Potential distribution area plays important roles for estimating crop planting range and production, evaluating the impact of climate change on agricultural production, planning agricultural structure, and avoiding natural and market risks, among others. The Indo-China Peninsula (ICP) is a dominant region for rice production and plays a vital role for the food security of the world. This study modeled the potential distribution area of rice production across the ICP using MaxEnt—a popular software for species distribution modeling. The results show that: (1) Eight environmental factors, i.e, elevation, slope, irrigation cost distance, isothermality, temperature annual range, annual precipitation, precipitation seasonality and precipitation of warmest quarter, are the main influencing factors for rice production distribution in the region; (2) The model accuracy increased significantly (p<0.05) when all rice samples were divided into three subgroups (lowland irrigation, lowland rainfed, and upland rainfed) before modeling; (3) The potential distribution area of rice production in the ICP is 114 million hectares, which accounts for 53.3% of the total land area of the region. The results of the potential distribution area of rice production can offer scientific supports for guiding rice plantation pattern, safeguarding regional food supply, and optimizing the agricultural industry in the ICP region.
Laos is China’s important neighboring country and one of the key regions of the Belt and Road initiative. It is also the only landlocked country in Southeast Asia. Its economic foundation is weak, but the development momentum is high. The economic and social developments are deeply influenced by the neighboring countries. Accurate understanding of the spatial pattern and temporal changes of Laos’ economic and social developments is of great practical significance for China-Laos cooperation. Based on the long time series nightlight data, this study developed a Defense Meteorological Satellite Program (DMSP) and Visible Infrared Imaging Radiometer Suite (VIIRS) nighttime light data integration method suitable for Laos. Through the analysis of the spatial differentiation of the current situation of nighttime lights in Laos, the temporal and spatial change of light gravity center, the areal change of high value areas of lights in each administrative region, and the temporal and spatial characteristics of lights in major cities and border areas, this study systematically examined the spatial pattern and change characteristics of economic and social developments in Laos in recent 30 years. (1) In 2020, the total area of high value areas of lights in Laos was 2488.9 km2. Vientiane, the capital city of Laos, was still in an absolute dominant position in spite of a continuous decline in city primacy level. In 2020, the high value areas of lights in Vientiane accounted for 1/3 of the total area of that in Laos. (2) The spatial variation trajectory of light center of gravity showed a distinct V shape. After 2006, urban development in the northern region was faster than that in the southern region, and the economic and social development gaps between the north and the south decreased. (3) From 1992 to 2020, the economic and social developments of Laos continued, and the total area of the high value areas of lights increased by 85.4 km2 annually. According to the areal evaluation of the high value areas of lights in 2020, the five largest cities in Laos were Vientiane, Basse, Sawan Naket, Luang Prabang, and Xayaburi. (4) The Laos-Thailand border area is the main area of economic and social activities in the border areas of Laos, with the area of high light value accounting for 35.7% of the country’s total and 90.5% of the border areas. The Laos-China border area, though small, has seen the biggest increase.
