Patterns and drivers of carbon stock change in ecological restoration regions: A case study of upper Yangtze River Basin, China.

Balancing ecology and human development has been a long and wide concern. The upper Yangtze River Basin (UYRB) of China has implemented large important ecological restoration projects since the last century. These restoration practices have changed land use patterns within the UYRB, consequently impacting the local carbon cycle. The most noteworthy project is the Grain for Green Program, which returns cropland to natural vegetation (forest and grassland). Yet the effects of restoration on land use change, carbon sequestration, and associated food production remain unclear. This study utilized remote sensing data and conversion coefficients to analyze the ecological-policy-induced land use changes of the UYRB from 2000 to 2020 and their impacts on terrestrial carbon sequestration. Linear regression, machine learning, and structural equation modeling (SEM) were utilized to evaluate the correlations between environmental and socio-economic factors and the distribution of carbon stocks. The results indicated positive effects of ecological activities on the UYRB, despite decreases in cropland. Over the past 20 years, the UYRB had sequestered carbon by a total amount of 1796 ± 926 Mt C. The spatial distribution of sequestered carbon demonstrated a strong correlation with slopes, followed by temperatures. The SEM results indicated that agricultural production and carbon sequestration were enhanced synergically under land use changes. This further demonstrated the effectiveness of these land policies in achieving a balance between crop productivity and ecology protection. We emphasized the importance of vegetation restoration in achieving carbon neutrality and the necessity to continue these projects. We suggested a more reasonable land management for the future UYRB based on the characteristics of each geographical subregion. This work serves as an example of effective land management to other locations worldwide perusing the harmony of ecological restoration and human development.

Sectorial water use trends in the urbanizing Pearl River Delta, China.

Assessing and managing water use is crucial for supporting sustainable river basin management and regional development. The first consistent and comprehensive assessment of sectorial water use in the Pearl River Delta (PRD) is presented by analysing homogenized annual water use data from 2000 to 2010 in relation to socio economic statistics for the same period. An abstraction of water use, using the concept of water use intensity, and based on equations inspired by those used in global water resource models, is developed to explore the driving forces underlying water use changes in domestic, industrial and agricultural sectors. We do this at both the level of the region as a whole, as well as for the nine cities that constitute the PRD separately. We find that, despite strong population and economic growth, the PRD managed to stabilize its absolute water use by significant improvements in industrial water use intensities, and early stabilisation of domestic water use intensities. Results reveal large internal differentiation of sectorial water use among the cities in this region, with industrial water use intensity varying from -80 to +95% and domestic water use intensity by +/- 30% compared to the PRD average. In general, per capita water use is highest in the cities that industrialised first. Yet, all cities except Guangzhou are expected to approach a saturation value of per capita water use much below what is suggested in recent global studies. Therefore, existing global assessments probably have overestimated future domestic water use in developing countries. Although scarce and uncertain input data and model limitations lead to a high level of uncertainty, the presented conceptualization of water use is useful in exploring the underlying driving forces of water use trends.

Europe's terrestrial biosphere absorbs 7 to 12% of European anthropogenic CO2 emissions.

Most inverse atmospheric models report considerable uptake of carbon dioxide in Europe's terrestrial biosphere. In contrast, carbon stocks in terrestrial ecosystems increase at a much smaller rate, with carbon gains in forests and grassland soils almost being offset by carbon losses from cropland and peat soils. Accounting for non-carbon dioxide carbon transfers that are not detected by the atmospheric models and for carbon dioxide fluxes bypassing the ecosystem carbon stocks considerably reduces the gap between the small carbon-stock changes and the larger carbon dioxide uptake estimated by atmospheric models. The remaining difference could be because of missing components in the stock-change approach, as well as the large uncertainty in both methods. With the use of the corrected atmosphere- and land-based estimates as a dual constraint, we estimate a net carbon sink between 135 and 205 teragrams per year in Europe's terrestrial biosphere, the equivalent of 7 to 12% of the 1995 anthropogenic carbon emissions.