青藏高原自然植被总生物量的估算与净初级生产量的潜在分布*

以800多块样地资料及森林和草地资源调查数据为基础,按县级为单位估算了青海和西藏两省区的自然植被总生物量,分别为2.586×10⁸t和1.282×10⁹t.建立的QZNPP模型显示,随着温度的增加,生物生产量呈S型曲面递增,且其递增速率随降水量增加而加快;当年均温度0℃～10℃和年降水量400mm～1000mm时,生物生产量增长最快;当年均温度>11℃和年降水量>1 100mm时,生物生产量趋向于20t/hm²·a;在年均温度<0℃时,相对降水量的增加,生物生产量呈缓慢的递减趋势,说明这时温度是影响生物生产量的主导因子。两省区115个县的生物量现实分布图显示,生物量最高值出现在西藏墨脱,其次是西藏的察隅、波密、林芝和米林,青藏高原中部及西北部的广阔地区最低。青藏高原自然植被净初级生产量最小值为0,最大值为20t/hm²·a,全区平均为6.03t/hm²·a,低于世界陆地植被的平均水平

ESTIMATION OF TOTAL BIOMASS AND POTENTIAL DISTRIBUTION OF NET PRIMARY PRODUCTIVITY IN THE TIBETAN PLATEAU

Based on more than 800 measured plots and the inventory data of natural resource survey,the total biomass of natural vegetation was estimated for various counties of Qinghai and Tibet provinces,which was 2.586×10⁸t for Qinghai and 1.282×10⁹t for Tibet.The QZNPP model established here shows that,as temperature rises by degrees,net primary productivity (NPP) increases in the way of "S" curve;the rate of increasing is quickened by more precipitation.The rapidest rate appears when the annual mean air temperature is 0℃～10℃ and the annual precipitation is 400 mm-1 000 mm.When the temperature is over 11℃ and the precipitation is more than 1 100 mm,NPP approaches a maximum of 20 t/ha·a;and in the condition of less than 0℃,with the increasing of precipitation,NPP declines slowly,indicating that temperature is a major limiting factor.A biomass map for the 115 counties in Qinghai and Tibet provinces shows that,the maximum biomass occurs in Motuo County of Tibet,up to 196 539 t/ha;the second is in Chayu,Bomi,Linzhi and Milin counties of Tibet,whichis 115 t/ha～140 t/ha;the value is only 1 t/ha～5 t/ha in the extensive regions in north west Tibetan Plateau.A map of potential NPP for the natural vegetation of the Tibetan Plateau indicates that NPP varies from 0 to 20 t/ha·a;the area weighted average of NPP is 6.03 t/ha·a,less than the value of the global terrestrial vegetation (7 82 t/ha·a).