Cambodia has abundant arable land resources, suitable temperature, and great potential for rice plantation. Timely acquisition of rice cropping system information is important for regional rice production management, disaster risk assessment, and food policy formulation. Most traditional rice remote sensing monitoring studies only provide spatial patterns of rice distribution at the interannual scale, and information on rice planting and harvesting at the intraannual scale is often lacking. In this study, first all available MODIS time series data in a year were used to construct an image-based MODIS NDVI annual time series curve; the maximum value, minimum value, mean value, and standard deviation were selected to calculate the image-by-image time series statistical parameter features, and the FastDTW algorithm was used to calculate the similarity features between the image-by-image time series curve and the rice reference time series curve, and then the time series statistical features were combined with the time series curve similarity features, and the rice maturation information was extracted by supervised classification through machine learning using a random forest classifier. Finally, the rice phenological features extracted from the time series curves were combined to generate rice harvest time information for the identification of rice cultivation types. The study showed that rice cultivation in Cambodia is mainly concentrated in the lowland plains around the Tonle Sap Lake and the lower Mekong River. Although the thermal conditions in Cambodia are suitable for rice cultivation throughout the year, water access constraints have a significant impact on the spatial and temporal patterns of rice cultivation in the country. The rice maturity mode indicates that production was dominated by single-season rice, which accounted for about 80% of the annual rice cultivation area and had a stable distribution area; double-season rice accounted for about 20% of the area and showed a large interannual variation in the spatial distribution of cultivation. Wet season rice was the main type of rice cultivation in the country, and the planted area accounted for about 70% of the annual rice area with little interannual variation; dry season rice and ex-rainy season rice accounted for about 30% of the area, with significant interannual variation in spatial distribution. The analysis of rice cropping patterns in 2011 and 2016 showed that irrigation conditions and flooding had important spatial and temporal effects on rice cultivation in Cambodia. This study identified the main influencing factors through high-precision monitoring of the interannual and intraannual spatial and temporal patterns of rice cultivation in Cambodia, which provide a reference for the development of a locally adapted and resilient rice cultivation system to ensure food security in the country.
Rubber forests are important economic forest species and strategic materials in Southeast Asia. Timely and accurate detection of the spatial and temporal dynamics of rubber forests is important for the scientific formulation of rubber forest plantation planning, promoting local economic development, and maintaining a healthy and stable ecological environment. For an in-depth exploration of the spatiotemporal dynamics of rubber forests in Mon State, Myanmar, this study selected Landsat long time series remote sensing images from 2000 to 2019 and used the continuous land cover change detection and classification (CCDC) algorithm to obtain each continuous change image pixel through change detection. Then, using the random forest (RF) classification algorithm, the classification results of rubber forests and related land cover types were obtained. At last, on the basis of accuracy verification, an analysis of the spatiotemporal expansion of rubber forests and their encroachment on other land cover types were conducted. The results show that: (1) The spatial and temporal distribution of rubber forests and related land cover types can be extracted accurately by the CCDC algorithm using time series Landsat data, with the overall classification accuracy higher than 85% and an F1 score greater than 80%, and the classification accuracy of rubber forests is higher than 80%. (2) Rubber forests in Mon State was expanding year by year, with the area of rubber forests increasing from 7.25×10 4 hm2 to 19.72×104 hm2 between 2000 and 2019, an increase of 1.72 times. (3) From the perspective of land cover, the expansion of rubber forests was mainly achieved by encroaching on natural forest and cropland. The encroachment area was 12.47×104 hm2 over the past 20 years; among this, the encroachment area of natural forest was the largest, at 10.52×104 hm2, accounting for 84.36% of the total encroached land area. The expansion of rubber forests is affected by social and economic factors such as price. In the past 20 years, the encroachment of rubber forests on both natural forest and cropland showed a trend of first increasing and then decreasing, which is basically consistent with the fluctuation rate of the average annual export price of rubber. These results may provide a decision support for rational rubber production planning and sustainable development of the ecological environment in Mon State, Myanmar.
