Trade-Offs and Synergies of Ecosystem Services and Their Driving Factors on the Northern and Southern Slopes of the Nanling Mountains

The Nanling Mountains are an important ecological barrier in China, where important ecosystem services (ESs) such as habitat quality (HQ), carbon storage (CS), soil conservation (SC), and water yield (WY) are impacted by notable topographic and temperature differences between the northern and southern sides. Spearman correlation analysis was employed to identify the correlations between these services, and the driving mechanisms were elucidated through the utilization of regression models and geographic detectors. The findings indicate the following: (1) ESs demonstrated a general upward trend, with the southern slope exhibiting more pronounced increases compared to the northern slope. The mean WY of the southern slope has been shown to exceed that of the northern slope by 17.2%, while in 2020, there was a 35.2% increase in the southern slope compared with its 1990 value. (2) The majority of ESs exhibit synergistic relationships. For instance, the HQ and the CS are associated with stable synergies, as are the HQ and CS in conjunction with SC. Trade-offs primarily occur between HQ and WY services, whereas the interaction between SC and WY services shifts from one of trade-off to synergy. (3) The driving forces behind the northern and southern slopes are found to be significantly different. The former is found to be controlled by GDP and temperature, whilst the latter is influenced by a combination of GDP, temperature, and slope gradient. The impact of human activity exhibits spatial variability.