Reduction Of Cultivated Land Research Articles

The evolution of spatial and temporal distribution of rainfall erosivity in Henan Province, central China

With the advancement of urbanization, there has been a significant reduction in cultivated land, accompanied by soil erosion. Concurrently, the regularity of rainfall in recent years has been erratic, adversely impacting the grain economy and agricultural development in certain regions. Henan Province, spanning the basins of the Yangtze River, the Yellow River, the Huaihe River, and the Haihe River, possesses complex hydrological conditions and serves as a pivotal agricultural zone in China. Therefore, this paper utilizes daily rainfall data collected over 54 years (1969–2022) from 112 rain measuring stations in Henan Province to calculate the rainfall erosivity using the Zhang model and the erosivity model from the first national water survey. Meanwhile, spatial analysis was performed using the Kriging interpolation method in the ArcGIS Geostatistical Wizard, resulting in detailed spatial distribution maps of rainfall and rainfall erosivity. The study also employed Wavelet and Mann–Kendall tests to analyze the abrupt changes, trends and periodicity of rainfall and rainfall erosivity within the target region. The findings indicate that the average rainfall (1969–2022) in Henan province was 718.26 mm, while the average rainfall erosivity (R) was 3213.46 MJ mm/(hm2 h). R values are positively correlated with rainfall intensity and volume, displaying an annual upward trend. Spatially, R values increase gradually from northwest to southeast, closely aligning with topographical variations. Additionally, the analysis revealed a predominant periodic cycle of 54 years in the precipitation patterns. These results offer valuable insights for environmental and agricultural management in other regions of central China.

The Gains and Losses of Cultivated Land Requisition–Compensation Balance: Analysis of the Spatiotemporal Trade-Offs and Synergies in Ecosystem Services Using Hubei Province as a Case Study

The cultivated land requisition–compensation balance (CLRCB) policy is an important policy implemented by China to address the reduction in cultivated land and ensure food security. Although this policy has alleviated the loss of cultivated land quantity, it has had complex and diverse impacts on ecosystem services. Taking Hubei Province as the study area, this research explores the impact of the implementation of the CLRCB on ecosystem services and simulates the changes in ecosystem services in the study area in 2030 and the impact of CLRCB on the interactions among various services. The results show the following: (1) from 2000 to 2020, Hubei Province achieved a balance in the quantity of cultivated land through excessive compensation but failed to reach the goals of balancing cultivated land yield and productivity. (2) During the requisition–compensation process, habitat quality decreased by 501,862, and carbon storage lost 1.3 × 107 t, indicating negative ecological impacts; soil conservation services increased by 184.2 × 106 t, and water production increased by 21.29.3 × 108 m3. Within the cultivated land requisition–compensation area, habitat quality and carbon storage, as well as soil conservation and water production, exhibited synergistic relationships, while the remaining pairs of ecosystem services showed trade-off relationships. (3) The simulation of ecosystem services in 2030 indicates that soil conservation and water production are highest under the natural development scenario, while habitat quality and carbon storage are highest under the ecological protection scenario, both of which are superior to the urban development scenario. Under the natural development scenario, the trade-off and synergistic relationships among various ecosystem services in the cultivated land requisition–compensation area remain unchanged, while these relationships change significantly under the other two scenarios. This study emphasizes that future CLRCB should not only focus on maintaining the quantity of cultivated land but also consider the comprehensive benefits of ecosystem services, in order to achieve sustainable land-use management and ecological conservation.

Spatiotemporal Dynamics and Influencing Factors of Vegetation Net Primary Productivity in the Yangtze River Delta Region, China