“Development Triangle” comes into being with the transition from geopolitics to geo-economics since the 1990s. The Cambodia-Laos-Vietnam Development Triangle Area (CLV-DTA) founded in 1999, is the most developed among the several DTAs in Mainland Southeast Asia and has attracted much attention from the Association of Southeast Asian Nations (ASEAN), the Asian Development Bank (ADB), and the World Bank (WB) in their tenth biannual summit in 2018. With the continuous advance of geo-economic cooperation led by Vietnam, the involved provincial units in the CLV-DTA continue to expand from seven at its beginning, ten in 2004 and 13 in 2009, and has also experienced land use/cover changes dominated by agriculture expansion and forest loss. Compared with the traditional geo-economic analysis, the investigation in the interaction between geo-economic cooperation and border land use is obviously inadequate and requires in-depth examination. According to the four key nodes (1999, 2004, 2009 and 2018) with geo-influence in the CLV-DTA, seven years’ SERVIR-Mekong land cover data products launched by the United States Agency for International Development with a five-year interval during 1988-2018, were selected and applied to depict quantitatively the spatiotemporally dynamic characteristics of agricultural expansion and forest loss in this DTA in the past three decades with GIS-based spatial analyses. The results showed that: (1) Forest, cropland and plantation/orchards were the main types of land cover. Land use/cover changes are dominated by the way of agricultural expansion and forest loss. (2) Agricultural expansion and forest loss first strengthened and then gradually weakened, especially before and after the establishment of the CLV-DTA (1998-2003). It showed westward and eastward border-prone trends in Vietnam and Cambodia, respectively, with the Cambodia and Vietnamese border most noteable. (3) The area size of agricultural expansion and forest loss was largest in Vietnamese side of the CLV-DTA, followed by Cambodia and Laos, however, various protected areas in Cambodia suffered the most from agricultural expansion and forest loss and those adjacent to the Cambodia-Vietnam border in particular. (4) Over eighty percent of agricultural expansion and forest loss was occurred and re-occurred in the plains along the Mekong River sand its contiguous hilly area, while it also showed an ascending trend in elevation especially in the low- and medium mountains. As the distance to the available roads (including trails) increases, the quantity of agricultural expansion and forest loss declines steadily within 10 km on both sides, following a distance attenuation pattern, with nearly 70% of the occurrence of agricultural expansion and forest loss within 6 km. This study can provide guidances for exploring the cross interaction between geo-economic cooperation and border land use from research perspective and method.
As a cross-border river that connects six countries, the streamflow changes of the Lancang-Mekong River Basin (LMRB) are closely related to the socioeconomic development and production and life style of the countries in this basin. In order to systematically understand the changes of surface water resources in the LMRB, this study analyzed the trend and abrupt change characteristics of streamflow and quantitatively determined the influence of climate and human activities on streamflow in the basin based on the streamflow and meteorological data from 1961 to 2015. The main conclusions are as follows: (1) At the annual scale, the streamflow of the Jiuzhou Station didn’t show a significant trend from 1961-2010. However, there was a significant decreasing trend at the Yunjinghong Station from 1961-2014. The average streamflow of the Vientiane Station and the Stung Treng Station both showed a trend from decline to rise. At the seasonal scale, the variation trend of streamflow was consistent with that at the annual scale in both the dry and rainy seasons. The variation range of streamflow was small in the dry season but large in the rainy season. (2) The main period of abrupt change occurred in 1998-2000, so the streamflow change period of the four areas (Jiuzhou above, Jiuzhou-Yunjinghong, Yunjinghong-Vientiane, and Vientiane-Stung Treng basins) was divided into before and after 2000. (3) The impact of climate change on streamflow in the LMRB decreased from the upper reaches to the lower reaches (except the delta region) and the impact of human activities increased gradually. The impact of human activities on streamflow in the dry season was greater than that in the rainy season. The variation of streamflow was mainly affected by precipitation in the LMRB while the streamflow at the Stung Treng Station was mainly affected by human activities after 2000.
The natural conditions of agricultural production in the Greater Mekong Subregion (GMS) are superior, but the economic development is relatively backward. Agricultural production plays a very important role in the economic and social development of the region. Based on the panel data of five countries and one province of China in the GMS from 2000 to 2018, this study estimated the regional agricultural production efficiency by using the data envelopment analysis model, and decomposed it into technical efficiency and scale efficiency to reveal the spatiotemporal characteristics of agricultural production efficiency in the region and its influencing factors. The study found that: (1) From 2000 to 2018, agricultural production efficiency in the GMS showed an upward trend, but the level of agricultural production efficiency was relatively low overall. (2) The spatial distribution of agricultural production efficiency is generally high in the periphery and low in the central areas. Laos has been the country with the lowest agricultural production efficiency in the region. (3) Yunnan Province of China, Vietnam, Myanmar, and Thailand have higher comprehensive efficiency of agricultural production, and the improvement of efficiency mainly depends on the pull of agricultural production technology. The contribution of agricultural production technology to the improvement of comprehensive efficiency of agricultural production gradually changed from less than the production scale in the initial stage to greater than the production scale. (4) The spatiotemporal characteristics of agricultural production efficiency in the GMS are the result of the comprehensive influence of natural factors and production factors. Climatic and hydrological factors are the most important factors affecting agricultural production efficiency. With the improvement of agricultural production technology, the effect of landform and topography on agricultural production efficiency is gradually weakened. The increase of the number of agricultural laborers has limited effect on the improvement of agricultural production efficiency. The spatiotemporal patterns of agricultural production efficiency are positively correlated with agricultural land use and agricultural mechanization level. By analyzing the spatial and temporal characteristics and influencing factors of agricultural production efficiency in the GMS, this study not only revealed the agricultural production status in the region, but also provided relevant recommendations for improving agricultural production efficiency in the GMS.
