Impacts of ecological restoration projects on the ecosystem carbon storage of inland river basin in arid area, China

As an important means to cope with global climate change, ecological restoration projects have a huge impact on ecosystem carbon storage functions. Scientifically evaluating the response process and mechanism of basin ecosystem carbon storage functions in ecological restoration projects is beneficial to the improvement of regional ecosystems. Taking Shiyang River Basin (SRB) as an example, and based on the perspective of "carbon sink-carbon source" mutual transformation, the current study utilized the InVEST (Integrated Valuation of Ecosystem Services and Tradeoffs) model to analyze the spatio-temporal dynamics of carbon storage in SRB, quantified the effect of ecological restoration projects on the ecosystem carbon fixation capacity, and identified sensitive and vulnerable areas of carbon loss against the background of climate and land use/cover change (LUCC). The results show that the ecosystem carbon storage in SRB changed significantly before and after the ecological project implementation, with a decrease of 5.71 Tg in 1986-2000 and an increase of 14.11 Tg in 2000-2016. The proportion of carbon sink enhancement areas was only 7.46% in 1986-2000, which increased to 15.04% in 2000-2016, indicating that the ecological restoration effect of the watershed was obvious as a result of the ecological management. The contribution of LUCC brought about by the ecological restoration project to the increase in ecosystem carbon storage was as high as 103.71%, for which the increase in woodland and grassland was the key. However, in 2000-2016, low carbon optimization areas accounted for 4.17% and carbon emission control areas for 6.16% of the total area of SRB. The carbon fixation capacity of these areas declined, and carbon emissions were elevated, especially in carbon emission control areas. These were mainly distributed in the oasis-desert transition zone in the mid-lower reaches, which are sensitive and vulnerable areas for carbon loss. Therefore, in future ecological restoration and protection processes, these areas should be given more attention and protection.