内蒙古生态系统质量空间特征及其驱动力

植被作为生态系统的重要组成部分,联结着大气、水分和土壤等自然过程,其变化将直接影响该区域气候水文和土壤等状况,是区域生态系统质量变化的重要指示器。植被状况的好坏,主要通过生物量和植被覆盖度因子来表示。内蒙古自治区是我国北方生态环境问题十分严重的省份,弄清当前区域生态系统质量状况与变化及其近10年来变化的驱动因素,对分析与制定区域生态环境保护决策具有十分重要的意义。基于2000—2010年生物量和植被覆盖度,并结合地区植被区划数据,对内蒙古植被生态系统质量状况进行分析,并评估其与气候(降水、温度),人类活动(交通密度、农业发展、生态恢复工程)的相关关系,在此基础上探讨了气候和人类活动对近年来内蒙古生态系统质量变化的影响。结果表明:(1)内蒙古生态系统质量状况整体偏低,其中森林生态系统平均质量最高,灌丛、草原生态系统次之。空间分布呈明显的经度地带性,由东向西,质量逐渐降低。2000—2010年内蒙古生态系统质量总体上呈现缓慢增长趋势,但局部地区生态系统质量仍存在恶化,其中在107°E以东的草原和森林区域,生态系统质量变化十分剧烈。(2)近10年来内蒙古生态系统质量的变化与气候和人类活动的关系非常密切,其与降水、GDP1、化肥施用量、天保工程和退耕还草工程呈现明显的正相关。而与温度、道路密度和京津风沙治理工程呈现明显的负相关。其中,生态保护工程实施区域内和区域外的相关性存在显著的差异性。随着内蒙古社会经济的快速发展,人类活动对生态系统质量的影响逐渐加强,但降水仍是该地区生态系统质量的主要影响因子。(3)在内蒙古生态系统质量变化典型区域内,质量的增长主要是由于降水的增加、温度的降低、农业的发展、退耕还草工程的作用和交通发展的放缓。质量的降低则是因为降水的减少、温度的增加、农业发展缓慢和交通发展的加快所致。

Spatial patterns of ecosystem quality in Inner Mongolia and its driving forces analysis

Vegetation is an important component of ecosystems, and it is involved in natural processes such as regional climate circulation, the hydrologic cycle, soil conditions, and other natural processes. It is also an important indicator of regional ecosystem quality change. Aboveground biomass and vegetation cover are important variables for describing vegetation quality and documenting ecosystem changes. Moreover, they are controlling factors in transpiration, photosynthesis, and other terrestrial processes, and are sensitive indicators of land degradation and desertification in arid and semi-arid regions. Aboveground biomass and vegetation cover have been used widely in the analysis of vegetation quality and changes. Inner Mongolia, an important province of northern China that is located mostly in arid and semi-arid areas, is undergoing a process of significant warming and drying, which could lead to serious ecological problems such as land degradation and desertification. Determining the driving cause of these problems has become a focus of vegetation research. Many researchers have attributed the degradation and desertification in northern China to long-term over-grazing, extensive cutting, and widespread conversion of grassland to cropland. Other studies have found that poor climate conditions, such as drought, severe wind erosion, temperature fluctuation, and winter precipitation are the primary cause of degradation and desertification. Nevertheless, some recent studies have shown that human activities can control the degradation in selected study regions of northern China. It is necessary to investigate current ecosystem quality and its response to climatic variation and human activities for a better understanding of the accumulated consèquences of changes in climate and human activities. In this study, combining remote sensing products (aboveground biomass and vegetation cover) with vegetation regionalization data, we quantified ecosystem quality in Inner Mongolia, and analyzed the effects of climate and human activities on spatial variations in quality change from 2000 to 2010. Our results indicated that overall ecosystem quality in Inner Mongolia is very low. Among the ecosystem types, the highest quality was exhibited in forest ecosystems, followed by shrub and grassland ecosystems, respectively. Ecosystem quality displayed evident spatial heterogeneities, divided according to latitude, and reduced gradually from east to west. There was a slight increase in ecosystem quality over the study period. However, degradation and desertification also existed in some regional areas. The spatial variation characteristics of ecosystem quality are formed by interactions between the influencing factors. The partial correlations among ecosystem quality and precipitation, GDP1, fertilizer, the natural forest protection project, and the returning farmland to grassland project were positive and statistically significant. By contrast, ecosystem quality was negatively correlated with temperature, road density, and the treatment of sand and wind sources. With the rapid development of the social economy of Inner Mongolia, the influence of human activities on ecosystem quality gradually increased, but precipitation was still the dominant factor that influenced the spatial variation characteristics of ecosystem quality. The main reasons for the improvement of ecosystem quality in a typical area were increasing precipitation, decreasing temperature, development of agriculture, returning farmland to grassland, and a slowing of traffic development. In addition, decreasing precipitation, increasing temperature, a slowdown of agricultural development, and a speeding up of traffic development led to degradation and desertification. These results provide specific information that may serve to strengthen the necessary public awareness about protecting and restoring ecosystems.