The construction of linear transport corridors has profound impacts on regional landscape patterns. Thus, analyzing the scale effects of corridor construction on landscape patterns, identifying the change trend of landscape affected by railway construction, and achieving a balanced development of linear transport corridor construction and ecological protection are significant for the sustainable development in the region where a railway is located. Taking the China-Laos Railway as an example and based on the land use data between 2015 and 2020, this study applied the land use transfer matrix and regression analysis to analyze the characteristics and spatial differences of the overall and different landscape along the railway and revealed the scale effects of the China-Laos Railway construction on the landscape patterns. The results indicate that: (1) The land use along the China-Laos Railway is mainly forestland. After the completion of the railway construction in 2020, the forest area decreased and cultivated land area increased, and part of the forestland has been transformed into cultivated land. (2) The railway construction led to an increased heterogeneity of the overall landscape pattern, while connectivity among the patches became weakened, patch area decreased, and forest fragmentation increased. (3) The patch density (PD) and dispersion index (SPLIT) of the overall landscape and the forest land are in an inverted U-shaped relationship with the scale effects of the railway. The inflection points of the railway that have a significant impact on the overall and forest landscapes are about 6 km and 8 km respectively from the railway on both sides. The results of this study can be applied to evaluate the impacts of the construction of linear transport corridors such as railways on landscape and guide other countries to formulate more specific landscape protection policies while realizing interconnection between China and other developing countries in the Lancang-Mekong Basin in the future.
Quantifying the effects of burning degree, slope, and vegetation types on the dynamic post-fire vegetation recovery deserves further research for the timely assessment of the rejuvenation and succession of forest-fire burned areas and for promoting the sustainable management of forests. In this study, we selected the Landsat-5/TM, Landsat-7/ETM+, and Landsat-8/OLI time series imagery of two forest-fire burned areas in Yunnan Province (the forest fire in Anning City on 29 March 2006 and the forest fire in Yimen County on 18 March 2012) to assess the burned area recovery. All the images used in this study were collected and the indicators were calculated using the Google Earth Engine (GEE) platform. The normalized burn ratio (NBR) and the differential normalized burn ratio (dNBR) were calculated for extracting the burned areas and classifying the burning degrees, the burned areas were classified into four degrees including low, moderate-low, moderate-high, and high severities according to the dNBR, and we mapped the burned areas and identified the burning degrees for these forest fires. Based on the burn recovery ratio (BRR), we explored the influence of burning degree, slope, and vegetation types (arbor and shrub) on the change of recovery rate of the forest-fire burned areas, and calculated the values of q for burning degree, slope, and vegetation types respectively by using the Geodetector software. The results show that: (1) For the 29 March 2006 Anning and 18 March 2012 Yimen forest-fire burned areas,based on the BRR, the recovery rate of the burned areas with low and moderate-low burning degrees reached 100% and above after 6-7 years, while the recovery rate of the burned areas with moderate-high and high burning degrees reached 100% after 7-9 years. (2) Among the independent explanatory factors of BRR, the strongest is vegetation type. The second strongest influencing factor is burning degree. In another word, post-fire vegetation type has the greatest influence on the recovery rate of burned areas. The lowest impact independent explanatory factor is slope. The results of this study provide a reference for the evaluation of the recovery status of other burned areas, and also help to understand the dynamic vegetation recovery process after the forest fires in the complex terrain of central Yunnan Province.
