Study On Reasonable Target Of Vegetation Restoration And Potential Improvement Of Carbon Sequestration In A Water Conservation Area Of The Upper Yellow River Basin

In the past few decades,China’s ecological environment has significantly improved through large-scale vegetation restoration projects.However,the issue of vegetation restoration not matching natural conditions in some areas is increasingly evident,posing new challenges for current and future ecological sustainable development.In this context,it is urgently needed to scientifically and reasonably set vegetation restoration goals for different spatial units,considering the differences in the degree of damage to regional ecosystems and the heterogeneity of natural conditions.At the same time,assessing the potential improvement of carbon sequestration under the ecological restoration measures and future climate change,developing feasible restoration strategies,and fully utilizing the carbon sequestration benefits of vegetation restoration have important practical significance for promoting the realization of the"dual-carbon"goal.The water conservation area of the upper Yellow River basin is a key region for ensuring the ecological security of the middle and lower reaches of the Yellow River.Doing a good job of ecological protection and vegetation restoration in this area is of great significance to improving and enhancing the ecological system function of the Yellow River basin and even the whole country.This study utilized the IBIS_i model（Integrated Biosphere Simulator）to simulate the potential net primary productivity（NPP）of vegetation in the water conservation area of the upper Yellow River basin at a kilometer scale firstly.The reliability of the model-driven data and simulation results was verified through sample testing.Based on this,from the perspective of enhancing carbon sequestration capacity,this study evaluated the reasonable target of vegetation restoration in the study area during the current period（2011–2020）,identified key restoration areas,and proposed restoration strategy recommendations for zonally-classified regions.Considering the adjustment of target under future climate change,this study further predicted the reasonable targets of vegetation restoration and the potential improvement of carbon sequestration for the short-term future（2021–2030）and long-term future（2031–2060）in the research area and analyzed their dynamic changes.The main conclusions are as follows:（1）The actual NPP in the water conservation area of the upper Yellow River basin showed an east-high-west-low spatial distribution pattern.From 2000 to 2020,the actual NPP in the research area showed an overall fluctuating increasing trend,especially in the low-altitude areas in the eastern part of the research area,the Gonghe basin in the central part,and the junction of the northern part with the Qinghai Lake basin where the growth rate was faster.The areas where the actual NPP showed a decreasing trend were mainly scattered in the region from the source of the river to Maqu hydrometric station,and this mainly occurred after 2010.（2）Currently,the average vegetation net primary productivity restoration target value in the water conservation area of the upper Yellow River basin is 295.4 g C·m^-2·a^-1,which can be restored and improved by 7.18%based on the baseline period.The proportion of areas with potential improvement of carbon sequestration in the research area is about 60%,mainly distributed in the areas above Longyangxia reservoir and the Taohe–Daxia river basin.It is recommended that the water conservation area of the upper Yellow River basin should focus on conservation and natural restoration.In some areas above the Jimai hydrological station on the north bank of the Yellow River,the Gonghe basin,the Longyangxia reservoir area,the Guinan sand,and the Yellow river–Huangshui river valley,vegetation restoration assisted by human intervention should be implemented.（3）In the near-term,regardless of whether in the SSP1-2.6 or SSP5-8.5 scenarios,the carbon sequestration capacity of vegetation in the water conservation area of the upper Yellow River basin shows an upward trend.By 2030,under the SSP1-2.6 scenario,the vegetation restoration target in the research area will decrease from the current 295.4g C·m^-2·a^-1 to 283.36 g C·m^-2·a^-1,and the average potential improvement of carbon sequestration will be 7.56 g C·m^-2·a^-1.Under the SSP5-8.5 scenario,the average vegetation restoration target in the research area will be 328.68 g C·m^-2·a^-1,which is an11.27%increase over the current target,and 16%higher than the SSP1-2.6 scenario,with an average potential improvement of carbon sequestration of 52.93 g C·m^-2·a^-1.（4）In the long-term,the overall carbon sequestration capacity of vegetation in the water conservation area of the upper Yellow River basin continues to show an upward trend.The growth rate accelerates especially after 2040,but there are regional differences in different river basins,and the carbon sequestration capacity of vegetation in the Taohe–Daxia river basin shows a decreasing trend.By 2060,under the SSP1-2.6scenario,the average vegetation restoration target in the research area will be 358.97g C·m^-2·a^-1,which is an increase of 21.52%over the current target,with an average potential improvement of carbon sequestration of 83.25 g C·m^-2·a^-1.Under the SSP5-8.5 scenario,the average vegetation restoration target in the research area will be 404.33g C·m^-2·a^-1,which is an increase of 36.88%over the current target and 12.64%higher than the SSP1-2.6 scenario,with an average potential improvement of carbon sequestration of 128.53 g C·m^-2·a^-1.