Since the beginning of the 21st century, the net primary productivity (NPP) of grassland in the Three-Rivers Headwaters (TRH) region has changed significantly. In this study, NPP was assessed by the Carnegie-Ames-Stanford approach (CASA) model in TRH from 2000 to 2019. The abrupt changes of NPP and meteorological factors were analyzed by cumulative departure, MK test, and Pettitt test. The contributions of meteorological and human factors to changes in grassland NPP were quantitatively assessed using the scenario simulation method. The obtained results showed that: (1) From 2000 to 2019, the NPP of grasslands increased from 135.72 to 141.16 gC/m⁻²a⁻¹. However, the overall growth trend was not significant, and the proportion of significant growth was only 31.45%; (2) An abrupt increase in meteorological factors occurred around 2005, while an abrupt increase in NPP occurred around 2008, which showed that 2008 was the year when human factors, such as ecological projects and policies, began to show a significant impact on the growth of NPP; and (3) The contribution of human factors to the abrupt increase in NPP was significantly greater than the contribution of meteorological factors. The contribution of human factors exceeded 70% in 93.68% of the studied area, reaching 98% in general, while the contribution of meteorological factors was less than 2%. Among them, the human contributions to the Yangtze River Source, the Yellow River Source, and the Lancang River Source all exceeded 95%. The negative effects of meteorological factors on the growth of NPP in the abovementioned three regions were as high as 47.35%, 48.66%, and 36.91%, respectively. Human factors have contributed greatly to the increase in NPP in most of the source areas of the Yellow River, the eastern part of Tanggulashan County, the southeastern part of Zhiduo County, and the western part of Zaduo County at the source of the Yangtze River.

Gross ecosystem product (GEP) is the gross value of all ecosystem products and services provided by ecosystems for human society. In practice, GEP measures the ecosystems' contributions to human well-being and constitutes one of the core issues in the construction of ecological civilization systems. Currently, GEP accounting faces a series of problems, such as the inconsistency of accounting subjects and a lack of accounting standards, the result of which is the non-reproducibility and weak applicability of accounting results. In this paper, mainstream models for ecosystem service valuation are summarized in a systematic manner. On this basis, eight basic principles are established for screening accounting indicators: biological productivity, human benefits, production territoriality, current increment, actual effectiveness, physical metrizability, data availability, and harmlessness. Next, a series of ecosystem service subjects are identified that need to be excluded from accounting, and the detailed reasons for their exclusion are presented. Finally, three ideas for improving GEP accounting are offered from the perspectives of the relationship between biological production and human production, the circulation-transport relationship and spatial differences, and harms to the ecosystem carrying capacity. The purpose is to provide positive considerations aimed at promoting the socio-economic applications of accounting and to contribute to the scientific quantification of the values of ecological products.

Harmonizing human activities with the natural environment has received much attention as a development goal and is a longstanding pursuit of human society. In this study, we investigated the sustainability of green development from the perspective of the coordination between economic and environmental subsystems at the place-based scale, with 290 cities in China as research objects. An interdisciplinary method combining an improved data envelopment analysis model and Lotka-Volterra model was conducted to examine the two subsystems’ development efficiency and their correlation (i.e., mutualism, commensalism, amensalism, sacrifice, competition, independence). The results indicate that one-third of the cities’ economic and environmental subsystems are in a mutualistic state, with a relatively stable social-ecological system. However, the two subsystems are in a state of competition in one-fourth of the cities, with rather intense vulnerability, where the harmonious coexistence of humans and nature is facing more significant challenges. In addition, vulnerability of the social-ecological system in economically developed cities shows substantial polarization. The two subsystems in most of these cities are in mutualism or amensalism relations, whereas the social-ecological system in economically underdeveloped cities shows even greater vulnerability.

The implementation of green development has become an important choice for countries seeking the harmonious development of the economy and the environment. The National Ecological Civilization Pilot Zone is an innovative institutional mechanism for exploring green development in China. This study utilizes the National Ecological Civilization Pilot Zone policy as a quasi-natural experiment. Adopting data from 290 prefecture-level and above cities in China during 2014–2019 as the research object, this study matches the propensity score and improved differences-in-differences to assess the impact of green development mechanism innovation on regional total-factor environmental efficiency. The results show that this innovation had a significant impact on the improvement of total-factor environmental efficiency. Compared with non-pilot cities, the implementation of pilot zone areas contributed 16.78% to the growth of total-factor environmental efficiency in the experimental group cities. In addition, further analysis shows that mechanism innovation is more effective in areas with high pollution and high resource consumption. This study enriches the research on evaluation of the impact of innovation in green development mechanisms and provides a reference for further promoting pilot national ecological civilization zones.