时空信息熵在延河流域生态可持续性分析中的应用

视流域为一个有生命力的不可分割的有机整体,为表征其生态可持续性,从熵的视角出发,提出结合空间信息熵和时间信息熵的时空信息熵方法。其中空间信息熵用于表征生态系统格局在空间分布的有序程度,时间信息熵用于度量生态系统的动态演变是否有序,时空信息熵方法将格局和动态有机结合,定量分析流域生态系统的可持续性。以延河流域为研究区,基于土地利用数据和归一化植被指数数据,利用时空信息熵方法分析2000-2018年延河流域生态可持续性。结果表明:(1)延河流域生态系统格局朝着有序的方向变化,此间整体处于生长期或恢复期;(2)时间信息熵结果呈现空间异质性,耕地、中低覆盖度草地和其他林地的时间信息熵值较高,生态弹性能力更强;(3)研究区生态可持续性以"强"和"较强"为主(61%),广泛分布在其中部和北部地区,表明流域的生态弹性能力总体增强,生态可持续状况明显改善。对基于熵视角研究生态可持续问题的有益探索,为延河流域及黄土高原其他类似流域的生态保护和修复提供借鉴和参考。

Spatio-temporal information entropy for the analysis of ecological sustainability and its application in the Yanhe watershed

Regarding watershed as an indivisible organic whole with self-organizing capability, in order to characterize its ecological sustainability, the spatio-temporal information entropy method combining spatial information entropy and temporal information entropy was proposed from the perspective of entropy. The spatial information entropy was used to characterize the order degree of ecosystem pattern in spatial distribution, and the temporal information entropy was used to measure whether the dynamic evolution of ecosystem was orderly or not. The spatio-temporal information entropy method analyzed the sustainability of watershed ecosystem quantitatively by combining pattern and dynamics. Taking Yanhe watershed as the study area, based on three-period land use data and long time series Normalized Difference Vegetation Index (NDVI) data, the ecological sustainability of Yanhe watershed from 2000 to 2018 was analyzed using the spatio-temporal information entropy method. The results showed that: (1) the ecosystem pattern of the Yanhe watershed changed in an orderly direction, indicating that the Yanhe watershed was in the growth or recovery period as a whole. (2) The distribution of temporal information entropy showed the spatial heterogeneity. The temporal information entropy values in the south and southwest of the study area were the lowest, while the values of the north and central were higher, and the values in the northwest and southeast were the staggered distribution. The temporal information entropy values of the cultivated land, middle and low coverage grassland and other woodland were higher than others, so the ecological resilience of these vegetation types was stronger. The pattern of cultivated land with middle coverage grassland could be adopted in the future. (3) The ecological sustainability was mainly strong and less strong (totally 61%), most of which were distributed in the central and northern regions, indicating that the ecological resilience capacity of Yanhe watershed was mostly enhanced and the overall situation of ecological sustainability was significantly improved. The proportion of weak and less weak was the lowest (totally 13%), which was concentrated in the northwest and south ends of the basin, and the ecological sustainability of these regions still needed to be further improved. Specific ecological management measures were formulated for different grades of regions. This research is a useful exploration for the study of ecological sustainability from the perspective of entropy, which provides a new perspective with interdisciplinary characteristics for the study of ecological sustainability, and can be a reference for the ecological protection and restoration of Yanhe watershed and other similar watersheds in the Loess Plateau.