植物质量、模拟增温及生境对凋落物分解的相对贡献

采用凋落物袋法对比研究了茭草和杉叶藻两种初始质量差异显著的湿地植物凋落物,在模拟增温(1.5～2.0 ℃)及不同生境(大气、大气-水界面与水-土界面)下的质量残留率和不同化学组分的含量变化.结果表明: 在一年的分解周期内,凋落物残留率表现出季节性变化特征,并与环境因子之间存在显著的交互作用.各因子对凋落物分解的贡献大小不同,植物质量解释了28.8%的变异,模拟增温解释了6.3%的变异,而生境解释了34.9%的变异.随着分解时间的延长,凋落物中不同组分(难、易分解)的含量发生明显变化.杉叶藻中氮含量在分解后期显著降低了53.1%,而木质素含量显著增加了45.4%.生境是影响凋落物分解最重要的环境因子,其次是植物质量,而模拟增温对凋落物分解的影响程度较小.

The relative contributions of plant quality,simulated rising temperature,and habitat to litter decomposition.

With litter bag methods, we examined mass loss rates and different chemical fractions of litters from two wetland plant species, Zizania caduciflora and Hippuris vulgaris. Those two species examined here varied significantly in their initial litter chemical traits. Experiment was performed under simulated rising temperature (1.5-2.0 ℃), and under three different habitats (air, air-water interface and water-soil interface). The results showed that, during one-year decomposition period, the mass resi-dual rates exhibited distinct seasonal dynamics, and there were strong interactive effects between seasonal dynamics and environmental factors. Different factors contributed differently for the variation of litter decomposition, 28.8% of which being explained by litter quality, 6.3% of which being explained by rising temperature, and 34.9% being explained by habitat. Along with the decomposition, the contents of different chemical fractions (easy or hard to decompose) varied greatly. Among them, nitrogen contents in H. vulgaris decreased by 53.1%, while the lignin contents increased by 45.4%. Overall, habitat was the most important factor driving litter decomposition, the second was litter quality, and rising temperature had minor effect.