三大自然区过渡带生境质量时空差异及形成机制——以榆中县为例

以地处三大自然区过渡地带的榆中县为案例,分析了1995-2015年县域及内部分区生境质量演变的时空特征,借助地理探测器模型分析并探索了生境质量影响因素及其机制。结果表明：① 全县生境质量变化保持稳定并略有提升,县域内部生境质量变化呈现出由南向北递减的三级梯度特征;② 全县生境质量的地带间与地带内差异均趋于缩小,北部黄土高原区持续加大,中部平原区连续下降,南部山区则先缩小后增大;③ 全县及县域内部的影响因素及机制因为地理尺度的差异而不同。自然环境变量对生境质量变化发挥着基础和关键性的作用,社会经济变量呈现出减小的态势,而政策调控变量对生境质量的影响则越来越大,各因子间的协同增强效应推动了生境质量的变化。

Spatio-temporal variation on habitat quality and its mechanism within the transitional area of the Three Natural Zones:A case study in Yuzhong county

Habitat quality is an important proxy for the service level of a biological system, and is also critical for the maintenance of regional ecological security and human wellbeing. Evaluating the spatiotemporal variations that result from land use changes can therefore provide the scientific basis for regional ecological protection and land management. Thus, taking Yuzhong County as a case study, which is located in the transitional area of the Three Natural Zones, this paper examines the spatiotemporal characteristics of habitat quality and its evolution over the period between 1995 and 2015 based on coefficient of variation and Taylor index. Choosing 14 explanatory variables, such as rainfall, distance to the county center, and area of land remediation, this paper explores by means of geographic detector analysis the factors that influence habitat quality and its evolution across a range of different spatial levels. The results of this analysis reveal that, in the first place, habitat quality throughout the whole county has remained stable and has improved slightly over the last 20 years. However, due to variations in natural and socioeconomic conditions, internal changes in habitat quality within the three sub-regions considered in this study are different from one another, consistent with an overall decrease along a south-north transect. Secondly, the differences in habitat quality between the three regions, as compared to the differences within them, have tended to decrease over time. Over the period of this analysis, variations in habitat quality continued to increase on the Loess Plateau in the north, declined continuously in the Middle Plain Area, and initially descended then ascended in the Southern Mountain Area. Thirdly, geographic scale is an important component that must be considered for evaluating habitat quality changes, as factors and mechanisms vary at different levels. Natural environmental variables play a fundamental role in habitat quality changes; on the other hand, the effect of socioeconomic variables on habitat quality has become weaker over time, whereas the effect of policy variables has become greater. Furthermore, synergism occurs amongst the different factors. Considering the importance of different policies based on different geographical scales, this paper proposes relevant policy suggestions for optimizing habitat quality within comparable areas.