植被退化对尕海湿地枯落物分解的影响

Effects of Vegetation Degradation on Litter Decomposition in Gahai Wetland

[目的]分析植被退化对青藏高原东部尕海湿地枯落物分解的影响,为湿地生源要素生物地球化学循环过程研究提供基础依据。[方法]采用分解袋法,研究尕海泥炭沼泽和沼泽化草甸不同植被退化梯度湿地枯落物分解特征及其影响因素。[结果]各植被退化阶段湿地枯落物分解过程存在显著差异,植被退化总体抑制了枯落物分解,但不同湿地类型枯落物分解对植被退化响应有所不同;在生长季内(5—9月),沼泽泥炭植被未退化枯落物分解速率显著高于退化(p<0.05);沼泽化草甸平均分解速率排序为:未退化(0.028 9g/d)>中度退化(0.028 7g/d)>轻度退化(0.028 0g/d);各植被退化阶段湿地的枯落物分解过程具有明显的年际变化特征,总体表现为2014年分解较快,2015,2016年相对较慢;温度和降雨对各退化阶段枯落物分解速率具有促进作用,但作用不显著。[结论]尕海湿地植被退化过程中枯落物分解动态受到枯落物自身性质、气候条件、土壤营养状况等自然环境条件的共同影响,相比而言,受枯落物性质的影响更大。

[Objective] To analyze the effects of vegetation degradation on litter decomposition in Gahai wetland in the Eastern Qinghai-Tibet Plateau, we aim to provide the basis for research on biogeochemical cycles of biogenic elements in wetland.[Methods] Using the litter bag technique, we examined the decomposition rates and their influencing factors in typical peatlands and swamp meadows in the Gahai wetland.[Results] There were significant differences in litter decompositions among different vegetation degradation stages. Vegetation degradation inhibited litter decomposition in general, but the responses varied with different wetland types. In the growing season （from May to September）, the litter decomposition rates of undegraded healthy vegetation were significantly higher than that of degraded vegetation （P〈0.05）. The order of average decomposition rates in swamp meadows was, undegraded （0.028 9 g/d） 〉 medium degraded （0.028 7 g/d） 〉 slightly degraded （0.028 0 g/d）. There were clear inter-annual variations of litter decompositions for each vegetation degradation stages. For all three years, in the growing season, the litter decomposition rates were faster in 2014 while relatively slower in 2015 and 2016. Temperature and precipitation conditions enhanced litter decomposition, but the effect was not significant.[Conclusion] The decomposition rates were simultaneously influenced by the quality of the litter, meteorological characteristics and soil environmental factors. In comparison, the effect of the quality of the litter was greater.