神农架海拔梯度上4种典型森林凋落物现存量及其养分循环动态

研究神农架地区典型森林凋落物现存量及其养分动态对认识我国北亚热带森林生态系统养分循环过程及森林碳循环的机理具有重要的参考价值。通过对神农架海拔梯度上4种典型森林常绿阔叶林、常绿落叶阔叶混交林、落叶阔叶林及亚高山针叶林凋落物年凋落量及其养分归还量的研究,发现:森林凋落物量随海拔增加呈现先上升后降低的趋势,由低海拔到高海拔,凋落物年凋落量分别为6807.97、7118.14、6975.2和4250.67 kg/hm²。各森林类型凋落物量年变化呈双峰型,高峰期出现在4-5月份、11月份。凋落物养分归还以N 最高(132.06、162.29、157.12和185.77 kg/hm²),以P最少(4.62、4.39、8.24和4.15 kg/hm²),养分归还总量随海拔高度增加而减少。

Dynamic characteristics of litterfall and nutrient return of four typical forests along the altitudinal gradients in Mt. Shennongjia, China

To explore the litterfall and their seasonal dynamics of the four typical forests along the altitudinal gradient in Mt. Shennongjia, Hubei. We measured litterfall of Evergreen broad-leaved forest (EBF), Mixed evergreen and deciduous broad-leaved forest (MF), Deciduous broad-leaved forest (DBF), and sub-alpine coniferous forest (CF) in Shennongjia. Litterfall collection was conducted monthly from September 2009 to January 2011. The result showed that the total annual litterfall of the four typical forests along the altitudinal gradient in Mt. Shennongjia was increased and then decreased along the altitude. The annual amounts of EBF was 6 807.97 kg/hm², MF 7 118.14 kg/hm², DBF 6 975.2 kg/hm² and CF 4 250.67 kg/hm². The seasonal dynamics of litterfall iccurred two peaks during the periods from April to May and November annually. The returns of N from the littlefall of four forests along the elevation gradients were 132.06, 162.29, 157.12 and 185.77 kg/hm², and that of P was 4.62, 4.39, 8.24 and 4.15 kg/hm².