四川甘孜州2005年-2015年草地长势变化及其影响因素分析

Quantitative assessment of grassland growth and its affecting factors in Ganzi Tibetan autonomous prefecture

甘孜州是四川省重要牧场之一,草地变化影响着当地的生态环境和经济发展。这里以植被净初级生产力(net primary productivity,NPP)为指标评价甘孜州2005年-2015年草地的长势变化,采用综合自然植被净第一性生产力模型和残差分析法定量评估气候和人类活动因素对草地变化的相对贡献,在此基础上分析气候因子和高程与NPP的年际变化及空间分布规律上的相关性。结果表明:(1)研究区2005年-2015年NPP平均为286.6g C/m2,NPP变化具有波动性,草地整体上呈现缓慢退化的趋势;(2)气候、人类活动以及两者综合作用对草地变化的相对贡献率分别为26.5%、61.1%和12.4%,人类活动是草地退化的主要驱动力,气候和人类活动是草地恢复的主导因素;(3)年均温度、日照时数与NPP变化呈正相关,高程、降雨与NPP变化呈负相关,其中年降雨量对NPP年际变化的相对影响最大。

Ganzi prefecture is one of the important pasture,local ecological environment and economic development were affected by it＇s grassland changes.This paper evaluates the grassland growth in Ganzi prefecture in the 2005-2015 with the net primary productivity（net primary productivity,NPP）of vegetation,the relative contribution of climate and human activities to grassland change was quantitatively assessed by using the net primary productivity model of integrated natural vegetation and residual analysis method,and on the basis of it,the correlation between climatic factors and elevation and annual variation and spatial distribution of NPP were analyzed.The results showed that：（1）The average NPP of the study area from 2005 to 2015 was 286.6 gC/m2,the NPP was fluctuating,and the grassland generally presents a tendency of slow degeneration.（2）The relative contribution rates of climate,human activity and the combination of the two to grassland change were 26.5%,61.1%and12.4% respectively,human activity was the main driving force of grassland degradation,and climate and human activity were the leading factor in the grassland restoration.（3）NPP changes were positively related to the annual average temperature and sunshine duration,and were negatively related to elevation and rainfall,the annual precipitation of the NPP was the most significant.