Study On The Fall-litter Of The Dominant Plant Community In Desert Area

Litter is an important part of ecosystem. It plays a very important role in the maintenance of the structure and function of ecosystem, and it is also useful to promote the nutrient cycling and soil fertility of ecosystem. In recent years, with the change of global climate, litter is increasingly concerned in the role of carbon and nitrogen cycling.This paper was doing the research on the litter production, nutrient content, nutrient return, the decomposition rate and the trend of nutrient dynamics of three desert plants in the Ebinur Lake Wetland Nature Reserve Area of Xinjiang. In order to reveal the progresses of nutrient cycling of litter in the Desert ecosystems of arid areas, and provide a useful case for the litter of desert plant.By system research to the litter Characteristics of Populus, Tamarix and Haloxylon for one year, get the following conclusions:(1) There are significant differences in litter production in the three different desert plant types. the litter production in the three plant communities decreased in the order of Tamarix ramosissima(1942.74 kg/hm²)>Populus euphratica(832.83 kg/hm²)>Haloxylon ammodendron(74.34kg/hm²).(2) The litter throughout the year appeared an obvious trend of single-peak curve in the three desert plant types. In October and November, the input amount of litter accounted for 42.4%～80.7% of the annual total amount of litter production in the three desert plants.(3) The concentration of C was the highest one in the main nutrient of litter of three desert plants, the concentration of N was the second, and P was the lowest one. The sequence of annual total nutrient return was: C(782.76 kg·hm^-2)>N(20.46 kg·hm^-2)>P(3.56 kg·hm^-2). And for the nutrient use efficiency (NUE) of plants, the three plants in the four seasons showed that the NUE of P was the highest one, the NUE of N was the second, and the NUE of C was the lowest one.(4) Generally speaking, the decomposition of leaf litter of the three desert plants were very slowly. After one year decomposing, the weightlessness ratio of leaf litter in Populus, Tamarix and Haloxylon communities were: 12.23%, 17.67% and 7.67%. According to the Olson Model, the 95% declining of leaf litter of the three plants were: 32.6a, 19.4a and 44.7a.(5) The change of major nutrient content was significantly different of the leaf litter of three plants in the decomposition process. After one year decomposing, the N, P and Lignin in the leaf of Populus showed a net release state (NAI<100%), the organic C was manifested in the mode of accumulation-release, and the Cellulose showed a net accumulation state (NAI>100%); The N and P in the leaf of Tamarix showed a net release stste (NAI<100%), the organic C and Cellulose showed a net accumulation state (NAI>100%), and the lignin showed a accumulation-release state; The N and Cellulose in the leaf litter of Haloxylon showed a net release state (NAI<100%), the P and Lignin showed a release-accumulation state, and the organic C showed a accumulation-release state.(6) The correlation between C/N,C/P,N/P,Linnin/N and residual rate of dry matters are significant in the decomposition process of the leaf litter of three plants. Therefore, it shows that each ratio can be regarded as a good index judging the decomposition of leaflitters.(7) In the flooding experiment, the sequence of water holding capacity of leaf litter in the three plants was: Tamarix>Populus>Haloxylon; the sequence of water holding rate of leaf litter in the three plants was: Populus>Tamarix>Haloxylon; the order of water-absorption rate of leaf litter was Populus>Tamarix>Haloxylon. The water-holding capacity and water-holding rate of the litters changed logarithmically with soaking time while the water-absorption rate assumed a power function.