Vegetation Net Primary Productivity (NPP) plays a crucial role in terrestrial carbon sinks and the global carbon cycle. Investigating the spatiotemporal dynamics and influencing factors in the Yangtze River Delta (YRD) region can furnish a solid scientific foundation for green, low-carbon, and sustainable development in China, as well as a reference for other rapidly urbanizing regions. This study focuses on the YRD region as an illustration and utilizes the Carnegie–Ames–Stanford Approach (CASA model) to quantify NPP in this region from 2000 to 2018. Investigation into the spatiotemporal dynamics and influencing factors was conducted using Theil–Sen median trend analysis and scenario analysis. The results indicate that the NPP in the YRD region from 2000 to 2018 exhibited pronounced spatial differentiation characteristics, typically exhibiting a spatial distribution pattern of being high in the south and low in the north, high in the west and low in the east. Additionally, the expansion of built-up areas and the reduction in cultivated land have the potential to reduce NPP in the YRD region. Moreover, the influence of land-use and land-cover change (LULCC) is anticipated to be relatively limited compared to that of climate change. Furthermore, changes in precipitation were found to be positively correlated with changes in NPP, with the effect being relatively more pronounced. The correlation between temperature and NPP demonstrated spatial differentiation, with a mainly positive correlation in the central and southern parts of the YRD and a mainly negative correlation in the northern part. Changes in solar radiation had a negative correlation with changes in NPP. Based on these results, it is recommended that local governments strictly enforce urban development boundaries and manage the disorderly expansion of built-up areas, enhance the regional irrigation infrastructure, and address air pollution, so as to ensure the necessary conditions for the growth of vegetation, reduce greenhouse gas emissions, and control regional temperature rises. This study can provide stronger evidence for revealing the influencing mechanisms of NPP through the control of impact conditions and the exclusion of confounding factors via scenario analysis. The policy implications can offer insights into NPP enhancement and environmental management for the YRD and other rapidly urbanizing regions.

Ecosystem Services Response to the Grain-for-Green Program and Urban Development in a Typical Karstland of Southwest China over a 20-Year Period

Southwest China is an ecologically fragile area with a high proportion of karstland and large variations in terrain, and it can be greatly affected by land use change. From 2000 to 2020, with the acceleration of urbanization in the whole country, the macro-scale Grain-for-Green Program (GFGP) has been developed in the karstland of southwest China. This has resulted in the expansion of forest and construction land with a reduction in cultivated land. The response of ecosystem services (ESs) to these changes needs to be investigated. However, there is a lack of in-depth analysis of the karstland of southwest China, and current studies mostly focus on the spatio-temporal variation in individual ESs or how the whole land use change affects ESs. Thus, our study uses an InVEST model and geographically and temporally weighted regression (GTWR) to examine the spatio-temporal variation in land use associated with four ESs, namely water conservancy (WC), soil conservancy (SC), carbon sequestration (CS), and habitat quality (HQ). We found that the GFGP area first increased and then decreased, aggregating to 4.48 × 104 km2 from 2000 to 2020. We also observed that from 2000 to 2020, ESs remained stable or gradually increased (despite fluctuations), SC was the most stable, whereas WC, CS, and HQ first decreased and then fluctuated more. This may be related to the destruction of topsoil in the early stages of the GFGP and the relatively weak ES supply capacity of the young trees. Moreover, the response of ecosystem services to the GFGP was spatially heterogeneous, suggesting a strong driving influence of the local environment, mainly caused by the distribution of karstland and terrain, differentiated urbanization levels, and the intensity of the GFGP. Specifically, the relatively significantly positive effects of WC, SC, and CS were found in western and northern cities, and so was the HQ in southeastern cities. On the contrary, the negative impacts of urbanization were found to weaken over time, suggesting the trade-off effect of the GFGP. Our findings would contribute to the development of effective forest management strategies and provide valuable insights for policymakers and stakeholders involved in ecosystem restoration and conservation efforts by exploring the impacts of the GFGP and urbanization on ESs.

An Alternative Method of Cultivated Land Identification and Its Actual Change from 2009 to 2019: A Case Study of Gaochun, China

As the largest developing country, China has permanently attached great importance to cultivated land protection. However, due to the different rules of cultivated land identification in the second and third national land surveys, the cultivated land area in the two surveys has changed greatly. Some agricultural lands in the south, such as plantations, forests, grasslands, aquaculture ponds, etc., belonged to cultivated land during the second survey, but they were identified as non-cultivated land in the third national land survey. This change has led to a sharp reduction in the area of cultivated land in some places. In order to calculate the actual change in the area of cultivated land since the second survey and provide a reasonable basis for the standard of cultivated land protection, this paper takes Gaochun District, a developed area in China, as an example; interprets the images of the second national land survey period with the deep learning network HRNet; and compares the results with the second and third national land survey rules. The results show that the actual reduction of cultivated land in Gaochun District in the past ten years accounts for 35.1% of the reduction of cultivated land in the two land surveys, while the reduction of cultivated land caused by the change of cultivated land identification rules accounts for 64.9% of the reduction of cultivated land in the two land surveys, indicating that the significant reduction in local cultivated land was mainly caused by the changes in the rules, and these cultivated land reduction behaviors existed before the second survey.

