西藏色季拉山急尖长苞冷杉林线小气候特征

On Characteristics of Microclimate at Smith Fir Timberline in Sergyemla Mountains,Tibet of China

利用自动气象观测站持续对西藏林芝色季拉山东坡急尖长苞冷杉Abies georgei var.Smithii林郁闭上限（海拔4 320m）数据进行观测,分析林线气候特征如下：1林线空气温度年变化呈现单峰型曲线,年均气温为0.56℃,年温差可达17.6℃;林线年降水总量为1 480.2mm,集中于春夏季节,具有明显的干湿季节变化;林线空气湿度较高,高于河谷地带,年变幅仅有25%,空气湿度年变化较小.2太阳总辐射、光合有效辐射和紫外辐射量年变化均呈单峰曲线,辐射量以12月最低,8月最高.3林线盛行南风和东南风,年平均风速为1.77m/s;以冬春季节风速大.4林线土壤含水量有明显的垂直变化,土壤含水量从10cm土层到100cm土层变化范围为5.25%-19.02%;林线地表土壤温度变化剧烈,年温差可达22.41℃,地表以下土壤温度变化较为平缓,土壤温差随着深度逐渐递减.

In this study,the microclmiate characteristics at the alpine timberline（4 320maltitude）of smith fir（Abies georgeivar.smithii）in Linchi of Tibet have been investigated using continuous data collected from micro-meteorological station.The result showed that at the smith fir timberline in the Sergyemla Mountains,air temperature annual variation presented a single peak curve,the mean annual temperature was 0.56 ℃and annual temperature deviancy was 17.6℃.Annual precipitation was 1 480.2mm,most of which occurred spring and summer.Relative humidity is higher than the valley,and only 25%small changes in relative humidity.Solar radiation,photo synthetically active radiation and ultraviolet radiation changes were a single curve,the lowest amount of radiation in December,the highest in August.Prevailing wind direction were southerly and southeasterly winds.Annual average wind speed 1.77m/s,and maximum wind speed concentrated in the winter and spring.The soil water content between 10 cm layer and100 cm layer was 5.25%-19.02%.Soil temperature variation in layer of 5-100 cm is smaller than the surface（the annual deviation is 22.41 ℃）,and the soil annual deviation gradually decreasing with depth.