Hotspots of Yield Loss for Four Crops of the Belt and Road Terrestrial Countries under 1.5 °C Global Warming

The Fifth Assessment Report of the Intergovernmental Panel on Climate change (IPCC) shows that climate change poses severe risks to the Belt and Road region and could cut future crop production. Identifying the positions and features of hotspots, which refer to regions with severe yield loss at 1.5 °C global warming, is the key to developing proper mitigation and adaptation policies to ensure regional food security. This study examined yield loss hotspots of four crops (maize, rice, soybean and wheat) at 1.5 °C global warming under RCP8.5. Yield data were derived from simulations of multiple climate-crop model ensembles from the Inter-Sectoral Impact Model Intercomparison Project (ISI-MIP). Hotspots were identified by setting a threshold of the 10th percentile of crop yields during the reference period (1986–2005). To quantify the likelihood of crop yield loss hotspots within multi-model ensembles, the agreement of model combinations for hotspots was calculated for each crop at the grid scale with 0.5° × 0.5° spatial resolution. Results revealed spatial heterogeneity of cultivation structure and hotspot likelihood for four crops. The four crops’ production of SA (South Asia) and SEA (Southeast Asia) accounts for more than 40% of the total production in the Belt and Road region, roughly four times the amount produced in CEE (Central and Eastern Europe) and NEA (Northeast Asia). Besides, the hotspots likelihood of maize, rice and soybean is generally larger in SA/SEA than that in CEE/NEA which means the risk of yield reduction is higher in the current main agricultural area. According to IPCC’s classification rules for likelihood, four crops’ hotspot patterns were displayed under the 1.5 °C global warming. As the highest-yielding crop, maize shows the largest proportion of “likely” hotspots (hotspot likelihood > 66%), which is about 6.48%, accounting for more than four times that of the other three crops. In addition, four crops’ hotspots are mainly distributed in SEA and SA. Overall, SEA and SA are vulnerable subregions and maize is the vulnerable crop of the Belt and Road region. Our results could provide information on target areas where mitigation or adaptations are needed to reduce the adverse influence of climate change in the agricultural system

Modeling the Relative Contributions of Land Use Change and Harvest to Forest Landscape Change in the Taihe County, China

Forests are under pressure from land use change due to anthropogenic activities. Land use change and harvest are the main disturbances of forest landscape changes. Few studies have focused on the relative contributions of different disturbances. In this study, we used the CA-Markov model, a land-use change model, coupled with a forest landscape model, LANDIS-II, to simulate dynamic change in Taihe County, China, from 2010 to 2050. Scenarios analysis was conducted to quantify the relative contributions of land use change and harvest. Our results show that forestland and arable land will remain the primary land-use types in 2050, whereas the built-up land will sprawl drastically. Land use change and harvest may result in the significant loss of forest area and changes in landscape structure. The simulated forest area will increase by 16.2% under the no disturbance scenario. However, under harvest, forest conversion, and integrated scenario, the area will be reduced by 5.2%, 16.5%, and 34.9%, respectively. The effect of harvest is gradually enhanced. The land use change will account for 60% and harvest will account for 40% of forest landscape change in 2050, respectively. Our results may benefit from the integration of regional forest management and land-use policy-making, and help to achieve a trade-off between economy and ecological environment

Statistical relations between geomorphic parameters - A case study of the Yunnan reach of the Lancangjiang River in southwestern China

The properties of rivers and their catchments can be expressed by statistical relationships between geomorphic parameters. These statistical relationships may reveal some inherent differences in geomorphic evolution for different reaches or different order tributaries of a river basin. A case study was undertaken of the Yunnan reach of the Langcangjiang River. The catchment area, channel length and gradient of the first-, second-and third-order tributaries all with catchment areas larger than 100 km² in the Yunnan reach were the main geomorphic parameters evaluated. The correlation between catchment area and channel length as well as between catchment area and channel gradient with respect to the total tributaries, different reach tributaries, and different order tributaries were revealed using statistical methods. In general, the channel length as a function of catchment area, was best expressed by a quadratic function where channel length increases with increasing catchment area (half parabola), while the channel gradient as a function of catchment area is best expressed by an exponential decay function. Comparison of the best-fit formulas revealed the following phenomena: the lower Yunnan reach tributaries and the first-order tributaries have a dominant effect on geomorphic parameters of the total tributaries. In addition, the statistical relationships indicate that the river geomorphic system in the upper and lower Yunnan reaches evolved differently. This study method used to differentiate river characteristics by determining statistical relationships between geomorphic parameters may be extended to other rivers and their catchments

Quantifying Co-Benefits and Trade-Offs between Forest Ecosystem Services in the Gan River Basin of South China

Forest ecosystem services are intrinsically linked. We design a spatially explicit approach to quantify and analyze the co-benefits and trade-offs between the main forest ecosystem services. Our goal is to develop criteria for forest management that include ecosystem service interactions. Chinese fir and pine plantations provide the largest portion of the overall ecosystem services currently provided. They are volume stock and water yield service hotspots, but these have negative effects on soil retention and carbon storage, causing environmental problems. The natural forests (broad-leaf and bamboo forests) are carbon storage and volume stock hotspots and show the lowest erosion modulus. Thus, their protection, combined with expanding the plantation area under forest management should be considered in order to increase ecosystem service synergies. In contrast, an increased area of broad-leaf plantations reduces water yield service due to their lower water production capacity, in comparison with plantations of fast-growing species. Our study shows that the inclusion of ecosystem services as part of forest management could provide opportunities for optimal allocation of forest resources and sustainable utilization. Management based only on economically beneficial ecosystem services can be detrimental to the forest ecosystem and can cause environmental problems

