荒漠草原区土壤动物分解作用对土壤C、N、P、K含量分布的影响

Effects of Soil Arthropods Decomposition on Soil C、N、P、K Content in Desert Steppe

选择半干旱(宁夏盐池)、干旱(内蒙古乌拉特后旗)荒漠草原区为研究样地,以牛枝子枯落物为研究对象,采用网孔分解袋法研究土壤动物分解功能对枯落物C、N、P、K分布的影响,结合枯落物分解过程中土壤有机碳(SOC)、全氮(TN)、全磷(TP)、全钾(TK)含量分布特征,阐明土壤动物分解作用对土壤营养元素含量分布的影响规律。结果表明:(1)共捕获土壤动物226只,隶属14科(属)。土壤动物个体数表现为盐池地区均高于乌拉特地区,而类群数差异较小,仅在乌拉特地区灌丛高于裸地。土壤动物Simpson指数、Shannon指数和Margalef指数在不同生境下均无显著差异,Pielou指数在裸地生境下表现为乌拉特地区显著高于盐池地区。(2)不同网孔分解袋中枯落物养分元素均处于不同程度的释放状态。其中枯落物C、N元素累积系数在盐池地区表现为2 mm网孔显著低于0.01 mm网孔,在乌拉特地区表现为2 mm网孔显著高于0.01 mm网孔;枯落物P、K元素累积系数分别在乌拉特地区和盐池地区表现为2 mm网孔显著高于0.01 mm网孔,且土壤动物对盐池枯落物C、N、P、K元素释放均表现为正效应;对乌拉特枯落物C、N元素释放表现为灌丛为负效应,裸地为正效应,P、K元素释放表现为灌丛为正效应,裸地为负效应。(3)土壤动物对TN、TK增量受灌丛内外微生境差异的影响,表现为乌拉特灌丛显著高于裸地。且土壤动物对土壤SOC增量均为正效应;对TK、TP增量在灌丛为正效应,在裸地为负效应;对TN增量在不同地区不同微生境下效应不同。(4)Pearson相关分析和RDA分析表明,土壤动物多样性分布和土壤理化性质显著影响枯落物养分释放。综合分析表明,在半干旱区土壤动物加速枯落物养分释放和土壤SOC积累,而土壤TP、TN、和TK的积累受灌丛微生境的影响;在干旱区土壤动物对枯落物C、N元素和P、K元素释放在灌丛和裸地微生境作用相反,且土壤动物加速灌丛、减缓裸地土壤养分的输入。土壤动物增强枯落物养分元素在生态系统中的流动性,改变枯落物养分输入土壤的直接关系,且土壤对枯落物的分解具有一定的调控作用,其中土壤TK起主要作用。

The semi-arid(Yanchi,Ningxia)and arid(Urad Rear Banner,Inner Mongolia)desert steppe areas were selected as the research sites,and the Lespedeza potaninii litter was taken as the research object.The mesh decomposition bag method was used to study the effects of soil arthropod decomposition function on the distribution of litter C,N,P and K.Combined with the distribution characteristics of soil organic carbon(SOC),total nitrogen(TN),total phosphorus(TP)and total potassium(TK)in the process of litter decomposition,the influence of soil arthropod decomposition on the distribution of soil nutrient elements was clarified.The results showed:(1)A total of 226 soil arthropods belonging to 14 families(genera)were captured.The individual density of soil arthropods in Yanchi was higher than that in Urat,while there was little difference in species richness,which was higher in shrub canopy than bare soil only in Urat.The Simpson,Shannon and Margalef index of soil arthropods showed no significant differences in different habitats,while Pielou index in bare soil was significantly higher in Urat than in Yanchi.(2)The nutrient elements of litter in different mesh decomposition bags were released in different degrees.The cumulative coefficients of C and N in litter were significantly lower in the 2 mm mesh than in the 0.01 mm mesh in Yanchi,and significantly higher in the 2 mm mesh than in the 0.01 mm mesh in Urat.The accumulation coefficients of P and K in litter were significantly higher in the 2 mm mesh than in the 0.01 mm mesh in Urat and Yanchi,respectively,and soil arthropods showed positive effects on the release of C,N,P and K from litter in Yanchi;the release of C and N from litter in Urat showed a negative effect in shrub canopy and a positive effect in bare soil,the release of P and K from litter showed a positive effect in shrub canopy and a negative effect in bare soil.(3)The increment of TN and TK by soil arthropods was affected by the difference of microhabitats between inner and outer shrub,which showed that the increment of TN and TK in Urat shrub canopy was significantly higher than that of bare soil.Soil arthropods had positive effects on soil SOC increment;the increments of TK and TP had positive effect in shrub canopy and negative effect in bare soil;the effect on TN increment was different in different regions and different microhabitats.(4)Pearson correlation analysis and RDA analysis showed that the distribution of soil arthropods diversity and soil physical and chemical properties significantly affected the nutrient release of litter.Comprehensive analysis showed that soil arthropods accelerated litter nutrient release and soil SOC accumulation in semi-arid areas,while the accumulation of soil TP,TN,and TK in soil was affected by shrub microhabitats.In arid areas,soil arthropods had opposite effects on litter C,N and P,K release in shrub canopy and bare soil microhabitats,and soil arthropods accelerated the nutrients input in shrub canopy and slowed down the nutrients input in bare soil.Soil arthropods enhanced the mobility of litter nutrient elements in the ecosystem,changed the direct relationship between litter nutrient input to soil,and soil had a certain regulatory effect on litter decomposition,which soil TK played a major role.