Surplus or deficit? Quantification of carbon sources and sinks and analysis of driving mechanisms of typical oasis urban agglomeration ecosystems

The relationship between carbon sources and sinks, along with their balance, is a crucial indicator for assessing ecosystem health. Ecosystem protection mitigates climate change and promotes the carbon cycle balance. Consequently, to effectively assess the status of carbon sources and sinks in an oasis ecosystem, this study utilized remote sensing and statistical data to estimate the natural carbon sources and sinks, energy carbon emissions(ECE), and carbon surpluses or deficits in the urban agglomeration of the northern slopes of the Tianshan Mountains(UANSTM) for a period 2000-2022 from a perspective of the natural-social-economic system. The driving mechanisms were analyzed using the optimal geodetector model (OPGD) and generalized divisia index method (GDIM). The results show(1) throughout the study period, natural carbon sources and sinks in the UANSTM exhibited a distribution pattern that diminished from the Tianshan Mountains axis northward and southward, accompanied by a fluctuating increase over time. ECE predominantly occurred in urban built-up areas and adjacent cultivated lands, totaling an increase of 88.48 × 10⁴ TgC. (2) The change trend showed an overall predominance of carbon sources, with the rate of increase of carbon sources being greater than that of carbon sinks. Grassland-cultivated land and construction land interaction area exhibited significant changes in carbon sources and sinks. (3) During the study period, the UANSTM experienced a consistent carbon deficit, averaging -68.11 TgC annually. Spatially, this deficit evolved from discrete points to linear and then to areal patterns. (4) Precipitation and elevation were the primary determinants of natural carbon sources and sinks. Whereas GDP with a contribution of 50.4%,was the predominant driver of ECE across each prefecture-level city. Development of policies that synergize regional natural and socioeconomic systems is an important means of achieving a carbon balance. The results of this study provide a reference for adding a research paradigm on carbon sources and sinks in oasis urban agglomerations and for low-carbon development.