北京地区40a生油松人工林密度效应的研究

Management Density Effects of Pinus Tabulaeformis Plantation in Beijing

以20块6种不同密度梯度的北京地区低山阴坡厚土40a左右油松人工林为研究对象,分析其林分生长、树冠生长、林下植物多样性以及林下生物量对林分密度的响应关系,研究结果表明：胸径、树高、冠幅随林分密度的增大而减小,当林分密度增大到1 500株/hm^2时,减小的趋势趋于稳定;枝长平均生长量、连年生长量均随年龄的增大有先增加后下降的趋势,林分密度〉1 500株/hm2时,枝生长量下降趋势明显;枝材积生长量在各年龄阶段的变化也随林分密度的增大表现出抑制响应,与枝长生长量的变化规律类似;林下灌木、草本物种均匀度指数Jsw,Simpson多样性指数和Shannon-Wiener多样性指数均随林分密度的增大而减小;随林分密度的减小,草本层生物量逐渐增加,灌木层生物量先增加后略减,林分密度为1 000~1 200株/hm^2时灌木生物量最大,为3 802.94kg/hm^2。对于北京低山阴坡厚土40a左右的油松人工林来说,经营密度宜为1 000~1 500株/hm2。

This paper studied the changes in stand crown growth of Pinus tabulaeformis plantation （40 growth, understory plant diversity, forest biomass and years old or so） under the different conditions of stand density at low hill shade slope. Results showed that：DBH, tree height, crown width decreased with stand density increase ,when stand density increases to 1500 individuals per hectare ,the reduced tendency was to stabilize. The average amount of branch length growth, year after year volume growth increased with age increase and then decreased afterwards. With stand density 〉 1500 individuals per hectare ,the average amount of branch length growth decreased significantly. Branch volume increment also increases with stand density that shows inhibition of response, and the amount of branch length variation of a similar growth. As stand density increases, the understory shrubs, herbaceous species evenness index Jsw, Simpson diversity index and Shannon-Wiener diversity index decreased. With stand density decreases, the herb layer biomass increased gradually, shrub layer biomass increased and slightly reduced. The biomass of shrubs was maximum when stand density was 1000 - 1200 individuals per hectare. For Beijing low hill shade slope Pinus tabulaeformis plantation （40 years old or so）, the management density is between 1000 - 1500 individuals per hectare.