西藏色季拉山阳坡林线方枝柏种群结构特征研究  

Ecological Characteristics of Sabina saltuaria Population at the Timberline Ectone on the Sunny Slope of the Sejila Mountain

作　　者：郭其强[1] 卢杰[1] 罗大庆[1] 方江平[1] 王贞红[1] 

机构地区：[1]西藏农牧学院高原生态研究所,西藏林芝860000

出　　处：《西北林学院学报》2010年第2期15-18,44,共5页Journal of Northwest Forestry University

基　　金：国家科技支撑项目(2007BAC06B08);西藏林芝高山森林生态系统国家野外科学观测研究项目(2006-2010);林业生态工程生态效益监测与碳汇计量技术专题子课题(2006BAD03A0702/wb03)

摘　　要：通过对海拔4320m以上林线0．8hm。样地方枝柏（Sabina saltuaria）种群的每木调查，分析了阳坡林线特征、种群结构、数量动态及时间序列预测。结果表明，西藏色季拉山海拔4320m为森林郁闭上限，阳坡林线上限为4520m，属渐变型林线；方枝柏种群径级结构中Ⅰ～Ⅳ龄级个体所占比重较大，此后种群数量随径级增大而急剧减少；种群存活曲线介于DeeveyⅠ和DeeveyⅡ之间，基本趋于稳定。死亡率（qx）和消失率（kr）变化基本趋势一致，都在Ⅲ龄级出现低谷，以后死亡率和消失率曲线均随龄级增加而上升；时间序列分析表明，未来种群发展老龄个体逐渐增多。说明方枝柏种群在Ⅳ龄级前能够适应高山林线区域特殊的生境条件，生长较好并发育到青壮年期，此后由于竞争加剧，导致种群发生自疏。这也是种群自身生物学特性和环境条件等因素共同作用的结果，也是高山生态系统恶劣生境中种群的一种适应对策。Sabina saltuaria is an endemic timberline tree in the Qinghai-Tibetan Plateau, China. It is mainly distributed in the elevations between 4 320 m and 4 520 m on the sunny slope of the Sejila Mountain. One 0.8 hm2 sample plot was established at the timberline 〉4 320 m on the sunny slope of the Mountain. Parameters, such as tree height,DBH,or diameter at base for seedlings and saplings, and location of each individual were recorded. The timberline features, population structure,dynamic and the time sequence prediction were investigated. The results showed that： （1）the upper elevation limit of the closed forests was found to be 4 320 m; the timberline elevations was 4 520 m on the sunny side with a gradualtype; （2） for the diameter class structure of the populations, most individuals were from Ⅰ to Ⅳ, the number decreased sharply with the increase of diameter class, the survival curves were between Deevey type Ⅰ and Ⅱ , with an approximately stalbe trend; the variation trends of mortality rate （qz） and hazard rate （kx） were simi- lar; （3）the analysis by time sequence model demonstrated that the individuals of the older age class would be increasing, indicating that S. saltuaria grew well before reaching the age class Ⅳ, and could adapt the timberline habitat conditions; but after Ⅳ ,population self-thinning appeared because of the fiercer competition. It resulted from the biological characteristic of S. saltuaria, environment,as well as an adaptation strategy in ecological restoration of the high-altitude ecosystem.

关 键 词：方枝柏 年龄结构 生命表 存活曲线 时间序列 

分 类 号：S718.54[农业科学—林学]