Identifying driving mechanisms and threshold effects of trade-offs and synergies among ecosystem services: A case study of Henan Province, China

Ecosystem services (ESs) exhibit complex interactions with multiple driving factors, including human activities, climate change, land use, soil erosion, and slope. Henan Province faces ecological challenges such as water scarcity, soil erosion, and biodiversity degradation. Using Henan Province as a case study, this research integrates multi-source data and various models to quantify ESs, identify interrelationships among them, investigate the driving factors influencing these relationships, and determine thresholds for key driving factors from 2000 to 2020. The findings indicate that: (1) ESs in Henan Province showed both trade-offs and synergies. (2) Except for 2010, the key factors of ESs trade-off relationships were only slope, land use; the key factors for the synergies and trade-offs in 2000 and 2020, and the synergies in 2010, were all slope, precipitation (pre), land use, and rainfall erosion (R). Slope, pre, land use, and R maintained strong correlations with ESs synergies and trade-offs throughout the three periods. (3) Land use types showed different correlations with the trade-offs and synergies of ESs pairs, while unused land had no significant correlation. R exhibited two discontinuous sensitive intervals or a single threshold over the three years; slope and pre showed specific sensitive intervals only in 2010 and 2020. Within these thresholds or intervals, the direction of correlation between each factor and ESs pairs reversed.