The Belt and Road initiative provides an important opportunity for China to achieve high-quality development and it is an important driving force to achieve green transformation under the background of the new economic normal. This study took the Belt and Road initiative as a quasi-natural experiment, and used the difference-in-differences (DID) analysisto examine the impact of the Belt and Road initiative on the green transformation of Chinese cities along the route in 2004-2017 and the mechanism of impact. The study found that the implementation of the Belt and Road initiative significantly promoted the level of urban green transformation and development characterized by green total factor productivity, and there were heterogeneities in the level of urban green transformation between different city types and geographic locations. The initiative significantly promoted the green transformation in central cities, non-resource-based cities, megacities, cities located in middle area, and cities less than 200 km away from the central cities. Further analysis revealed that structural driving force and factor driving force played positive roles in the implementation of the Belt and Road initiative, but the effect of innovation driving force was insufficient. There is a threshold characteristic in the exertion of structural driving force and factor driving force, that is, they can promote urban green transformation when the proportion of urban tertiary industry, the number of college students and the amount of foreign direct investment exceed the critical value. Based on aforementioned findings, the government should continue to establish relevant supporting policies and promote the cities along the route to further integrate into the initiative; Cities should strengthen technological innovation, so as to stimulate the positive effect of innovation driving force on urban green transformation; The government should constantly improve urban comprehensive competitiveness, thus realizing the efficient utilization of policy dividends of Belt and Road initiative.
Price tools play an important role in improving dietary structure and reducing water resources pressure. This study built a 2-Step QUAIDS food demand system model based on the micro level book-entry survey data of 1781 households and estimated the effect of price on the food consumption structure of urban residents in China. On this basis, the study simulated the influence of different price schemes on the water demand for food consumption and the dietary structure of residents. The results show that: (1) With the increase of income, the proportion of meat and fruit consumption in household dietary structure is raising and will continue to increase in the future. Without intervention, such a change, on the one hand, will further promote household demand for food consumption related water resources; on the other hand, it will also increase the imbalance of residents’ dietary structure, affecting their health condition. (2) Reasonable price mechanism is feasible to improve the dietary structure of residents and reduce the pressure on water demand caused by food consumption. A 10% increase in the price of meat consumed at home will reduce the expected value of water footprint of residents’ food consumption by 5.3%. At the same time, this measure will improve the unbalanced state of residents’ dietary structure. In the face of the rapid growth of overweight incidence and the increasing pressure on agricultural water resources, using the price mechanism to achieve the goal of improving people’s dietary structure and reducing the pressure on agricultural water resources has important practical significance.
Carbon quota trading is an effective way to reduce carbon emissions through market mechanisms, and the varied impacts of different allowance allocation methods on the operation of the carbon trading market deserve in-depth study. Taking the Chinese carbon trading market as an example, the liquidity ratio indicator, logarithmic rate of return indicator, random walk process, and difference-in-differences model were used to analyze the liquidity, volatility, and effectiveness of the Chinese carbon trading market under various quota allocation conditions.The results show that: (1) The liquidity of the carbon trading market under the historical method is better than the baseline method, and the liquidity of the carbon trading market can also be improved by increasing the proportion of auction in the mixed quota allocation method. (2) The volatility of the carbon trading market under the baseline method, the historical method, and the mixed quota allocation method is small. Increasing the proportion of auction in the mixed quota allocation method will slightly increase the volatility of the carbon trading market. (3) The mixed quota allocation method is more conducive to improving the information effectiveness of the carbon trading markets than any single quota allocation method. (4) The emission reduction effect of the carbon trading market is better under the baseline method. This study revealed the impacts of various allowance allocation methods on the operation of the carbon trading market, which is significant for the development of more scientific carbon quota allocation methods.
