荒漠草原4种典型植物群落枯落物分解速率及影响因素

测定荒漠草原甘草、赖草、蒙古冰草以及黑沙蒿等植物群落枯落物分解过程中质量损失量分析荒漠草原枯落物分解速,同时通过枯落物自身化学成份、含水率的测定,结合气候因子进行偏相关分析,探讨荒漠草原枯落物分解的影响因素。结果表明:荒漠草原4种植物群落枯落物的质量累积损失率随分解时间的延长而增加,但枯落物分解的质量损失量与时间并不呈线性相关;4种群落枯落物质量损失量大小依次均为:甘草群落赖草群落蒙古冰草群落黑沙蒿群落;荒漠草原枯落物分解采用单指数衰减的Olson模型拟合效果较好,4种植物群落中甘草群落枯落物分解最快,黑沙蒿群落分解最慢;蒙古冰草、赖草和甘草群落枯落物中N、P、K的含量显著高于黑沙蒿群落,但是C、木质素、纤维素、C/N、木质素/N和纤维素/N值则显著低于黑沙蒿群落枯落物,蒙古冰草群落、甘草群落、赖草群落和黑沙蒿群落4种群落枯落物分解速率(k)与枯落物初始N、P、K含量均呈显著正相关;偏相关分析表明,4种植物群落枯落物分解速率与降雨量、枯落物自身含水量的偏相关系数达显著水平,其余因子偏相关系数均未达显著水平。结合上述研究可以确定荒漠草原枯落物分解50%所需时间为2—5a,分解95%需8—24a。

Litter decomposition rates and influencing factors of four typical plant communities in desert steppe

Litter is the important components of grassland ecosystem, and plays an important role in grassland, influencing ecosystem structure, process and functioning. Litter accumulation can change the nutrient availability and modify local physical environmental conditions, and litter of grassland has gradually become one of the important issues in grassland ecology, but the factors related to the decomposition litter and litter decomposition rates in desert steppe is still unknown. In this study, four typical plant litters of desert steppe, Glycyrrhiza uralensis, Leymus secalinus, Agropyron crisatum and Artemisia desertorum communities were selected in Yanchi Country of Ningxia, and the loss rate of litter mass, the chemical composition, the water content of four typical plant communities were measured, and climatic factors and their partial correlations were analyzed, and statistics and numerical taxonomy methods were used to identify the effects of litter accumulation. The results showed that the loss rate of litter mass was increased with decomposition time. However, the relationship between the loss rate of litter mass and decomposition time was not linear correlation. The loss rate of litter mass of four typical plant communities was Glycyrrhiza uralensis community > Leymus secalinus community > Agropyron crisatum community > Artemisia desertorum community. The litter decomposition rates of desert steppe was best represented by the he Olson model of single exponential decay, and the litter decomposition rate of Glycyrrhiza uralensis was the fastest, while the Artemisia desertorum was the slowest. The contents of N,P,K of litters of Agropyron crisatum, Leymus secalinus and Glycyrrhiza uralensis communities were significantly higher than Artemisia desertorum community, but contents of C, lignin, cellulose, and rates of C:N and lignin:N and cellulose:N were significantly lower than litter of Artemisia desertorum community. The decomposition rates of four plant communities was positively correlated with the initial contents of N,P,K in litters,. Partial correlation analysis results showed the decomposition rates of four plant communities was significantly correlated with rainfall and the water content of litter. It was concluded that litter decomposition was complex physical and chemical and biological processes, which Influenced by many factors, and plant species was an major factor decisioned the rate of decomposition. The contents of 50% of litters decomposed in desert steppe was about 2-5 years, while 95% was about 8-24 years, which could provide scientific basis for the response and adaptation mechanism of grassland on the environmental factors and adaptation strategy.