Effects Of The Combined Stress And Bacterial-feeding Nematode On Functional Stability Of Soil Ecosystem

Due to the close relationship between the stability of soil ecological function and the sustainable development of human beings,maintaining and improving the stability of soil ecological function has been one of the central issues in soil ecology.As two main factors,including biotic and abiotic,can affect the stability of soil ecological function,many researchers have studied the abiotic factors that affect the stability of soil ecological function.Recently,abiotic factors affecting the stability of soil ecological function have been studied continuously.However,most of them have focused on the effect of single stress,leaving the effect of multiple stress on soil ecological function remains largely unknown.Because the soil ecosystem is always influenced by multiple environmental stress,it is necessary to carry on relevant experiment to do more in-depth discussion.As one of the most abundant and diverse soil fauna,soil nematodes play an important role in maintaining the stability of soil ecological function.Moreover,the variation of their community structure can reflect the environmental change,thus soil nematodes can be used to indicate the change in soil ecological function stability.We set up several types of stressor(copper,dry,heat and herbicide).Besides,we measured the decomposition degree of organic materials(grass powder and rice straw)and soil nematode community structure under the stressors to reflect the variation of soil ecological function stability.Firstly,we conducted a study on red soil to find out the optimum soil volume for nematode extraction.Secondly,we studied the effect of single stress(dry,heat and herbicide)and combined stress(dry+heat and dry + heat + herbicide)on the stability of soil ecological function under three different agricultural management practices(conventional flooded,uncovered cultivation and film mulching cultivation).Finally,based on nematode enrichment in situ,we designed three nematode addition treatments(a large amount of nematode,a small amount of nematode and small amount of nematode but inoculate soil microbial community)to study the effect of bacterial-feeding nematode on the stability of soil ecological function under copper or heat stress.Our results showed that:The best condition of nematode extraction was 150g of soil weight and 1.00cm of soil thickness in the heavy red soil.There’s no significant difference on the effect of stress on the activity of soil microorganisms and nematodes,soil nutrient content and soil ecological function stability compared with control under three agricultural management practices.Stress resulted in a consistent response on soil nutrients and soil organisms.Combined stress induced more severe damage than single stress,especially in soil nematode abundance.Soil respiration and resilience were observed similar trend in the condition of a persistent copper stress or an instantaneous heat stress,with significantly higher value in the treatment of large amount of nematode than the treatment of small amount of nematode.These indicated that the existing of bacterial-feeding nematode could improve soil resilience capability.Our study demonstrated the effect of biotic factors and abiotic factors on soil ecological function stability,which is the effect of stress condition on organic material decomposition and soil nematode community structure.Our study showed that combined stress induced more severe damage than single stress;soil nematode was a good indicator in indicating the variation of soil ecological function stability;the more number of bacterial-feeding nematode added into the soil,the more help would it favored the soil resilience.