Decomposition Characteristics Of6Typical Plant Litters In The South Area Grassland Of Ningxia

Take the classical plants of Chinese loess plateau as the topic, according to the fieldsimulation and laboratory cultivation, to study the litter decompose transformation of soilorganic matter, total nitrogen, phosphorous, lignin, cellulose, C/N, C/P, lignin/N andcellulose/N, and the relationship between the substrate quality and decomposition rate. Inorder to reveal the characteristics of classical plant decomposition, explore the sourcecirculation and self-fertilizing mechanism under degraded ecology system. The conclusionswere as followed:(1) The concentration of total nitrogen and N/P ratio in Caragana korshinskii-Kom litterwere greatest, the ratio of C/N, C/P, lignin/N, cellulose/N were smallest. For the litter ofCaragana korshinskii-Kom, Artemisia giraldii Pamp and Artemisia mongolicus, the contentof lignin and cellulose in leaf and stem were higher than root. They have same distribution oflignin/N and cellulose/N among the different organs, the order was: root>steam>leaf. The rootof Artemisia giraldii Pamp has the highest lignin (56.30g/kg), the leaf of Caraganakorshinskii-Kom has the lowest one (22.25g/kg). However, the lignin/N and cellulose/N ofStipa bungeana Trin and Agropyron cristatum Gaertu in root were higher than in steam andleaf.(2) The variation tendency of litter decomposition rate were different, the rate ofArtemisia giraldii Pamp and Agropyron cristatum Gaertu root in the last90days was accountfor53and115%than former90days. There were no significant different between Thymusmongolicus, Stipa bungeana Trin, Agropyron cristatum Gaertu Caragana korshinskii-Komroot. The rates of Agropyron cristatum Gaertu were4-8times larger than Thymus mongolicusand Stipa bungeana Trin. As decomposition process going, the concentration of organiccarbon and nitrogen were gradually decreased, the total phosphorus was changed as unimodalcurve.(3) During the cultivation in laboratory, as time processed, litter nitrogen and lignin wereincreasing slowly, the content of Caragana korshinskii-Kom and Artemisia mongolicus inoriginal litter were occupied130and138than later one. The phosphorus was deceased firstand then kept stable. The cellulose concentration was deceased.(4)The decomposition rates of laboratory cultivation were higher than field simulation. Favorite moisture and temperature was benefit for litter decomposition. The condition ofhydrothermal was the factor that made the difference between two process modes. In fieldsimulation, the decomposed litter nitrogen and phosphorus were account for30-80%and7-28%than original. They were occupied130-383%and145-217%in laboratory cultivationmode. It is result of the effect of leaching that made the concentration of carbon and nitrogenwith different change. However, the lignin and cellulose in two treatment modes have thesame tendency.(5) The litter decomposition rate was significant related with original nitrogen content inpositive way (field simulation mode). There was no significant difference between litterdecomposition rate and soil moisture and temperature. In laboratory cultivation mode, thelitter decomposition rate was positively related with original nitrogen, C/N rate, andnegatively correlated with cellulose and cellulose/N.