Effects of Climate Change and Fencing on Forage Nutrition Quality of Alpine Grasslands in the Northern Tibet

How climate change and fencing will affect forage nutrition quality of alpine grasslands is still unknown in the Northern Tibet. Here, we reported the effects of climate change and fencing on forage nutrition quality (i.e., CP: crude protein, ADF: acid detergent fiber, NDF: neutral detergent fiber, Ash: crude ash, EE: ether extract and DTS: dissolvable total sugar) in alpine grasslands across the Northern Tibet based on a transect survey dataset from 2018. Over the whole survey transect, fencing reduced the NDF content by 5.15% and the EE content by 15.79%, but did not affect forage nutrition quality (R2 = 0.04, p = 0.389). Air temperature and precipitation explained 24% and 8% of variation in the CP content under the fencing conditions, respectively. Precipitation explained 22% of variation in the NDF content under the fencing conditions. The CP content decreased and increased exponentially with increasing air temperature under the fencing and grazing conditions, respectively. The NDF content showed logarithmic and negative relationships with precipitation under the fencing and grazing conditions (−8.45 vs. −6.68lnNDF). The response of the CP content to fencing showed negative relationships with temperature and the response of AGB to fencing, but showed a positive relationship with precipitation. The CP and DTS contents showed negative relationships with AGB under the fencing and grazing conditions. In contrast, the ADF content showed a positive relationship with AGB. The response of AGB, SR and community composition to fencing explained 11%, 56% and 35% of variation in the response of forage nutrition quality to fencing, respectively. Therefore, climate change may not always have adverse effects on forage nutrition quality, whereas fencing may not always have favorable effects on forage nutrition quality. Fencing and climate change can have an interactive effect on forage nutrition quality. Fencing can alter the temperature and precipitation sensitivities of forage nutrition quality. In colder and wetter regions, the forage nutrition quality may be more responsive to fencing. There may be a trade-off between forage nutrition quality and quantity. Compared to the change in AGB caused by fencing, the changes in species α-diversity and community composition caused by fencing can have greater effects on the response of forage nutrition quality to fencing. Local climate conditions and the trade-offs between forage nutrition quality and biomass should be considered when evaluating the effects of fencing on the restoration of degraded grassland plants

Effects of Land-Use Intensity and Land Management Policies on Evolution of Regional Land System: A Case Study in the Hengduan Mountain Region

In the last few decades, land use/land cover (LULC) has changed significantly under the influence of local planning and policy implementation, and this has had a profound impact on the regional ecological environment. By taking the Hengduan Mountain region as the study area, this study considered the demands of various commodities and services and applied the CLUMondo model to predict the trajectory of change in the land system for the years 2010–2030. The results indicate that the forest system expands significantly in this time, while the grassland and cropland systems are projected to develop intensively under the three scenarios. The high demand for livestock products is the main cause of the intensification of the grassland system under the TREND scenario, the demand for forests leads to the expansion of the forest land system under the FOREST scenario, and the significant intensification of the cropland system under the CONSERVATION scenario is closely related to an increase in the area of ecological land. The results of this study can provide a scientific reference for the optimal management of land systems in other mountainous areas

Study on the Ecosystem Service Supply–Demand Relationship and Development Strategies in Mountains in Southwest China Based on Different Spatial Scales

Mountainous regions typically exhibit a strained relationship between humans and the land, with noticeable spatial differences in the supply and demand of ecosystem services (ESS and ESD, respectively). ESS and ESD display varying characteristics at different spatial scales. Research on ESS and ESD at multiple scales can aid regional development and efficient ecosystem management. However, the current research focuses on ESS and neglects the ES characteristic changes at different scales. This study concentrates on the Hengduan Mountain region in southwest China. It evaluated ESS and ESD, analyzed the spatial matching relationship, and proposed a corresponding development strategy. The results demonstrated four key findings. First, ESS displayed an inverse spatial distribution on the two scales and was lower in the north and higher in the south at the raster scale. Over the period 2000–2020, ESS exhibited a pattern of initial increase, followed by a decrease, albeit with varying spatial patterns. Changes in land use primarily drove these ESS changes. Second, ESD increased from northwest to southeast on both scales and showed a rising trend over time. Third, at the grid scale, the low supply and low demand (L-L) region is primarily situated in the northwestern part, and it is crucial to prevent grassland degradation and manage grazing intensity. The low supply and high demand (L-H) region is located in the southeast, where the protection of cultivated land, along with comprehensive control of rocky desertification and debris flow, should be prioritized. High supply and low demand (H-L) are found in the northern mountain area, where paying attention to soil erosion control is essential. For areas with high supply and high demand (H-H) types, efforts should be directed toward maintaining forest habitat integrity. Fourth, on the county scale, L-H types should focus on realizing the ecosystem service value and implementing ecological agriculture. H-L counties can appropriately develop economic activities. Simultaneously, ecological compensation should be conducted among counties