Exploring cost-effective measure portfolios for ecosystem services optimization under large-scale vegetation...

Ecosystem services-based land management incorporates environmental features and social needs, providing an important opportunity to realize global sustainability goals. Recent decades, the interaction among water-related ecosystem services (ESs) is getting ambiguous during regional vegetation restoration, which entails challenges for coordinating restoration actions, economic resources, and water-soil resources' availability. In this study, we first explored mechanism of trade-offs among five water-related ESs in the Chinese Loess Plateau under vegetation restoration. Given the decreased baseflow and its widespread trade-offs with water quality, we then developed four scenarios aiming at enhancing the baseflow and nutrient retention in a cost-effective way, by engaging a spatially explicit biophysical software tool-the RIOS model. Moreover, we selected four typical watersheds in the Loess Plateau as cases to demonstrate the differentiated information on the budget levels and the activity sites. The results indicated that, a deep mechanism of scale effects of trade-off among ESs was largely related to spatial heterogeneity rather than spatial resolution, which also affected activity portfolios under different ES scenarios. For the entire Loess Plateau, activity of forest maintenance should be concentrated on the cost-effective locations of investment for the enhancement of baseflow and nutrient retention. Under the regular budget scenarios, trade-offs only could be locally alleviated in reality, while dropping the high-cost ES objectives is an advisable strategy for minimizing investment risk. Taking conservation agricultural practices in the plain river basins should be regarded as a priority when budget can be increased. In contrast, an approach of 'governing by non-interference' for typical watersheds of re-vegetation was sensible strategy for avoiding trade-offs aggravation. These findings emphasized interrelation between the mechanism of ESs trade-offs and activity portfolios, which is an important basis for the implementation of conservation activities in real world context, and a rational reference for the simulation of desired ES goals in future studies.