Guan Xiao: Climate change significantly affects ecological security in the Wujiang River Basin

Wujiang River is the largest river in Guizhou. 80% of its drainage basin is in Guizhou Province, accounting for 40% of the province's administrative area. The Wujiang River is an important ecological barrier in the upper reaches of the Yangtze River and an important channel for the four provinces of Yunnan, Guizhou, Chongqing and Hubei to integrate into the "Yangtze River Economic Belt". However, the ecological environment of the Wujiang River Basin is fragile, and global climate change has increased the ecological vulnerability of the Wujiang River Basin. In this context, how to protect the Wujiang River Basin ecosystem? At the ecological and environmental protection exchange meeting in the upper reaches of the Yangtze River recently held by the Yangtze River Ecological and Environmental Protection and Restoration Joint Research Center (hereinafter referred to as the Yangtze River Center), the reporter interviewed the person in charge of the Guizhou Provincial Resident Tracking Research Working Group for the Yangtze River Ecological and Environmental Protection and Restoration Joint Research, Guan Xiao, senior engineer at the China Academy of Environmental Sciences.

China Environment News: What is the current ecological environment status of the Wujiang River Basin?

Guan Xiao:Relying on the joint research on ecological and environmental protection and restoration of the Yangtze River, the Guizhou Provincial Resident Working Group carried out relevant research on the ecological and environmental conditions of the Wujiang River Basin, and analyzed the ecological vulnerability, rocky desertification degree, and water and soil in the Wujiang River Basin during the 20 years from 2000 to 2020. Conservation ability. Taking 2010 as the boundary, the ecological vulnerability of the Wujiang River Basin showed an increasing trend in the first 10 years, especially in the downstream areas, where the ecological vulnerability increased significantly; in the next 10 years, the ecological vulnerability of the Wujiang River Basin showed a downward trend, and the vulnerability of the upstream areas decreased significantly. In terms of the degree of rocky desertification, the degree of rocky desertification in the Wujiang River Basin showed an increasing trend in the first 10 years; the degree of rocky desertification generally decreased in the next 10 years. In terms of soil and water conservation capabilities, soil conservation capabilities were basically stable in the first 10 years; soil conservation capabilities increased significantly in the next 10 years, and growth areas were concentrated in the upstream and downstream areas.

In addition, we conducted a comprehensive evaluation of ecosystem services in the Wujiang River Basin from 2000 to 2020. Judging from the spatial pattern of the average values of the six ecosystem services, the downstream provides more ecosystem services, followed by the middle reaches, and the upstream reaches less; judging from the spatio-temporal change pattern, the downstream ecosystem services increase the most, and the midstream ecosystem services decrease the most. Since Guiyang City and Zunyi City, which have relatively good economic development in Guizhou Province, are mainly concentrated in the middle reaches, from the perspective of ecosystem services, the middle reaches are in a downward trend. From the perspective of spatial analysis, the ecosystem service clusters in the lower reaches of the Wujiang River are mostly ecologically excellent and water conservation types, while the upper reaches are mostly water-consuming types. Research on ecosystem service clusters shows that downstream areas have stronger ecosystem service capabilities. In the spatial pattern, the "trade-off/synergy" relationship between ecosystem services in the five periods from 2000 to 2020 has basically remained relatively stable. Through identification research, it is concluded that the main factors affecting ecosystem services in the Wujiang River Basin are climate and natural surface factors, as well as human activities.

In the 2018 Wujiang River Basin Biodiversity Survey, a total of 561 plant species were found. By studying the interrelationship between ecosystem services and biodiversity, it is found that water supply and water conservation have a stronger impact on biodiversity. Except for food supply, all ecosystem services are positively correlated with biodiversity.

Referring to the "Technical Guidelines for Investigation and Evaluation of River Ecological Security"(GB/T 43474-2023) issued by the Ministry of Ecology and Environment, 22 evaluation indicators have been constructed from three aspects: water ecological environment pressure, water ecosystem health, and water ecological service functions. The evaluation indicator system including indicators conducted a comprehensive assessment of ecological security in the Wujiang River Basin. The evaluation result was 53.59 points, which was a "general" level.

In addition, we evaluated the current status of aquatic life in the Wujiang Basin with reference to the "Technical Guidelines for Water Ecological Monitoring, River Aquatic Life Monitoring and Evaluation (Trial)"(HJ 1295-2023). The results showed that the Wujiang River Basin was at a "medium" level as a whole, and there were seasonal differences in the evaluation results of different biological indices; the overall evaluation results in spring were better than those in autumn. In terms of the current status assessment of the water ecological assessment pilot, the number of fish species, natural shoreline rate and ecological flow compliance rate have reached the "excellent" level; the number of key protected aquatic organisms is 3, and the expected value of Wujiang (Guizhou section) is 4, classified as "good" level; the number of macrobenthos species and comprehensive pollution status are classified as "good" level; the comprehensive assessment results of water connectivity and watershed ecological security are "general" level. The aquatic biological evaluation results show that the Guizhou section of the Wujiang River Basin is generally at a "medium" level.

