亚高山暗针叶林凋落物的分解过程

凋落物是森林生态系统的重要组成部分,其分解过程是森林生态系统养分循环的重要环节。准确测定凋落物的分解动态,对研究森林生态系统的格局和过程非常重要。本文的工作在贡嘎山高山生态系统观测试验站开展,对海拔3 000 m的峨眉冷杉(Abies fabri)林进行定位观测,并对峨眉冷杉林凋落物分解过程进行了长期测定。研究结果表明:(1)凋落物的分解速率是阔叶>针叶>枯枝,峨眉冷杉林的阔叶、针叶和枯枝等凋落物分解一半所需要的时间分别为6.8年、10.5年和14.5年,分解95%所需时间分别为29.3年、45.6年和63.1年;(2)无论阔叶还是针叶、枯枝,其有机碳含量均随着时间的推移而下降,而有机碳分解率均随着时间而增高;利用指数衰减模型,获得凋落物有机碳的分解系数是阔叶>针叶>枯枝;(3)在每年凋落物输入峨眉冷杉林林地时,其中的阔叶、针叶和枯枝已经开始分解,当年可释放的有机碳分别为52.18 kg·hm^-2、4.32 kg·hm^-2和0.67 kg·hm^-2,各类凋落物每年有机碳释放总量为61.13 kg·hm^-2,占凋落时有机碳量的6.58%。

Decomposition Process of Litterfall in Subalpine Dark Coniferous Forest

Litterfall is an important part of forest ecosystem and its decomposition process is the key processes of nutrient cycling in the forest ecosystem.Accurate determination of litter decomposition dynamics is very important for studying the pattern and process of forest ecosystems.Observations and determination were made of litter decomposition process of the Abies fabri forest in the Alpine Ecosystem Observation and Experiment Station at an altitude of 3 000 m over a long period of time.The results showed that(1) the decomposition rate of litterfall was listed in descending order:broadleaves > needles > twigs,and the time required to decompose the half of broadleaves,needles and twigs was 6.8 years,10.5 years and 14.5 years respectively;and the time to decompose 95% of them was 29.3 years,45.6 years and 63.1 years,respectively.(2) Regardless of broadleaves,needles or twigs,the organic carbon content of them decreased with time,while the decomposition rate of organic carbon increased with time;By the exponential decay model,the decomposition coefficient of litterfall organic carbon was calculated and listed as:broadleaves > needles > twigs.(3) The organic carbon released by the annual decomposition of broadleaves,needles and twigs in Abies fabri forest was 52.18 kg·hm^-2,4.32 kg·hm^-2 and 0.67 kg·hm^-2,respectively.The total amount of organic carbon released by various litterfall was 61.13 kg·hm^-2 per year,accounting for 6.58% of the total organic carbon of litterfall.