海南尖峰岭热带山地雨林凋落物产量及其动态

Dynamics of litterfall production in the tropical mountain rainforest of Jianfengling,Hainan Island,China

热带山地雨林是海南尖峰岭地区面积最大的植被类型,是陆地生态系统重要的组成部分,研究海南尖峰岭热带山地雨林凋落物产量的长期动态变化规律及其影响因素,有助于了解未来气候环境变化背景下热带森林的响应规律。本研究采用尼龙网收集框法于2013-2017年对尖峰岭60hm2大样地内132个样方的凋落物产量进行为期5年的连续定位观测,测定枝、叶、杂物(含花、果和枝叶碎片)的组分产量,探讨其与气候因子的相关关系。研究结果显示:尖峰岭热带山地雨林年凋落物总产量为617.5~1084.7g/m^2,年均768.6g/m^2,各组分凋落物平均产量由大到小为:叶>枝>杂物,其值分别为507.9、163.4、97.3g/m^2,凋落叶产量占66.1%,为优势组分;凋落物总产量的季节变化为不规则型,出现3次峰值,各组分凋落物产量季节变化呈双峰型,峰值月存在差异;春季、秋季和冬季以叶凋落为主,夏季以枝凋落为主;凋落物总产量及各组分产量受不同气象因子的影响,凋落枝产量与各气象因子均无显著相关,凋落叶产量与月极小气温和平均气温显著相关,凋落杂物产量与日最高气温显著相关,凋落物总产量与平均气温显著相关。研究结果表明海南热带森林凋落物产量一年间呈现3次峰值,其动态变化是受多种气象因素特别是受极端气候因子的影响,这对于了解未来气候环境变化背景下热带森林的响应规律具有重要参考价值。

Tropical mountain rainforest is the dominant vegetation type in Jianfengling, Hainan Island, and is an important part of the terrestrial forest ecosystem. Analysis of the long-term dynamics and influencing factors of litterfall production in Jianfengling could improve our understanding of how tropical forests respond to future climate and environmental changes. Based on a 60 hm 2 plot in the tropical mountain rainforest of Jianfengling, we continuously monitored litterfall production using 132 nylon mesh sampling traps from 2013 to 2017. All litterfall products were classified into leaves, branches, and debris to determine the seasonal dynamics and correlation between production and meteorologic al factors. Results showed that annual litter production ranged from 617. 5 to 1084. 7 g/m^ 2, with an average production of 768. 6 g/m^ 2 per year. Average production of the litterfall products ranked leaves > branches > debris, with 507. 9 g/m 2, 163. 4 g/m^ 2, and 97. 3 g/m^ 2 per year, respectively. Leaf litterfall was the dominant component, contributing 66. 1% to total litterfall. The seasonal variation pattern of total production was irregular and showed three peaks, whereas litterfall production for each component showed two peaks, although the peak months differed. Total and component litterfall production were influenced by different meteorological factors. Branch litterfall had no significant relationship with any meteorological factor, whereas leaf litterfall was correlated with monthly minimum temperature and average temperature, debris litterfall was correlated with daily maximum temperature, and total litterfall was correlated with average temperature. Therefore, we identified three seasonal peaks in total litter production and determined that the dynamic changes in forest litterfall were influenced by various meteorological factors, especially extreme climate factors.