“一江两河”中部流域植被净初级生产力估算

基于中分辨率成像光谱仪（MODIS）的遥感数据以及地面实际观测资料，采用数学模型方法，对西藏“一江两河”中部流域地区2000和2006年的植被净初级生产力（NPP）进行了估算.结果表明：研究区NPP由河谷向山脊逐渐递减，这与该区的水热梯度基本一致；该区单位面积年NPP平均为86.8 g C·m^-2·a^-1，2006年比2000年高2.15 g C·m^-2·a^-1，不同植被类型的单位面积年NPP以农田(243.1 g C·m^-2·a^-1)最大，荒漠(35.6 g C·m^-2·a^-1)最小；研究区两年平均总NPP为512.8×10¹⁰ g C·a^-1，2006年比2000年高12.7×10¹⁰ g C·a^-1，不同植被类型的总NPP以草甸(194.4×10¹⁰ g C·a^-1)最高，荒漠(30.3×10¹⁰ g C·a^-1)最低.研究期间，人类活动强烈区域（道路缓冲区0～4 km）的植被NPP呈下降趋势，而人类活动较难到达区域的植被NPP呈增加趋势.

Estimation of net primary productivity in middle reaches of Yarlung Zangbo River and its two tributaries.

Based on the MODIS data and field measurement, the net primary production (NPP) in 2000 and 2006 in the middle reaches of Yarlung Zangbo River and its two tributaries in Tibet were estimated by using a mathematic model. The results showed that in study area, the NPP decreased gradually from valley to ridge, which was accorded with the gradients of precipitation and temperature. The annul NPP per unit area was averagely 86.8 g C m(-2) a(-1), and was 2.15 g C m(-2) a(-1) higher in 2006 than in 2000. Farmland ecosystem had the highest annual NPP per unit area (243.1 g C m(-2) a(-1)), while desert ecosystem had the lowest one (36.5 g C m(-2) a(-1)). The average total NPP in the two years was 512.8 x 10(10) g C a(-1), with the value in 2006 being 12.7 x 10(10) g C a(-1) higher than that in 2000. Meadow ecosystem had the highest annual total NPP (194.4 x 10(10) g C a(-1)), while desert ecosystem had the lowest one (30.3 x 10(10) g C a(-1)). In 2000-2006, the NPP value in the areas with strong human disturbance (0-4 km away from road) had a decreasing trend, while that in the areas difficult for human to reach was in adverse.