭竹群落最高,多酚氧化酶(PPO)、过氧化物酶(POD)活性表现为有植物群落显著高于无植物群落。(3)BG、LAP、PPO和POD这4种土壤酶活性与土壤pH呈显著正相关,土壤酶活性(除纤维二糖水解酶(CBH))均与土壤含水量呈显著正相关。冗余分析(RDA)结果显示,土壤含水量、SAN、TC含量分别解释了土壤酶活性及其化学计量特征变异的51.4%、40.5%、37.7%。(4)在3种不同植物群落下,向量角度(VA)均大于45°,表明3种不同植物群落下土壤微生物更易受到磷元素的限制。林下不同植物群落能影响土壤理化性质及土壤酶活性,土壤含水量、SAN和TC含量对土壤酶活性及其化学计量特征起主要调控作用。

In this study,the soil enzyme activities,stoichiometric characteristics and major environmental factors of Sarcococca ruscifolia and Fargesia spathacea communities at different depths(0<h≤10 cm,10 cm<h≤20 cm) were examined in the natural Fagus forest in Micang Mountain Nature Reserve,Sichuan.The results showed that:(1)In different understory plant communities,the total nitrogen(TN) content in plantless community was higher than that in plant community soil.At the soil depth of 10 cm<h≤20 cm,the contents of total carbon(TC) and soil available nitrogen(SAN) were the highest in the S.ruscifolia community.(2)The soil enzyme activities(acid phosphatase(AP),1,4-β-N-acetylglucosaminidase(NAG)) in the S.ruscifolia community were significantly higher than those in the no plant community and the F.spathacea community,and the activities of β-glucosidase(BG) and leucine aminopeptidase(LAP) were the highest in the F.spathacea community.The activities of polyphenol oxidase(PPO) and peroxidase(POD) in plant community were significantly higher than those in no plant community.(3)Soil enzyme activities of BG,LAP,PPO and POD were significantly positively correlated with soil pH,and soil enzyme activities(except cellobiohydrolase(CBH)) were significantly positively correlated with soil moisture content.The results of redundancy analysis(RDA) showed that soil moisture content,SAN and TC content explained 51.4%,40.5% and 37.7% of the variation of soil enzyme activity and its stoichiometric characteristics,respectively.(4)The vector angle(VA) was greater than 45°,suggesting that soil microorganisms were more susceptible to phosphorus restriction.The results indicated that different understory plant communities could affect soil physical and chemical properties and soil enzyme activities and their stoichiometric characteristics were mainly regulated by soil moisture content,SAN and TC content.