Yang Yu-Hai, Zheng Lu, Duan Yong-Zhao
State Key Laboratory of Desert and Oasis Ecology, Urumqi 830011, China.
Ying Yong Sheng Tai Xue Bao. 2011 Jun;22(6):1389-94.
From October 2007 to November 2008, an in situ mesh bag experiment was conducted to study the leaf litter decomposition and nutrient release of forest stands Populus alba var. pyramidalis, Amorpha fruticosa, and P. alba var. pyramidalis + A. fruticosa in a shelter belt in Karamay, Xinjiang. It was observed that the mass loss rate of leaf litter differed with tree species, and was significantly affected by leaf litter composition. The leaf litter of P. alba var. pyramidalis + A. fruticosa was more easily decomposed than that of the other two mono-dominance forest trees. The analysis with improved Olson' s exponential model indicated that P. alba var. pyramidalis leaf litter had the lowest decomposition coefficient (k = 0.167), while P. alba var. pyramidalis + A. fruticosa leaf litter had the highest one (k = 0.275). According to the model, it would cost for about 2.41-4.19 years and 10.79-17.98 years to have 50% and 95% decomposition of the three kind leaf litters, respectively. The residual rates of nitrogen, phosphorus, and potassium in the three kind leaf litters differed with decomposition period. After one year decomposition, potassium was wholly released, while nitrogen and phosphorus were immobilized or enriched via the absorption from surrounding environment. Except that the A. fruticosa leaf litter had a decreased organic carbon decomposition rate in the mid period of decomposition, the leaf litters of P. alba var. pyramidalis and P. alba var. pyramidalis + A. fruticosa all had an increasing organic carbon decomposition rate with the decomposition, which was about 35.5%-44.2% after one year decomposition. The C/N value of the leaf litters had a decreasing trend, and the decrement was smaller in the early and mid periods but larger in the late period of decomposition.
2007年10月至2008年11月，在新疆克拉玛依的一条防护林带开展了原位网袋实验，以研究新疆杨、紫穗槐以及新疆杨 + 紫穗槐林分的凋落物分解及养分释放情况。结果表明，不同树种的凋落物质量损失率存在差异，且受凋落物组成的显著影响。新疆杨 + 紫穗槐的凋落物比其他两种单一优势树种的凋落物更容易分解。采用改进的奥尔森指数模型分析表明，新疆杨凋落物的分解系数最低（k = 0.167），而新疆杨 + 紫穗槐凋落物的分解系数最高（k = 0.275）。根据该模型，三种凋落物分别达到50%和95%分解所需时间约为2.41 - 4.19年和10.79 - 17.98年。三种凋落物中氮、磷、钾的残留率随分解时间而变化。分解一年后，钾全部释放，而氮和磷则通过从周围环境吸收而被固定或富集。除紫穗槐凋落物在分解中期有机碳分解速率下降外，新疆杨和新疆杨 + 紫穗槐凋落物的有机碳分解速率均随分解过程而增加，分解一年后约为35.5% - 44.2%。凋落物的C/N值呈下降趋势，在分解前期和中期下降幅度较小，而在分解后期下降幅度较大。
