Geoinformation analysis of changes in indicators of Almaty city’s forests fragmentation

Abstract

Large forests areas of the Ile-Alatau State National Natural Park were annexed to the Almaty city due to expansion of its borders in 2012. The floral composition of these forests is represented by many species, among which are rare and endemic ones. The recreational pressure on forest lands after joining to the territory of the city has increased significantly and the most common consequence of this became the fragmentation of forests, i.e. their dismemberment into sections by various boundaries (construction, road transport infrastructure, etc.). Forests fragmentation leads to degradation and even death of forest communities, as well as to a decrease in their ecosystems functions. These changes of the suburban forests lead to a deterioration in the comfort parameters of the urban environment and a decrease in the quality of life of the population. The quantitative assessment of changes in the degree of fragmentation of Almaty city’s forests was carried out in the work, based on the geoinformation analysis and mapping methods. The calculation of a number of indices describing such features of the territorial organization of forests that can have a significant impact on the effectiveness of their environment protection functions was laid as the basis: forest cover index (FC), Mean Patch Size (MPS), Mean Shape Index (MSI), Edge density (ED) and Mean Nearest Neighbor (MNN). The indices were calculated for 9 river basins from 2014 to 2020 and the results were used to create a series of corresponding maps and a comparative table of changes in fragmentation indicators over the study period. The analysis of the calculated indices revealed patterns of dynamics of the fragmentation’s degree of Almaty city’s forests depending on the level of economic development, intensity of recreational pressure and proximity to major highways. Thus, the highest rates of fragmentation are characteristic of the catchments of the Shirokaya Shchel, Solonovka and Malaya Almatinka rivers. Comparison of fragmentation indices for 2014 and 2020 showed that, in general, the entire territory of the Ile-Alatau National Park is characterized by a slight, but deterioration in the indicators of forests fragmentation. The most significant deterioration was noted for the basin of the Bolshaya Almatinka River and its tributary the Kumbel River, where an extensive recreation area was formed, as well as in the basin of the Malaya Almatinka River and its tributary the Butakovka River. The indices of fragmentation of woodlands in the basin of the Kazashka River deteriorated to the least extent.