Biodiversity is the basis for the maintenance and functioning of ecosystems. Genetic diversity is at the heart of biodiversity, and therefore an understanding of the current state of plant genetic diversity can contribute to the future provision of sustainable ecological values and services by ecosystems. This study was conducted in the Irtysh River basin (five tributaries) with the dominant species of river valley forests, Betula pendula. Sampling points were set up at approximately 10 km intervals within each tributary using a random sampling method for genetic diversity studies based on chloroplast microsatellite molecular markers. The results indicated that (1) nine alleles were identified in 198 samples. The genetic diversity of Betula pendula was relatively rich in all tributaries (I = 0.216~0.546); genetic diversity was significantly higher in the downstream area of the basin than in the midstream and upstream areas of the basin. Genetic differentiation was at a low level in the tributaries except for the Berezek River, where genetic differentiation was high. (2) Genetic variation was mainly derived from within populations, accounting for 62% of the total genetic variation. The genetic distance was significantly positively correlated with the geographical distance (p < 0.05). The Betula pendula population structure was divided into two major groups. (3) Twelve haplotypes were identified in the basin. The dominant haplotypes in the upper tributaries were H2 and H4, while in the lower tributaries these were H1 and H3. Therefore, this paper suggests the future establishment of a germplasm resource bank for populations of the Berezek River, and the implementation of priority conservation measures for the downstream populations with higher genetic diversity, so as to realize the sustainable ecological value of the valley forests of the Betula pendula.

The river valley forests of the Irtysh River Basin are a germplasm bank of Salicaceae species and rare plant resources in China, and the distribution varies with the river and is highly distinctive. However, there is a dearth of systematic research on the characteristics of plant resources. In this study, a comprehensive investigation was conducted in the trunk stream and six tributaries with valley forest distribution in the Irtysh River Basin, and 244 quadrats were set up. The analysis focused on the composition of the flora and resource characteristics. The results reveal the following: (1) The valley forests of the Irtysh River Basin contain 256 species of plants belonging to 57 families and 178 genera, among which 19 species of trees, 23 species of shrubs, and 214 species of herbs were investigated. (2) Among the identified species, 226 (88.67%) were recognized as resource plants, with medicinal plants being the most abundant (176 species, 68.75% of the total). (3) The distribution patterns of trees, shrubs, and herbs of each resource type vary across rivers. Elevation drop, river length, and river distance all significantly affect the number of specie. This study elucidated the current status and distributional characteristics of plant resources in the valley forests of the Irtysh River Basin, which is essential for both biodiversity conservation and sustainable resource utilization.

The Irtysh River, which stretches for 633 km, is the second longest river in Xinjiang. The valley forests within its basin are unique forest resources that exhibit crucial ecological functions and form an integral part of China’s “Three North” Shelterbelt Forest Project. However, previous studies mainly focused on individual tributaries or main streams, lacking comprehensive research on the overall river and valley forest resources and their ecological functions. To address this research gap based on comprehensive investigations, this study analyzed the dominant species composition, spatial distribution patterns, and influencing factors of valley forests across various branches of the Irtysh River basin plain. The results revealed the presence of 10 local tree species in the area, with Populus laurifolia, Populus alba, Salix alba, and Betula pendula as the dominant species. However, seedling regeneration was relatively weak. P. laurifolia, P. alba, and S. alba were widely distributed across tributaries and main streams, whereas B. pendula was primarily found in the tributaries. The four dominant species exhibited distinct clustering patterns. The concentration intensity of these dominant species in the main stream of the Irtysh River basin was significantly higher than those in other tributaries, with P. laurifolia showing a lower concentration intensity across the entire basin than the other dominant species. Negative density dependence was the primary biological factor influencing species aggregation intensity, with significant positive effects on P. alba and S. alba and significant negative effects on B. pendula. Among the abiotic factors, elevation had a significant positive effect on the aggregation intensities of P. alba, S. alba, and B. pendula, indicating that these species tend to aggregate more densely at higher elevations. Conversely, slope had a significant negative impact on the aggregation intensities of P. laurifolia, P. alba, and S. alba, suggesting that increasing slope steepness leads to a decrease in the clustering of these species. Similarly, the distance from the river channel had a significant negative effect on the aggregation intensities of S. alba and B. pendula, implying that as the distance from the river increases, the clustering patterns of these species become less pronounced. This study aimed to detail the current state of valley forest resources and their ecological functions, thereby laying a foundation for their effective protection.

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.