Renewable energy technology innovation is an important part of promoting energy transformation and high-quality economic development. Most of the existing studies focus on domestic economic factors to explore the impact of environmental policies on renewable energy technology innovation, while limited attention has been paid to institutions and conducting research from an international perspective. Based on the panel data of 32 countries from 1998 to 2016, this study used multiple regression analysis method. Firstly, it introduced policy stringency to measure the strictness of policies, exploring the dynamic impacts of domestic and foreign environmental policies on renewable energy technology innovation. Secondly, it used institutional quality as the measurement index of institutional environment, discussing the moderating effect of institutional factors on the effect of environmental policies. The results show that: (1) Domestic and foreign environmental policies both have positive impacts on domestic renewable energy technology innovation, but these effects have a certain time lag; (2) The impact of foreign environmental policies on domestic renewable energy technology innovation is earlier than that of domestic environmental policies, which indicates the existence of “policy spillover” from foreign environmental policies; (3) Institutional quality has a positive moderating effect on the effect of domestic environmental policies. The improvement of institutional quality can enhance the innovation incentive effect of environmental policies. These conclusions provide a scientific basis for the state to further optimize the environmental policy system and promote the development of renewable energy.
The issues of water, energy, and food in the Yellow River Basin are particularly prominent. Research on the coordinated development of water-energy-food (WEF) coupling is helpful for promoting ecological protection and high-quality development in the basin. This study first analyzed the mechanism of WEF coupling and coordinated development in the Yellow River Basin, then constructed the corresponding evaluation indicator system of coupling and coordinated development. Based on that, the coupling and coordination degree model was used to calculate the coupling and coordinated development status of WEF in the basin during 2008-2018 and analyze the characteristics of its temporal and spatial changes. Finally, the grey prediction GM (1, 1) model was used to simulate the coupling and coordinated development of the Yellow River Basin. The results show that: (1) Generally, the WEF systems of the Yellow River Basin were in a stable high-level coupling state in the study period, changing from primary coordination to intermediate coordination in 2010, and from intermediate coordination to good coordination in 2018. (2) The development level of coupling and coordination is quite different spatially. Ningxia is barely coordinated. Henan, Shaanxi, and Gansu Provinces are in the primary coordination category. Shanxi, Inner Mongolia, Shandong, and Qinghai are in the intermediate coordination category. (3) From 2019 to 2023, except for Shaanxi Province, other provinces and autonomous regions are expected to show a slow upward trend. This article also put forward corresponding policy recommendations according to the coupling and coordination characteristics of WEF in various provinces and autonomous regions of the Yellow River Basin.
Hebei Province is one of the most important granaries in China. The long-term over exploitation of groundwater has caused serious ecological and environmental problems. Based on 620 questionnaire survey data of the groundwater irrigation area in Hebei Province in 2019, current water price was calculated by the method of “converting electricity to water”. The fixed water price based on irrigation quota was determined. Nonparametric test was used to estimate the trend relationship between water price and water use. The double logarithm linear model was established to obtain the price elasticity coefficient of irrigation water demand. The threshold estimation method was used to calculate the inflection point of current water price to irrigation water consumption. The results show that: (1) The current irrigation water price is low, which is at 0.35 yuan/m 3, and the current irrigation water consumption is 61.06 m3/mu higher than the irrigation quota, indicating that there is a scope for improvement in water price; (2) The threshold value of water price corresponding to the inflection point of irrigation water demand price curve is 0.33 yuan/m3. The elasticity coefficient below the inflection point is -0.21, and the elasticity coefficient above the inflection point is -0.69, indicating that the increase of water price in the first stage has a weak effect on water saving, and the incentive effect of water price in the second stage on irrigation water saving is significant; (3) The fixed water price of wheat planting is 0.67 yuan/m3. When the water price is raised to the fixed water price, the incentive effect of water price on irrigation water saving is significant. Compared with the current situation, the water saving rate of wheat planting is 27.60%. This study suggested that quota management of irrigation water resources should be adopted for different regions and cropsin order to give full play to the leveraging effect of water prices on agricultural water saving. The study provides a reference for the comprehensive reform of agricultural water pricing in groundwater irrigation area.