不同放牧干扰对滇西北高原泥炭沼泽土壤生态化学计量特征的影响

Effect of Difference Grazing Distributions on Soil Ecological Stoichiometric Characteristics in Peatland of Northwest Yunnan Plateau

为了阐明放牧过程对泥炭沼泽土壤化学计量特征的影响及机制,为放牧对湿地生态系统干扰及泥炭沼泽养分循环研究提供理论基础。以滇西北高原泥炭沼泽为研究对象,分析了土壤含水率、pH值、总有机碳(TOC)、总氮(TN)、总磷(TP)、铵态氮(NH+4-N)、硝态氮(NO-3-N)及土壤碳(C)、氮(N)、磷(P)生态化学计量特征,从而研究了放牧过程中藏猪翻拱(ZG)和牦牛践踏(JT)对泥炭沼泽土壤化学计量特征的影响。结果表明:放牧降低了土壤含水率、pH值、TN、TOC含量,增加了TP含量;ZG显著增加了NO-3-N含量。放牧降低了土壤养分化学计量,其中ZG和JT的C/P存在显著差异(p<0.05);放牧降低了微生物生物量碳氮比(MBC/MBN)及微生物生物量碳磷比(MBC/MBP),却提高了微生物生物量氮磷比(MBN/MBP),其中ZG对微生物生态化学计量的影响显著高于JT;放牧增加了生态酶化学计量。冗余分析显示TP、含水率、容重、NO-3-N、TOC是主要影响化学计量的环境因子。MBC/MBN,MBN/MBP均与对应的生态酶化学计量呈正相关,然而MBC/MBP呈相反趋势。C/N,C/P均与对应的生态酶化学计量呈正相关,然而N/P与对应的生态酶活性呈负相关。土壤养分化学计量变化影响了微生物生态化学计量以及生态酶化学计量。

In order to clarify the influence and mechanism of grazing process on the stoichiometric characteristics of peat swamp soil,provide theoretical basis for the research on disturbance of grazing to wetland ecosystem and nutrient cycling of peatland,a typical peatland was selected to study the effect of pig arching(ZG)and yak trampling(JT)on soil ecological stoichiometric characteristics in northwestern Yunnan plateau,and the contents of moisture,pH value,soil total organic carbon(TOC),total nitrogen(TN),total phosphorus(TP),ammonium(NH+4-N),nitrate(NO-3-N)and soil ecological stoichiometric characteristics were investigated.The results showed that livestock grazing reduced soil moisture,pH value,TN,TOC,but increased TP,the soil NO-3-N was increased by ZG,grazing reduced soil nutrient stoichiometry,and there was a significant difference in C/P between JT and ZG(p<0.05);grazing decreased MBC/MBN and MBC/MBP,but increased MBN/MBP;ZG had stronger effects on microbial ecological stoichiometry than JT;grazing increased soil ecoenzyme stoichiometry.Redundancy analysis showed that TP,moisture,bulk density,NO-3-N and TOC were primary environmental factors affecting soil ecological stoichiometry.The MBC/MBN and MBN/MBP were positively related to the ecological enzyme stoichiometry,while the MBC/MBP showed the opposite trend.N/P was negatively correlated with the ecological enzyme activity,the soil C/N and C/P were positively correlated with ecoenzyme stoichiometry.The changes of soil nutrient stoichiometry affected microbial ecological stoichiometry and ecoenzyme stoichiometry.