网袋埋藏和自然环境下测定森林凋落物早期分解过程的比较

Comparison on Early Decomposition Process of Forest Litter from Litter Bag and Natural Environment

为比较网袋埋藏和自然环境中凋落物分解速率的差异,探讨网袋在凋落物早期分解过程中对分解速率的影响,选取位于北京市东灵山的暖温带落叶阔叶林为固定样地,于2007年11月至2008年11月定期收集网袋和自然分解早期凋落物,并收集分解后期近10年的样品作为对比,测定其红度(a^*)、黄度(b^*)和亮度(L^*)。结果表明,网袋中的凋落物和自然环境中的凋落物的a^*,b^*,L^*均随分解时间的推移而逐渐降低,颜色变化主要发生在分解的第1年,分解后期颜色逐渐趋于稳定;分解早期,对a^*,b^*,L^*而言,三者间呈极显著的正相关,a^*,b^*,L^*与分解时间之间均呈显著负相关;网袋中凋落物的颜色值波动较大,分布离散,规律性较差;分解开始,网袋中的凋落物与自然环境中的凋落物的颜色接近,随着时间的推移,差别逐渐增大,凋落物的颜色变化是色素等有机质分解的外在表现,时间较长时,网袋微环境会抑制凋落物分解,使其分解速率低于自然样品。因此,利用网袋法研究凋落物分解过程和分解速率,应适当考虑网袋的存在对分解的影响以使结果更加精准。

Permanent sample plots were established in 2007 in warm temperate deciduous broad-leaved forest in Donglingshan Mountain,Beijing for studying early decomposition of litter.From November 2007 to November 2008,samples from litter bag and natural environment were collected regularly and their color values(a^*,b^*,L^*)were measured.Samples from 2009 to 2018 were collected from the same sample plots for comparison.The results indicated a^*,b^*,L^*gradually decreased with the increase of time.Color change of litter mainly occurred in the first year of decomposition,and then gradually stable in the later stage.At the early stage of decomposition,there were significantly positive correlations among three indexes,and significantly one among decomposition years.At early stage,color was similar of samples from litterbag and natural environment,but later there were difference between them at later stage.