| An investigation on plants litter of Leymus secalinus,Lespedeza bicolor and their mixture was carried on by the method of litterbag sampling in desertified steppe of Ningxia.The objective of the present study was to probe into three content:(1)The characteristics of the loss of mass of plants in different treatments were investigated,in order to clarify the change of litter decomposition rate.(2)The residual rates of P,K,N,lignin and acid detergent fibers in different treatment plants were measured,to analyze the release dynamics of nutrient elements in litter.(3)The number of soil animals were counted,and the contribution rate of soil animals to litter quality loss and nutrient elements release were studied in the litter decomposition process.On the one hand,the results were important for understanding the relationship between above-ground and under-ground ecosystems.On the other hand,it provided a basis of soil animal ecology for grassland ecosystem management,restoration and protection in desertified steppe.The main results obtained:(1)The litter decomposition rate of different treatments plants was found to follow an order of mixed>L.secalinus>L.bicolor in the 4-mm-mesh and 0.01-mm-mesh litterbags.However that in the 2mm-mesh litterbags was found to follow an order of mixed>L.bicolor>L.secalinus.At 70 d,140 d and 210 d,the plants litter decomposition rate in 4-mm-mesh and at 70 d,210 d and 280 d in 2-mm-mesh litterbag was found mixture and L.bicolor significantly higher than L.secalinus.The decomposition rate of plants in 570 d in 4-mm-mesh and 640 d in 2-mm-mesh was found mixture and L.secalinus significantly higher than L.bicolor.At 210 d,the plants litter decomposition rate in 0.01-mm-mesh was found mixture and L.bicolor significantly higher than L.secalinus.(2)At the sampling time of 640 days,the residual rate of plants litter P was found to follow an order of L.bicolor>L.secalinus>mixture in 4-mm-mesh,whereas in 2-mm-mesh and in 0.01-mm-mesh was found to follow an order of L.secalinus>L.bicolor>mixture.The residual rate of plants litter K was found to follow an order of L.bicolor>L.secalinus>mixture in 4-mm-mesh and in 2-mm-mesh,whereas in 0.01mm-mesh was found to follow an order of L.bicolor>mixture>L.secalinus.The residual rate of plants litter N was found to follow an order of L.secalinus>mixture>L.bicolor in 4-mm-mesh and in 0.01-mmmesh,whereas in 2-mm-mesh was found to follow an order of L.secalinus>L.bicolor>mixture,The residual rate of plants litter acid detergent fibers was found to follow an order of L.bicolor>L.secalinus>mixture in 4-mm-mesh and in 0.01-mm-mesh,whereas in 2-mm-mesh was found to follow an order of L.bicolor>mixture>L.secalinus.The residual rate of plants litter ligion was found to follow an order of mixture>L.bicolor>L.secalinus in 4-mm-mesh and in 0.01-mm-mesh,whereas in 2-mm-mesh was found to follow an order of L.bicolor>L.secalinus>mixture.Moreover,the residual rate of plants litter N element,acid detergent fiber and lignin in three kinds of mesh litterbags were significantly different in every time periods,whereas the residual rate of P element of litter was only different in 2mm-mesh and 0.01-mm-mesh in every time periods,and the residual rate of K element was significantly different only in the 2-mm-mesh in every time periods.(3)The contribution rate of soil animals to litter decomposition of different treatments plants was expressed medium and small soil animals and microorganisms(2-mm-mesh)>large,medium,small soil animals and microorganisms(4-mm-mesh).The contribution rate of soil animals to the release of P element in different treatments plants litter was as follow:large,medium,small soil animals and microorganisms(4-mm-mesh)>medium and small soil animals and microorganisms(2-mm-mesh).The contribution rate of soil animals to K element release was less than 0.The contribution rate of soil animals to the release of N element in different treatments plants litter was as follow:medium and small soil animals and microorganisms(2-mm-mesh)>large,medium and small soil animals and microorganisms(4-mm-mesh).It was concluded that the number of soil animals based on litterbag method of different mesh affected the decomposition rate and nutrient release of plants.In the three kinds of mesh litterbags,the mixed litter decomposition was faster than the single plants litter.Moreover,the mixed litter releases P and K elements and the acidic detergent fiber were higher than the single plants litter,while the N element released by the L.bicolor litter were higher than the other two treatments plants litter,and the lignin released by the L.secalinus were higher than the other two treatments plants litter.Soil animals showed a positive effect on the mass of loss of litter quality.However,soil animals had different effects on the release of P,K and N elements. |
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