China Environment News: What impact does climate change have on the ecological environment of Guizhou, especially in the Wujiang River Basin?

Guan Xiao:In the research, we explored the driving effect of different social and economic development models on climate change by simulating scenarios under different social development methods and carbon emission models. We have set up three paths. The first is a green and sustainable development path, which in layman's terms is a green and low-carbon development model; the second is a path representing a medium-level greenhouse gas emissions, which means following the middle path and technological development of economy and society., greenhouse gas emissions are at a medium level; The third is the high-end forced path, which in layman's terms is an extensive development model, characterized by resource-intensive rapid development and material-intensive consumption models, as well as very high levels of fossil fuel use and high greenhouse gas emissions.

Through prediction analysis, it is found that water supply shows an increasing trend to varying degrees. From a spatial perspective, the spatial distribution of water supply in the three paths is generally consistent, showing the spatial distribution characteristics of "high in the north and low in the south". The high-value area of water supply in the sustainable development path accounts for more than 50% of the total area.

By analyzing carbon reserves and water conservation, it is found that the carbon reserves of the third path show a downward trend due to the extensive development of high energy consumption. From a spatial perspective, whether it is carbon reserves or water conservation, the high-value areas are mainly distributed in the lower reaches of the Wujiang River Basin; among the three paths, the sustainable development path has the highest total carbon reserves, followed by the medium-level path and the total amount of water conservation. lowest.

In terms of habitat quality and soil conservation, under the sustainable development path, the comprehensive supply capacity of ecosystem services (that is, the two supply capabilities of habitat quality and soil conservation) is significantly stronger than that of intermediate-level paths and high-end forced paths. This suggests that sustainable social and economic development and low levels of greenhouse gas emissions can help improve regional ecosystem services.

In terms of biodiversity, in different climate change scenarios in the future, biodiversity will increase to varying degrees under both the sustainable development path and the intermediate-level path, with the former increasing most significantly; From a spatial perspective, the spatial distribution of biodiversity in the three paths is generally consistent. Biodiversity in national nature reserves such as Fanjing Mountain, Mayang River, Jinfo Mountain, Dashe River, and Xingdoushan are all high, which is sustainable. In the development path scenario, biodiversity around Guiyang City has decreased less.

Since the Wujiang River Basin is a typical karst area, climate change will have a significant impact on the region's fragile ecological environment. Specifically, it includes: Rising water temperature affects changes in the biological processes, species composition and food web of aquatic organisms; water stratification and reduced dissolved oxygen content will increase the nutrient load of the water body and promote changes in the plankton algae population in the water body; changes in water temperature will also change the growth conditions of aquatic plants, biomass and distribution, affect the survival, growth and development of fish in the water body, and changes in habitat, resulting in a decrease in the number of aquatic invertebrates; The increase in extreme weather such as heavy rainfall can easily cause soil erosion, organic matter and soil flow into water areas, and damage the aquatic ecological environment.

China Environment News: Regarding the current ecological environment situation in the Wujiang River Basin, what work needs to be done in the future?

Guan Xiao:In the next step, we will follow the relevant work requirements of the Ministry of Ecology and Environment, with the strong support and guidance of the Yangtze River Center, combine the first and second phase of the on-site follow-up research work in Guizhou Province, and based on the actual status of the Wujiang River Basin terrestrial ecosystem, we will mainly consider the following aspects: Carry out relevant research on the strategies of terrestrial ecosystems to respond to climate change.

First, vigorously promote energy conservation and emission reduction, promote clean production, reduce dependence on fossil energy, reduce greenhouse gas emissions, and continuously improve the level of green and low-carbon development. The second is to promote sustainable water resources management and optimize water resources allocation. Promote water-saving irrigation technology and industrial water recycling to reduce ecological problems caused by uneven distribution of water supply upstream and downstream in the Wujiang River Basin. The third is to strengthen the protection of existing forests and wetlands and implement ecological restoration projects. Protect existing forests and wetlands and maintain biodiversity by establishing nature reserves and ecological corridors. At the same time, ecological restoration projects such as vegetation restoration and rocky desertification control are carried out in damaged areas to enhance the ecosystem's regulatory service capabilities such as carbon sequestration and water conservation. The fourth is to establish a climate change monitoring network. Build a meteorological, hydrological and ecological monitoring network in the Wujiang River Basin to monitor climate change and its impact in real time. The fifth is to improve the early warning and forecasting system. Strengthen the construction of early warning and forecasting systems for extreme weather events, improve prediction accuracy, release early warning information in a timely manner, and reduce disaster losses. Sixth, strengthen climate change adaptability and build flood control and drought relief facilities. Strengthen the construction and maintenance of flood control and drought relief facilities such as dams, reservoirs and drainage systems to improve the ability to respond to extreme weather events.