Ye Yuan

Riparian forests in the valley area of the Irtysh River Basin are capable of providing a variety of ecosystem services such as water conservation and biodiversity maintenance. Their health condition is an important reflection of their ability to maintain the stability of ecosystem structure and perform ecosystem functions. In this study, a comprehensive survey was conducted to observe the typical distribution areas of riparian forests in the valley of six tributaries and one main stream of the Irtysh River Basin. Twelve indicators were chosen from the three categories of vigor (i.e., productivity), organization (i.e., species diversity and structure complexity), and resistance (i.e., harmful factors and disturbances) to form an evaluation system. Expert-based and statistical weighting were applied to calculate the health scores of riparian forests in the valley and prioritized the health grades of seven rivers. Several criteria were used to further classify the unhealthy level of each river individually. The results of this study can be used as a foundation for future conservation and orderly development of riparian forests in the valley area. The results show that (1) the Kuyertes River was classified as healthy, while the Haba and Berezek Rivers were classified as unhealthy. (2) Among the three evaluation categories, the organization consistently achieved higher scores compared to vigor and resistance. (3) Unhealthy conditions were consistently observed in the midstream sections of each river. (4) Forest types such as Salix alba L. forests, Populus euphratica Oliv. forests, and Betula pendula Roth forests were particularly prone to poor health outcomes. The health of the riparian forests was relatively unsatisfactory due to the conflicting water resource allocation. The protection and restoration of riparian forests in the valley area of the Haba and Berezek Rivers should be prioritized in the future, as well as the middle reaches of each tributary. Additionally, it is necessary to pay attention to three key indicators: stand volume per unit area, stand density, and diameter at breast high (dbh) class structure to improve the health condition of riparian forests.

Arid areas are faced with frequent droughts and sandstorms, and through variations of the harsh natural conditions. Urban green space is an important ecological infrastructure to improve the harsh climate, but green space system planning often exposes strong subjectivity. The suitability evaluation of urban green space can be based on the powerful spatial analysis capabilities of GIS, through investigation and comprehensive analysis of the suitability of the land for various uses, the level of quality and its restriction status, etc., so as to classify and grade the ecological functions of urban green space. Taking Beitun city in Xinjiang Province as an example, according to local conditions, evaluation factors were selected from five aspects: wetland resources, flora and fauna habitat, landscape features, anthropogenic disturbance and temperature risk; the factor weights were determined by analytic hierarchy process; a green space suitability evaluation system based on three levels of “target-criterionindex” was established, and on this basis. Using the GIS spatial overlay analysis module, five levels of urban green space ecological suitability zones were delineated: the most suitable green area (23.6%); the high-suitability area (32.1%); the mid-suitability area (21.6%); the low-suitability area (14.5%); and the unsuitable area (8.2%), Combined with the current situation of land use and the demand of urban development in Beitun city, the functional zoning of urban green space ecological facilities are divided into a green ecological restoration area, a green ecological conservation area, low-and medium-impact development areas and a green suitable development area; on a scientific basis, allocation of green space resources and protection countermeasures are proposed to construct green space in each area as part of the theoretical guidance for Beitun. The results show that appropriate indicators and methods can more accurately reflect the actual and demand of urban green space development in arid areas, and play a practical guiding role. The research provides a useful attempt and supplement for the practice and application of the method of division of green space ecological suitability in arid cities.