草地开垦对土壤动物多样性与功能群结构的影响

Effect of Cultivation of Sandy Grassland on Soil Arthropod Diversity and Trophic Structure in Agro-pasture Transition Zone

在中国科学院奈曼沙漠化研究站附近,选择耕作10年和20年农田为研究对象,以周围封育草地为对照,采用手拣法调查了不同类型样地土壤节肢动物群落组成与生物量,并依据食性差异对土壤节肢动物功能群进行了划分,旨在分析草地开垦活动及耕作时间对土壤动物群落结构的影响。研究结果表明,(1)草地开垦降低了土壤节肢动物个体数、丰富度、多样性和生物量,尤其对个体数与丰富度的影响较大(p<0.05),而农田耕作时间对土壤节肢动物群落多样性与生物量的影响较小(p>0.05);(2)草地开垦降低捕食性和植食性动物类群的个体数和丰富度,尤其对捕食性类群的个体数影响较大(p<0.05),而农田耕作时间产生的影响较小(p>0.05);(3)捕食性类群生物量表现为草地和耕作10年农田显著高于耕作20年农田(p<0.05),而草地开垦与耕作时间对植食性类群生物量的影响相对较小(p>0.05);(4)基于个体数、丰富度和生物量的不同类型样地间功能群营养级关系(捕食性:植食性)均无显著差异性(p>0.05);(5)草地开垦对土壤节肢动物多样性和功能群数量特征产生负向作用,而农田耕作时间对土壤节肢动物多样性的影响较小,草地开垦与耕作时间对功能群营养级关系影响相对较小,而耕作时间对捕食性类群生物量分布的影响较大。

At the Naiman Desertification Research Station,CAS,the cultivated croplands for 10and20 years were selected as the experimental sites,with the adjacent fenced grassland as a control in order to probe into the effect of the cultivation of sandy grassland on taxonomical and trophic structure of soil arthropods.The results showed that the density,taxa richness,diversity index and biomass of soil arthropods all tended to decline with the conversion of sandy grassland to agriculture.The density and taxa richness were pronounced by the conversion,suggesting the significantly higher values in the sandy grassland compared with the agriculture（p〈0.05）,regardless of cultivation time.Meanwhile,the density and taxa richness of predators and herbivores both tended to decline with the conversion of sandy grassland to agriculture,where the density of predators was significantly higher in the sandy grassland compared with the agriculture（p〈0.05）,regardless of cultivation time.However,the predator biomass indicated different pattern from herbivore biomass,suggesting significantly higher predator biomass in sandy grassland and10-year cultivated cropland compared with the 20-year cultivated cropland（p〈0.05）.The predator-prey interactions based on the density,richness and biomass was found to indicate no significant differences between the three treatment sites（p〉0.05）.It was concluded that the cultivation of sandy grassland indicated a negative impact on the diversity and trophic indices of soil arthropods,where the cultivation time showed little effect on the diversity indices.The predator-prey interaction was not affected by the cultivation,also with time,whereas a marked effect of cultivation time was found on the predator biomass.