宁南山区半干旱草原典型植物立枯物的碳矿化特征

为探究宁南山区典型植物立枯物添加到土壤后的碳矿化特征，采用室内培养法（28℃下培养61 d），对5种典型植物立枯物添加到土壤后的碳矿化特征进行了研究。结果表明：添加立枯物后的土壤有机碳矿化速率呈现2个阶段，前期（0~11 d）速率较大且迅速降低，后期速率较小且保持平稳，到培养结束时速率仅为初始速率的5.37%~13.98%。并且受矿化速率的影响，有机碳累积矿化量前期增加很快，之后逐渐减慢。前期（0~11 d）各处理有机碳累积矿化量占到总矿化量的30.43%~50.51%。用一级动力学方程对立枯物自身释放的CO₂-C量进行模拟，得到的矿化速率常数k以及立枯物的分解率均与立枯物木质素含量成显著负相关，说明立枯物的木质素含量及其碳矿化速率与分解率有密切关系，木质素含量越高，越不利于立枯物的分解。

Carbon Mineralization Characteristics of the Typical Plant Litters of Semiarid Grassland in the Mountain Area of Southern Ningxia

The litter mineralization characteristics of five typical plant species (Agropyron cristatum, Stipa bungeana, Artemisia gmelinii, Artemisia giraldii, Thymus mongolicus) in the mountain area of southern Ningxia were investigated using a laboratory incubation method. Results showed that organic carbon mineralization of soil with litters had two stages. Mineralization rate was very high and declined quickly in prior period (0~11 d), then became steady in later period. The final mineralization rates were 5.37~13.98 percent of initial rates. Affected by mineralization rate, the cumulative CO₂-C increased fast then turned slow. The cumulative CO₂-C in prior period even accounted for 30.43~50.51 percent of that in the whole incubation period. The curves of the cumulative CO₂-C released by litters were simulated according to the first order kinetic equation. The mineralization rate constant (k) and decomposition rate had a significant negative correlation with the lignin contents of litters. These results indicated that the lignin content of litter was related to both mineralization rate and decomposition rate, and the higher lignin content litter had, the harder the litter was decomposed.