论文部分内容阅读
一、西藏东南部拥有极丰富而特异的地貌类型、生态类型、生物种群和森林植被类型。藏东南林区有大面积古老,健康而完好的天然森林生态系统。其中亚高山暗针叶林是分布广、面积大、稳定性强、生物生产量高的森林群系。 二,西藏亚高山暗针叶林是寒温带暗针叶林分布最南、最高的林区之一。由于地带三向性的分异,亚高山暗针叶林有明显的水平分区和垂直分带。在各区,带中,森林群系,建群种,林型及其生长状况都有明显的差异。 三,西藏亚高山暗针叶林的水平分布可分为三亚区:(1)三江流域峡谷、山原块状暗针叶林亚区;(2)喜马拉雅山南麓高山峡谷湿润暗针叶林亚区;(3)雅鲁藏布江中下游沟谷暗针叶林亚区。 在分布区的海拔2700—4300米的垂直带内,分布有云杉林群系、冷杉林群系和圆柏林群系。各群系的分布带内,随水热状况的变化组成有规律的林型垂直分布带谱。 四、西藏亚高山暗针叶林的生长特点为;立木高大,生长持续期长,林分蓄积量高。在喜马拉雅山南麓湿润区,云杉林分的蓄积最高达每公顷3500余立方米,平均胸径111厘米,平均高67米。立木最大胸径162厘米,最大树高72米。 五、不同海拔高度与坡向的暗针叶林林分生长差异显著。在喜马拉雅山南麓湿润区,云杉的最适分布带在海拔2700—2800米,冷杉的最适分布带在海拔3600?
First, there are extremely rich and specific landform types, ecological types, biological populations and types of forest vegetation in southeastern Tibet. Southeast southeast of Tibet has a large area of ancient, healthy and intact natural forest ecosystems. The sub-alpine dark coniferous forest is widely distributed, large area, strong stability, high biological production of forest group. Second, the Tibetan sub-alpine dark coniferous forest is one of the southernmost and highest forest regions in the frigid temperate dark coniferous forest. Due to the differentiation of the three-way zone, sub-alpine dark coniferous forest has obvious horizontal division and vertical zonation. In each district, belt, forest group, build group species, forest type and their growth conditions have obvious differences. Thirdly, the horizontal distribution of dark coniferous forest in sub-alpine mountains in Tibet can be divided into three sub-regions: (1) the valley of Sanjiang River basin and the dark coniferous forest in the mountainous plain; (2) the moist dark coniferous forests in the south of the Himalayas Area; (3) the middle and lower reaches of Brahmaputra dark coniferous forest area. In the distribution area of 2700-4300 meters above sea level in the vertical distribution of spruce forest group, Abies fir forest group and circle berlin group. The distribution of each group within the band, with the changes in hydrothermal conditions form a regular forest vertical distribution band spectrum. Fourth, the growth characteristics of dark-coniferous dark-coniferous forests in Tibet are: tall stands, long-term growth and high stand volume. In the humid zone south of the Himalayas, spruce stands accumulate up to 3500 cubic meters per hectare with an average breast diameter of 111 cm and an average height of 67 meters. Rising wood maximum diameter of 162 cm, the maximum height of 72 meters. The differences of growth of dark coniferous forest with different altitudes and slope directions were significant. In the humid area south of the Himalayas, spruce the most suitable distribution belt at 2700-2800 meters above sea level, fir the most suitable distribution belt at an altitude of 3600?