神农架巴山冷杉林凋落物量养分归还及分解特征

【目的】掌握森林凋落物产量及组成的动态变化、凋落物养分归还量及凋落物分解特征,了解凋落物在森林生态系统养分循环中的作用。【方法】选择神农架巴山冷杉天然林和人工林,在样地内布置凋落物收集框和凋落物分解袋,通过1 a的连续观测,比较天然林和人工林凋落物产量及分解速率的差异。【结果】巴山冷杉天然林和人工林年凋落物总量分别为6 217.44和4 833.46 kg/hm²,天然林比人工林年凋落物总量高28.63%。凋落物中以落叶为主,天然林和人工林落叶产量分别占凋落物总量的55.24%和54.76%; 其次是落枝,分别占总量的22.18%和19.66%; 树皮及花果等其他组分含量相对较少,分别占总量的22.58%和25.58%。巴山冷杉林凋落模式为双峰型,分别在10月和次年6月具有明显高峰期,而在次年2月凋落量最小。天然林和人工林凋落物养分年归还量分别为77.84和54.47 kg/hm²,天然林比人工林凋落物年养分归还量高42.91%,5种大量元素年归还量大小顺序均为N＞K＞Ca＞P＞Mg。凋落物在初始阶段分解较快,天然林和人工林凋落物在最初2个月失重率分别达18.70%和11.35%。天然林和人工林凋落物分解常数分别为0.303和0.241,凋落物半衰期分别为1.70 a和2.57 a,而凋落物周转期分别为9.30 a和12.12 a。【结论】神农架巴山冷杉林凋落物产量较高,分解速率较慢,天然林凋落物对土壤的改良效果更好。

Characteristics of litter production dynamic and decomposition process of Abies fargesii forest in Shennongjia,Hubei Province

【Objective】 In order to reveal functions of litter in nutrient cycling of forest ecosystem, the dynamics of litter production and components, nutrient return and characteristics of decomposition process were studied in this paper. 【Method】We choose the natural and plantation forest of Abies fargesii in Shennongjia,and arranged litter collection boxes and decomposition bags in the sample area, to compare the litter production and decomposition rate differences between the natural forest and plantations through one year of continuous observation.【Result】①The total litter production of natural forest and plantation were 6 217.44 kg/hm² and 4 833.46 kg/hm², respectively, which of the natural forest was 28.63% higher than that of the plantation. ②The main litter fractions were leaves which accounted for 55.24%(natural forest)and 54.76%(plantation)to total litters, then the twigs(22.18%, 19.66%), and the barks, fruits and others were less relatively(22.58%, 25.58%). ③The annual dynamics mode of litter production was double peak curve, and the peak occurred in October and next June, and the nadir occurred in next February. ④The annual nutrient returns of natural forest and plantation forest were 77.84 kg/hm² and 54.47 kg/hm² respectively, which of the natural forest was 42.91% higher than that of the plantation, and the order of macro-element return was N＞K＞Ca＞P＞Mg. ⑤The litters were decomposed more fast in the initial phase, as the litter weight loss rate of natural forest and plantation express 18.70% and 11.35%,respectively. The litter decomposition constants of natural forest and plantation forest were 0.303 and 0.241, the half declining were 1.70 and 2.57 years, and the total declining were 9.30 and 12.12 years. 【Conclusion】 The litter production of A. fargesii forest is abundant, the litter decomposition rate of it is slow, and the effect of litters on soil improvement in natural forest is better than that in the plantation forest.