The concept of ecosystem services (ESs) is widely recognized for its contribution to human well-being, but ecosystem disservices (EDSs)—the negative impacts of ecosystems—are often overlooked. The Water-Energy-Food (WEF) nexus provides a valuable framework for assessing agricultural sustainability. However, previous studies have primarily focused on ESs while neglecting EDSs and the critical role of water quality. Consequently, the interactions between regulating ESs and EDSs, as well as the connections between water-related and energy-related EDSs, remain insufficiently understood. To bridge this gap, this study aims to assess both ESs and EDSs from the perspective of the WEF nexus. We conducted a case study in Chiayi, Taiwan, a region crucial for crop production yet facing challenges such as greenhouse gas emissions, non-point source pollution, and soil erosion. We used land use maps, the InVEST tool, and local investigations to quantify ESs, including crop provisioning, water yield, nutrient retention, carbon storage, and soil retention, as well as EDSs such as nutrient export, greenhouse gas emissions, and soil erosion. By mapping the provision of ESs and EDSs, we examined their spatial characteristics, synergies, and trade-offs at the county level.
Our results showed median values per hectare for ESs: crop provisioning ($892.00), water yield (16,023.34 m³), nutrient retention (39.60 kg of nitrogen), carbon storage (626.91 mtCO2e), and soil retention (6,048.08 metric tons). For EDSs, the medians were nutrient export (11.41 kg), greenhouse gas emissions (5.97 mtCO2e), and soil erosion (1.13 metric tons). We found that croplands in the plains provided substantial crop provisioning and nutrient retention services but also contributed to greenhouse gas emissions from fertilizer use. In contrast, mountainous areas with forests and orchards offered significant regulating ESs but faced challenges such as high nutrient export and soil erosion. The correlation analysis revealed that crop provisioning and nutrient retention were negatively correlated with all three EDSs. Overall, this study highlights the importance of incorporating EDSs and water quality considerations into the WEF nexus framework. We recommend enforcing agricultural land use regulations and adopting conservation tillage practices to reduce nutrient export and soil erosion in sloped areas, while also improving fertilization practices to mitigate greenhouse gas emissions in agricultural plains.