减雨对南亚热带马尾松人工林凋落物分解的影响

Effects of throughfall reduction on litter decomposition of Pinus massoniana plantation in subtropical China

为探究气候变化背景下降雨格局改变对马尾松人工林凋落物分解及养分释放过程的影响,以南亚热带马尾松(Pinus massoniana)人工林为研究对象,设置穿透雨减少50%和不减雨(对照)处理,开展连续观测野外降水控制实验。采用凋落物分解袋法,研究了减雨处理对南亚热带马尾松人工林凋落叶分解速率及养分释放的影响,以及凋落叶分解速率的影响因素。结果表明:凋落叶分解2年后,减雨处理和对照林凋落叶残留率分别为38.09%和38.06%;凋落叶分解过程中碳元素表现为淋溶-富集-释放,而氮元素表现为富集,减雨50%在一定程度上促进了氮的富集,但未达到显著水平。相关分析表明,凋落叶的残留率与氮浓度和月积温呈显著负相关,与碳/氮呈显著正相关。本研究发现,减雨50%并未改变马尾松凋落叶分解速率和养分释放模式,凋落叶的残留率与氮浓度、碳/氮及月积温密切相关。

To explore the impact of precipitation pattern change on the litter decomposition and nutrient release under global climate change scenario, an experiment including 50% reduction of throughfall and natural rainfall(control) was conducted in Pinus massoniana plantation. Using litter decomposition bag method, we determined the effect of throughfall reduction on the dynamic changes of decomposition rates and nutrient release of leaf litter, as well as the factors influencing the leaf litter decomposition. The results showed that the remaining mass ratio in the throughfall reduction and control were 38.09% and 38.06%, respectively, after two years of leaf litter decomposition. The carbon content of leaf litter showed a "leaching-enrichment-release" pattern during the decomposition, while nitrogen content of leaf litter was enriched to some extent without a significant difference between the throughfall reduction and control. The correlation analysis showed that remaining mass ratio of leaf litter was significantly negatively correlated with leaf litter N content and monthly accumulated temperature, while was significantly positively correlated with leaf litter C:N ratio. This study suggested that throughfall reduction did not change leaf litter decomposition rate and nutrient release pattern in Pinus massoniana. The degradation of leaf litter was closely related to N content, C:N and monthly accumulated temperature.