增温对亚热带常绿阔叶林凋落物溶解性有机质的影响

Effect of Warming on Dissolved Organic Matter in Litter of Subtropical Evergreen Broad-leaved Forest

为了解增温对凋落物分解的影响,依托亚热带常绿阔叶林野外增温试验平台,收集林内凋落物分别布设于对照和增温(+4℃)小区中,对增温下凋落物分解过程中可溶性有机质数量和光谱特征的变化进行研究。结果表明,凋落物质量残留率随分解时间的增加显著下降,在0~60 d内快速下降了20.08%~23.32%,在60~210 d内缓慢下降了6.35%~10.98%。凋落物源可溶性有机碳含量随分解时间增加呈现先快后慢的下降趋势,整体降低了94.15%;可溶性有机氮含量则波动式降低了81.82%;可溶性有机质的光谱特征(SUVA254、SUVA260、SUVA280和SUVA370)呈增加-下降-增加的趋势。增温未显著影响凋落物质量残留率和可溶性有机质的光谱特征,但可溶性有机碳和有机氮的含量降低了16.72%和25.10%。凋落物分解降低了凋落物质量残留率和可溶性有机碳、有机氮含量,改变了可溶性有机质光谱特征;增温虽然降低了凋落物可溶性有机碳、有机氮含量,但未显著改变凋落物质量残留率和可溶性有机质光谱特征。

In order to understand the effect of warming on litter decomposition,the litter collected in subtropical evergreen broad-leaved forest was distributed in control and warming(+4℃)plots,respectively.The changes in the quantity and spectral characteristics of dissolved organic matter during litter decomposition under warming were studied.The results showed that the mass residual rate of litter decreased significantly with decomposition process,rapidly decreased by 20.08%to 23.32%in 0–60 days,and slowly decreased by 6.35%to 10.98%in 60–210 days.Along decomposition process,the dissolved organic carbon content of litter source showed a decreasing trend of first fast and then slow,and the overall decrease was 94.15%.The content of dissolved organic nitrogen fluctuating decreased by 81.82%overall.The spectral characteristics of dissolved organic matter(SUVA254,SUVA260,SUVA280 and SUVA370)showed an increase-decrease-increase tendency.The warming did not significantly affect the mass residual rate of litter and the spectral characteristics of dissolved organic matter,but the contents of dissolved organic carbon and organic nitrogen decreased by 16.72%and 25.10%.Therefore,the decomposition of litters decreased the mass residual rate of litters and the contents of dissolved organic carbon and organic nitrogen,and changed the spectral characteristics of dissolved organic matter.Although warming decreased the contents of dissolved organic carbon and organic nitrogen in litters,it did not significantly change the mass residual rate and spectral characteristics of dissolved organic matter in litters.