Quantifying impacts of climate dynamics and land-use changes on water yield service in the agro-pastoral ecotone of northern China

Species distribution modeling combined with environmental DNA analysis to explore distribution of invasive alien mosquitofish (Gambusia affinis) in China

China has become one of the most serious countries suffering from biological invasions in the world. In the context of global climate change, invasive alien species (IAS) are likely to invade a wider area, posing greater ecological and economic threats in China. Western mosquitofish (Gambusia affinis), which is known as one of the 100 most invasive alien species, has distributed widely in southern China and is gradually spreading to the north, causing serious ecological damage and economic losses. However, its distribution in China is still unclear. Hence, there is an urgent need for a more convenient way to detect and monitor the distribution of G. affinis to put forward specific management. Therefore, we detected the distribution of G. affinis in China under current and future climate change by combing Maxent modeling prediction and eDNA verification, which is a more time-saving and reliable method to estimate the distribution of species. The Maxent modeling showed that G. affinis has a broad habitat suitability in China (especially in southern China) and would continue to spread in the future with ongoing climate change. However, eDNA monitoring showed that occurrences can already be detected in regions that Maxent still categorized as unsuitable. Besides temperature, precipitation and human influence were the most important environmental factors affecting the distribution of G. affinis in China. In addition, by environmental DNA analysis, we verified the presence of G. affinis predicted by Maxent in the Qinling Mountains where the presence of G. affinis had not been previously recorded.

The contributions of climate and land use/cover changes to water yield services considering geographic scale

Background

Water yield services are critical for maintaining ecological sustainability and regional economies. Climate change and land use/cover change (LUCC) significantly affect regional water yield, but the spatiotemporal variability of water yield services has been overlooked in previous studies. This study aims to explore the relative contributions of climate and land use/cover changes to water yield services at both grid and subwatershed scales.

Methods

This study employed the InVEST model to calculate the water yield in the study area and employed a multi-scenario simulation approach to investigate the impacts of climate change and LUCC on water yield at both grid and subwatershed scales. Furthermore, the contributions of these two types of changes to water yield were quantified.

Results

Firstly, upstream areas experience significantly lower annual average precipitation, temperature, and potential evapotranspiration than downstream areas, with worsening drought severity. Secondly, urbanization led to significant LUCC, with decreases in farmland and grassland and increases in forest, water, building land, and unused land. Thirdly, the spatial heterogeneity of water yield services remains consistent across different scales, but more pronounced spatial clustering is observed at the subwatershed scale. Fourthly, climate change is the primary factor affecting regional water yield services, surpassing the influence of LUCC. Lastly, LUCC significantly impacts water cycling in watersheds, with vegetation coverage being a critical factor affecting water yield.

Conclusion

These findings highlight the need to consider the complex relationships between climate change, LUCC, and water yield services at multiple scales in water resource management.

Evaluating the impacts of land use change on ecosystem service values under multiple scenarios in the Hunshandake region of China

Changes in land use in an agro-pastoral region affect the delivery of ecosystem services. The trajectory of future land use change and its impacts on human society are not yet well understood, which poses a challenge to efforts to balance the socioeconomic development with the supply of ecosystem services. Taking the Hunshandake region for a case study, we developed four land use scenarios, and projected the future land use patterns under those scenarios using the GeoSOS-FLUS model. We then assessed the ecosystem service values (ESV) using a modification of the equivalent-coefficient method that accounts for differences in net primary production, and explored the impacts of land use change on ESV from 2018 to 2030. We found important land use conversions among the forest, grassland, and cropland uses, mainly in the southern part of our study area. The presence of ESV change hotspots and cold spots suggested that the changes were clustered in the southeastern part. The ESV gain and loss matrix showed that the land use changes under a scenario that prioritized ecosystem services and the comprehensive development scenario increased ESV from 2018 to 2030 with the conversion of cropland to forest. Our results provide important knowledge to inform land use decisions and facilitate sustainable development in the Hunshandake region.

Watershed Ecohydrological Processes in a Changing Environment: Opportunities and Challenges

Basin ecohydrological processes are essential for informing policymaking and social development in response to growing environmental problems. In this paper, we review watershed ecohydrology, focusing on the interaction between watershed ecological and hydrological processes. Climate change and human activities are the most important factors influencing water quantity and quality, and there is a need to integrate watershed socioeconomic activities into the paradigm of watershed ecohydrological process studies. Then, we propose a new framework for integrated watershed management. It includes (1) data collection: building an integrated observation network; (2) theoretical basis: attribution analysis; (3) integrated modeling: medium- and long-term prediction of ecohydrological processes by human–nature interactions; and (4) policy orientation. The paper was a potential solution to overcome challenges in the context of frequent climate extremes and rapid land-use change.

Scenario Analysis of Livestock Carrying Capacity Risk in Farmland from the Perspective of Planting and Breeding Balance in Northeast China

In this paper, we selected the northeast region as a study area from the perspective of soil nutrient demand, calculated the livestock carrying capacity of farmland under three scenarios where nitrogen nutrient accounts for 35% (low level), 45% (medium level), and 55% (high level) of fertilization, and carried out a risk analysis. The results show that the scale of husbandry breeding is expanding and the scale of the planting industry has remained basically unchanged. Under the three scenarios, there were 23 regions where the livestock manure exceeded the maximum value that could be absorbed by farmland in 2008 and 28 regions in 2019. These regions in the potential area are mostly located in Heilongjiang province and the regions in the restricted area are mostly located in Liaoning Province. On the whole, the northeast region is generally faced with the problem of livestock overloading, and the insufficient utilization and treatment capacity of livestock manure poses a huge threat to regional ecological security. Based on this, adjusting the structure of regional planting and breeding, promoting the development of the livestock manure processing industry, enhancing the production capacity of organic fertilizer, and constructing an integrated pattern of regional planting and breeding are effective ways to realize the sustainable utilization of farmland in northeast China.