Response Of Soil Nematode To Nitrogen Compounds Addition In Erguna Grassland,Inner Mongolia

With the development of the industrial revolution,the influence of human activities on the earth's environment is more and more serious.Anthropogenic activities such as fossil fuel combustion and high-intensity agriculture have increased the inputs of nitrogen oxides in the atmosphere far above natural,biogenic inputs.Input of reactive nitrogen from the atmosphere to the biosphere both as gases,dry deposition and in precipitation as wet deposition will result in N eutrophication and acidification of terrestrial ecosystem.Effects of nitrogen deposition on aboveground plant community have been widely reported,nevertheless,studies on response of soil biodiversity to N deposition and the underlying mechanism are rare.As the decomposer of soil ecosystem,soil animals play important roles in nutrient mineralization and other ecological processors of soil ecosystem.To soil nematodes are the most abundant multicellular organism on the earth.Soil nematode is sensitive to environmental disturbance and often used as indication organisms in soil ecology.We conducted a nitrogen compounds addition experiment in Erguna grassland,Inner Mongolia to manipulate natural nitrogen deposition and investigate the soil nematode community response.Not only does,but also the form of N make a difference in nitrogen deposition effects on ecosystem.We added 5 N compounds in our experiment which is more natural than add only one N compound.Effects of nitrogen addition on soil nematodes are different among various compounds.In general,nitrogen addition increased soil nematode abundance but decreased soil nematode diversity.Which means nitrogen addition leads to the loss of soil nematodes species.N addition also reduced soil nematode maturity(maturity index,MI)and enhanced dominance(dominance index,DOM)which shows large amounts of nitrogen input leads to soil nematode community degradation.Effects of nitrogen addition on soil nematode functional groups are different: Increased bacterivores and fungivores nematodes was found after nitrogen addition,on the contrary,N addition decreased plant parasites,omnivores and camivores nematode.Nitrogen addition reduced the proportion of fungivores and bacterivores nematode(F/B),which showed that nitrogen addition lead to a bacterial dominant energy and nutrient cycling channel.Our research has important implications on understanding soil biodiversity responses to future global nitrogen deposition.