基于遥感总初级生产力的天山-塔里木绿洲地区生态系统脆弱性研究

Ecosystem vulnerability in the Tianshan Mountains and Tarim Oasis based on remote sensed gross primary productivity

生态系统的脆弱性是全球气候变化与可持续发展研究的核心问题,测定与评价脆弱性对认识生态系统的结构与功能至关重要。天山-塔里木绿洲地区包含着山地、荒漠和绿洲等多种类型的生态系统,存在着多个不同生态类型的交界过渡区。为定量评价该地区生态脆弱性,以植被总初级生产力这一生态系统重要的功能性指标为基础,对该地区生态系统脆弱性进行了计算和分级(不脆弱、轻度脆弱、中度脆弱、重度脆弱和极度脆弱),并对研究区生态系统脆弱性的空间分布特征及其与环境因子的关系进行了分析与讨论。结果表明:(1)研究区生态系统脆弱性总体上表现出明显的空间分化格局,以中度和重度脆弱为主,极度脆弱的地区主要分布在南部的塔里木绿洲。(2)生态系统脆弱等级大体上随着区域内多年平均温度的升高而升高。受地表水灌溉的影响,生态系统脆弱性与降水量间并无明显趋势性规律。(3)研究区的生态系统脆弱等级随着区域内的平均海拔以及平均坡度的升高都呈现下降的趋势。受自然条件恶劣、过度放牧以及农田过度开垦的影响,目前该地区总体呈现脆弱性严重的状态。研究表明该地区应积极开展生态治理工作,合理规划生态功能关键区,保护好现有草原和湿地等易开垦地区,划定绿洲开发范围的"红线",限制农田的开垦,协调好塔里木河流域的水资源分配。研究为使用卫星遥感数据研究生态系统脆弱性提供了方法上的参考,为可持续发展和生态治理提供了科学依据。

Ecosystem vulnerability is a core issue of global climate change and sustainable development research.Measuring and evaluating of vulnerability are essential for understanding the structure and function of ecosystems.Tianshan-Tarim Oasis contains multiple types of ecosystems such as mountain,desert and oasis,and there are many ecotones between different ecological types.Gross primary productivity(GPP)of vegetation,which is the total amount of carbon uptake by vegetation photosynthesis,is an important functional indicator of terrestrial ecosystem.GPP is not only an important index to measure the health status of ecosystem,but also a result of comprehensive effects of the environmental limiting factors on ecosystem.The fluctuation of vegetation productivity can also be used as an indicator to measure the vulnerability of ecosystem.In this study,GPP products with a spatial resolution of 1 km retrieved from Moderate-resolution Imaging Spectroradiometer(MODIS)were chosen to calculate and evaluate the ecosystem vulnerability of the study area.Based on vegetation productivity,the vulnerability of the study area is calculated and classified into not vulnerable,mild vulnerable,moderate vulnerable,severe vulnerable,and extreme vulnerable.The spatial distribution characteristics of ecosystem vulnerability and its relationship with environmental factors were also analyzed and discussed.The results showed that:(1)the ecosystem vulnerability of the study area presented an obvious spatial differentiation pattern on the whole,with moderate and severe vulnerability as the main feature,and the extremely vulnerable areas were mainly distributed in the southern Tarim Oasis;(2)the vulnerability of the ecosystem generally increased with the rise of the mean annual temperature in the region.Affected by surface water irrigation,there was no obvious trend between ecosystem vulnerability and precipitation;(3)the vulnerability of the ecosystem in the study area indicated a downward trend with the increase of the average altitude and the average slope in the area.Due to harshly natural conditions,overgrazing and over-exploitation of farmland,the area currently showed a state of serious vulnerability.Therefore,the ecological governance should be actively carried out,the key areas of ecological functions should be rationally planned,grassland,wetland and other easy-to-reclaim areas should be protected,the red line of the scope of oasis development should be delineated,farmland reclamation should be restricted,and the distribution of water resources in the Tarim River Basin should be coordinated.This study provides a methodological reference for using satellite remote sensing data to study the vulnerability of ecosystems,and provides a scientific evidence for sustainable development and ecological governance.