Response Characteristics Of Soil Microarthropod Community Structure In Marsh Of Northeast China To Warming

The Sanjiang plain is a concentrated distribution area of freshwater marshes in China.In recent years,the annual average temperature and the average temperature of growing season show a warming trend,which will continue in the next 40 years(2011 ～ 2050),under the background of global warming.Yet,little is known about the response characteristics of the soil microarthropods community structure to warming in this area.In order to investigate the responses of soil microarthropods community composition,diversity,vertical differentiation and trophic structure to warming under three kinds of water levels,we have carried out a research in marsh of the Sanjiang plain in China,using open-top chambers and stable isotope technology.In this study,1032 Collembola from 20 families,14 genera,20 species,and 243 Oribatida from 6 genera and 6 species were collected from natural marshes.There were 2224 Collembola of 20 species from 20 families,15 genera and 290 Oribatida from 7 species from 6 genera in the warming treatment.20 species of Collembola and 10 species of 1376 Oribatida were collected in marsh wetland,which was coordinated by warming and water level.Results showed that soil Collembola and Oribatida density in natural marshes was increased by warming treatment.As for Collembola,the number of dominant species and rare species increased,while that of common species decreased.For Oribatida,the number of common and rare species increased,and the dominant species decreased.Warming also reduced Collembola density in the marshes with 0 cm and-10 cm water levels,and increased Oribatida density in those marshes.The number of species of Collembola in the water level of 0 cm was significantly reduced,and the number of species of Oribatida in these two water levels was increased.In addition,warming significantly enhanced the evenness of soil Collembola in the water level of 0 cm in autumn,and decreased the evenness of soil Collembola in the water level of-10 cm,which had no obvious effect on spring and summer.In general,warming changed the community composition of soil microarthropod in marsh.It has a positive effect on Collembola density in natural marshes,but a negative effect on soil Collembola density in low water level marshes.The nitrogen stable isotope characteristics of 11 species of Collembola and 4 species of Oribatida in the Sanjiang Plain marsh were analyzed.Results indicate that warming increased the nitrogen stable isotope value range of Collembola,however decreased the nitrogen stable isotope value range of Oribatida,which may because the change of food source.In addition,warming reduced the trophic level of soil fauna in marsh,which was mainly manifested in the decrease of Banksinoma akhtyamovi from tertiary consumers to secondary consumers.In terms of the change of nutrient level,the response of Oribatida to warming was more sensitive than that of Collembola.The distribution of soil microarthropods in marsh showed that the three treatments of warming,decreasing water level and their interaction all had significant effects on soil Collembola and Oribatida.All three treatments encouraged more soil Collembola to move up.Warming and decreasing water level cause more soil Oribatida to move deeper,while the interaction between warming and decreasing water level causes soil Oribatida to move up.Warming decreases the surface aggregation of Oribatida.