Tradeoffs among ecosystem services under ecological engineering construction: Donor and receiver evaluation of 25 soil and water conservation projects in China

China's recent ambitious ecological goals have driven ecological engineering projects, some of which have faced criticism for inefficiency and increasing trade-offs among ecosystem services (ESs). Evaluating these projects is crucial for developing more sustainable solutions. To address this issue, we develop a comprehensive evaluation framework that combines emergy analysis (donor side) and economic analysis (receiver side) to assess the value of five key ecosystem services (ESVs) using 25 soil and water conservation projects (SWCPs) as case studies. Furthermore, we apply partial least squares-structural equation modeling (PLS-SEM) to analyze the interaction mechanisms among drivers, including measures factors (measures), terrain factors (terrain), environmental factors (environment), and climatic factors (climate). The results show that after the SWCPs construction, although increase in the total ESs value (ESV_T) have been found, the decrease of water conservation is demonstrated from both emergy and economic analysis. Carbon sequestration increased in all studied SWCPs expect the Gaocang river small watershed. Inconsistent results from the two adopted methods suggest that the ecological engineering evaluation should consider from both donor side and receiver side. Tradeoffs among ESVs, most notably in soil retention and water conservation pair, suggest the SWCPs are uncoordinated with local ESs. Results derived from our proposed indicators show that the emergy sustainability index (ESI) of more than half of the studied SWCPs decreases, while the cumulative present value of 8 SWCPs also declines. Finally, we find that terrain and climate are the primary drivers of ESVs increases, whereas environment and measures have the most significant negative impacts. Measures weakens the positive effect of terrain while amplifying the negative effect of environment. Finally, suggestions toward optimized ecological construction were raised.