摘要
为了探究祁连山青海云杉的径向生长变化规律,以祁连山排露沟小流域的青海云杉林为研究对象,通过对森林分布上、下限的样地调查和生长尺的连续观测,分析树木直径结构对青海云杉年内径向生长的影响。结果表明:(1)海拔2 500 m的青海云杉林以4~8 cm径阶的树木居多,林分直径结构分布趋势呈反"J"形,基本符合天然异龄林分布曲线;海拔3 300 m的林分中,大径级树木数量较海拔2 500 m明显增多,林分直径结构分布呈现为近似余弦曲线分布,属于异龄林分布曲线的中间型。(2)海拔2 500 m和3 300 m青海云杉的生长季均于5月开始至9月底。可将其生长期划分为启动生长期(5月)、快速生长期(6—8月)和缓慢生长期(9月),平均径向生长速率分别为-0.66μm·d^(-1)·株^(-1)、7.59μm·d^(-1)·株^(-1)、5.16μm·d^(-1)·株^(-1)。(3)树木径向生长速率随着树木直径的增大而增大。大树平均生长速率为6.91μm·d^(-1)·株^(-1),是中树的1.65倍,是小树的7.3倍。(4)不同径级的青海云杉年径向累积生长量为:中树>小树>大树。中树的年径向累积生长量为9 137.5μm,是大树的2.85倍,是小树的3.38倍。
Picea crassifolia forest plays an important role in water conservation,the stand structure and the growth conditions of the forest are strongly affected by the ecological process and hydrological regime in mountainous area.In order to investigate the variation of radial growth of P. crassifolia,the P. crassifolia forest in altitude range of2 500-3 300 m a. s. l. in the Pailougou drainage basin on the northern slope of the middle Qilian Mountains was studied by surveying the sample plots,regularly observing the tree growth and analyzing the diameter structure and its effect on radial growth of P. crassifolia forest in growth season. The results were as follows： Proportion of the trees with small diameter（ 4-8 cm） was high in P. crassifolia forest,the diameter structure of trees in the forest was in a reverse J-type distribution at altitude of 2 500 m. The trees with big diameter increased gradually,and the distribution of stand diameter structure was in an approximate cosine curve,which was an intermediate type of uneven-aged forest distribution curve at altitude of 3 300 m. The growth period of P. crassifolia at altitudes of 2 500 m and 3 300 m was from May to late September,and it could be divided into 3 growth phases,i. e. the initial growth phase（ May）,rapid growth phase（ from June to August） and slow growth phase（ September）,the average radial growth rates in these growth phases were-0. 66,7. 59 and 5. 1 μm·d^-1·tree^-1respectively. In the study area,the radial growth rate of the trees increased with the increase of diameter. The average growth rate of the trees with big diameters was 6. 91 μm·d^-1·tree^-1,it was 1. 65 times of that with middle diameter and 7. 3 times of that with small diameter. The cumulative radial growth of the trees with middle diameter was higher than that with big and small diameter due to the influence of stand density,and it was 9 137. 5 μm equivalent to 2. 85 times of that with big diameter and 3. 38 times that with small diameter.
出处
《干旱区研究》
CSCD
北大核心
2017年第5期1117-1123,共7页
Arid Zone Research
基金
国家自然科学基金项目(41461004
91225302
91425301)
甘肃省基础研究创新群体项目(145RJIG337)
甘肃省自然科学基金项目(1308RJZA256)资助
