氮磷添加对黄土旱塬农田土壤线虫群落及能量结构的影响OA北大核心CHSSCDCSTPCD

To investigate the effects of nitrogen(N)and phosphorus(P)additions on the soil nematode community structure and energy flow within the micro food web in dryland farmland ecosystems of Loess Plateau,this study focused on the long-term application of N and P fertilizers at Changwu Agricultural Ecology Experimental Station of the Chinese Academy of Sciences.Six treatments were selected,including no fertilizer application(CK),N addition(N12,N24),P addition(P12,P24),and NP addition(N12 P12).Soil physicochemical properties were measured,nematodes were isolated utilizing the shallow disc method,subsequent analysis encompassed the evaluation of nematode trophic taxa structure and life history traits.Additionally,the computation of nematode ecological indices,metabolic footprints,and internal energy flow within the food web were calculated.The results demonstrated that the proportion of plant parasitic nematodes(Pp)was significantly higher in different treated soils than other taxa(50.7%—66.4%).Furthermore,the proportion of nematode taxa with a life history of cp2 was also significantly higher than the other taxa(68.1%—84.0%).The highest nematode abundance was recorded in P12 treatment with 1147 ind./100 g of dry soil followed by P24 treatment with 1100 ind./100 g of dry soil.Compared to the CK treatment,two P addition treatments significantly increased the Shannon diversity index(H),enhancing the metabolic footprints of fungivorous and predatory-omnivorous nematodes.This resulted in a higher energy flux within the micro-food web,indicating an increased energy flow.The remaining treatments did not exhibit any significant effects on nematode abundance and metabolic footprints.In comparison with the N24 treatment,the N12 treatment showed a significant increase in the H of the nematode community,as well as the evenness index(J)and richness index(SR).Furthermore,the N12 P12 treatment led to an increase in the number of nematodes in the cp4-5 category and significantly improved the structural index(SI).The redundancy analysis revealed that the total phosphorus and available phosphorus contents in the soil were the primary environmental factors influencing the abundance and metabolic footprints of nematodes.In summary,the moderate N addition enhances soil nematode community diversity and structural stability,while excessive N addition counteracts these beneficial effects.P addition positively influences both nematode communities and metabolic footprints,leading to an increase in energy flux within the soil micro food web.The NP addition creates a suitable habitat for soil nematodes.These findings provide a scientific basis for fertilizer management practices in agricultural soils of loess regions.