封育措施下荒漠草原不同枯落物分解特征

以荒漠草原优势植物羊草(Leymus chinensis)、短花针茅(Stipa breviflora)及羊草+短花针茅(Leymus chinensis+Stipa breviflora)枯落物为研究对象,通过模拟试验,采用分解袋法,测定不同枯落物在分解过程中残留率的变化,分析枯落物元素释放规律及分解过程中对土壤性质的影响。结果表明:(1)在整个试验期内,不同枯落物残留率和质量损失率呈慢—快趋势,分解速率表现为羊草+短花针茅>短花针茅>羊草;试验区枯落物分解可以较好地拟合为Olson模型,不同枯落物分解50%和95%分别需要2.79~3.15,12.05~13.62年;(2)经过360天的分解,不同枯落物的全C、N、P均表现为释放的状态(NAI<100%),其中全C呈现波动释放的变化特征,释放比例为47.88%~54.54%;全N、全P呈释放—富集—释放的变化特征,其释放比例分别为36.34%~47.87%,57.08%~74.71%。(3)不同枯落物的分解均提高土壤有机C、N、P含量,均比初始值分别增加1.41~1.50,1.27~1.40,0.14~0.15 g/kg。研究结果为草地生态系统元素循环过程提供理论依据。

Decomposition Characteristics of Different Litters in the Desert Steppe Under Enclosure Measures

Withered Litters from Leymus chinensis, Stipa breviflora and Leymus chinensis + Stipa breviflora were taken as the research object. The decomposition bag method was used to measure the residual rates of different litters through a simulation experiment, and to analyze the release law of litter elements and the influence on soil properties during the decomposition process. The results showed that: (1) During the whole test period, the residual rates and mass loss rate sof different litters showed a slow-fast trend, and the decomposition rates showed Leymus chinensis + Stipa breviflora > Stipa breviflora > Leymus chinensis. The litter decomposition in the test area could be well fitted by Olson model. Decomposing 50% and 95% of different litters needed 2.79~3.15 and 12.05~13.62 years, respectively. (2) After 360 days of decomposition, the total C, N and P of different litters all showed the state of release (NAI < 100%), and the total C showed the characteristic of fluctuating release, with the release ratio ranging from 47.88% to 54.54%. Total N and P showed the characteristics of release-enrichment-release, with the release ratios of 36.34%~47.87% and 57.08%~74.71%, respectively. (3) Decomposition of different litters increased the contents of soil organic C, N and P, which increased by 1.41~1.50 g/kg, 1.27~1.40 g/kg and 0.14~0.15 g/kg respectively compared with the initial values. These research results could provide theoretical basis for the element circulation process of grassland ecosystem.