旱作农田改为水浇地对沙质土壤节肢动物群落的影响

Effects of dry farmlands conversion to irrigation farmlands on soil arthropod community

为了了解旱作农田改作水浇地对沙质土壤节肢动物群落的影响,2008-2009年在科尔沁沙地奈曼旗调查比较了灌溉农田与旱作农田土壤节肢动物群落结构和多样性的差异,分析了其成因。研究结果表明:1)旱作农田改为水浇地后,土壤节肢动物群落组成和种群密度分别由4目12科和35.2只/m2增加到5目15科和83.2只/m2,Shannon多样性、均匀度和优势度指数也分别增加了4.2%、16.9%和11.8%;2)旱作农田改为水浇地后,有5个类群因不适应农田灌溉而消失,有8个新的类群侵入,优势类群由拟步甲科更替为蚁科,亚优势类群由叩甲科和蚁科更替为皿蛛科和蚁甲科,群落发生演替;3)群落中捕食性和杂食性类群比重分别由20.8%和15.4%增至40.0%和26.7%,植食性类群比重由30.8%降至20.0%,群落中捕食性和杂食性密度比重分别由18.2%和18.2%增至30.8%和51.9%,植食性动物密度比重由54.5%降至9.6%;4)土壤动物类群数、密度、多样性和均匀度指数均与土壤机械组成、土壤水分、有机质、全氮、全磷含量呈正相关,与土壤温度和pH值呈负相关。这些结果说明,旱作农田改为水浇地可以增加土壤节肢动物群落多样性和种群数量,改变群落功能群结构,降低土壤节肢动物对作物危害的风险,其作用机制主要源于灌溉可以明显改善土壤质地、水热条件和土壤养分状况,特别是土壤有机质和pH的变化。

Diversity and composition of soil arthropod community in dry farmlands and irrigation farmlands in Horqin Sand Land were surveyed to understand the effect of dry farmland conversion to irrigation farmlands on soil arthropod community.The results showed that.（1） When dry farmland was changed to irrigation farmlands,group composition and individual density in soil arthropod community increased from 4 orders 12 families and 35.2 ind.m-2to 5 orders 15 families and 83.2 ind.m-2,Shannon diversity,evenness and dominant index increased by 4.2%,16.9% and 11.8%,respectively.（2） In farmland conversion process,individual density increased in 3 groups,and no changed in 3 groups,and decreased in 1 group,5 groups disappeared and 8 new groups invaded.Dominant group Tenebrionidae and sub-dominant group Elateridae and Anthicidae were replaced by Anthicidae,Linyphiidae and Pselaphidae,respectively.（3） Group proportion of predator and omnivore in the community increased from 20.8% and 15.4% to 40.0% and 26.7%,proportion of phytozoon decreased from 30.8% to 20.0%,density proportion of predator and omnivore increased from 18.2% and 18.2% to 30.8% and 51.9%,proportion of phytozoon decreased from 54.5% to 9.6%.（4） Group number,individual density,diversity and evenness had a positive correlation with soil texture,soil moisture,organic matter,total N and P,and a negative correlation with soil temperature and pH.These results suggested that dry farmland was changed to irrigation farmlands could increase group diversity and individual density of soil arthropod community and improve function structure of the community,which could decrease risk of soil arthropod damage to crop and facilitate succession of the community.It is main mechanism to cause changes of soil arthropod community that irrigation could improve soil texture,soil water and heat condition and soil nutrients,specially soil organic matter and pH.