Runoff effect of precipitation variation and landscape pattern evolution in Lianshui watershed, Jiangxi, China.

Precipitation and landscape pattern are two main factors affecting runoff process of the watershed. Understanding their runoff effect is of great significance to water resources management and ecological construction of watershed. Based on the data of precipitation, runoff, and land use from 1958 to 2020, we analyzed the characteristics of precipitation, landscape pattern and runoff in Lianshui watershed in red soil hilly area of southern Jiangxi Pro-vince, established the relationship between precipitation, landscape pattern and annual runoff, flood runoff, low runoff, respectively. The results showed that the annual precipitation, runoff and annual maximum one-day runoff in the watershed showed a non-significant downward trend during the study period, while the annual minimum one-day runoff showed a non-significant upward trend but with the largest inter-annual variation range. Forested land was the landscape type with the highest proportion in watershed, and other woodland had the most dramatic variation. At the landscape level, Shannon diversity index, Shannon evenness index, patch density and landscape shape index increased from 1.125, 0.541, 0.667 and 16.925 in 1980 to 1.348, 0.614, 0.731 and 18.172 in 2020, respectively, while the landscape contagion index decreased from 68.237 in 1980 to 64.293 in 2020. The overall landscape diversity, fragmentation degree and shape complexity of the watershed increased, the spatial distribution tended to be uniform, and the connectivity decreased. The correlation coefficients between precipitation and annual runoff, flood runoff, low runoff were 0.907, 0.594 and 0.558, respectively. At the class level, the reduction of cultivated land had a greater impact on annual runoff, flood runoff, and low runoff, while the overall change at the landscape level promoted a decrease in annual runoff and flood runoff and an increase in low runoff. The contribution rate of precipitation variation and landscape pattern evolution to the change of annual runoff, flood runoff ,and low runoff were 17.8%, 82.2% and 1.5%, 98.5% and -8.8%, 108.8%, respectively. Our results could provide theoretical refe-rence for landscape pattern allocation and comprehensive management of soil and water loss.

Sediment settlement rate and consolidation time of filling reclamation in coal mining subsidence land

With the continuous growth of the population and the continuous reduction of cultivated land, China’s food security is greatly threatened. In addition, China’s coal mining has been mainly underground mining, causing land subsidence and damaging existing cultivated land. This effect intensifies the contradiction between the growth of the risk population and the reduction of cultivated land. The reclamation of mining subsidence land with Yellow River sediment is often used as an effective way to improve the recovery rate of cultivated land. Shortening the reclamation time and realizing continuous filling are significant issues. The work presented in this paper studied the sediment settlement rate and consolidation time by combining theory, field filling and reclamation tests and numerical simulations. A field filling test study was carried out in the lowlands of Jibeiwang Village, Qihe County, Shandong Province, China. By calculating the drainage consolidation time, the consolidation factor of 0.015656 m2/d, and the time factor for sediment consolidation of 0.575 were determined. The sediment consolidation time for this test was 9.18 days. The calculation of sediment deposition rate and consolidation time is of great practical significance to guide the Yellow River sediment filling, realize continuous filling, and save reclamation time and cost.

Influence of coal mining on the lower Yellow River region and related management countermeasures-- Taking Heze mining area as an example

To realize the ecological protection and high-quality development of the Yellow River basin is related to the centenary project of the Chinese nation. The middle and lower reaches of the Yellow River are rich in coal resources and have a long history of mining. Large-scale coal mining activities lead to the destruction of underground aquifer, surface subsidence and the reduction of cultivated land, which seriously threatens the safety of local ecological environment, land resources and water resources. Luxi coal base Heze mining area, for example, the analysis of coal mining activities and land resources, ecological environment, the contradiction between water resources protection and its causes, and put forward preventive measures, to help alleviate the lower Yellow River coal mining and land resources, ecological environment, water resources protection, to realize luxi mining area and the lower Yellow River ecological environment protection and high quality development is of great significance.

Monitoring the Spatio-Temporal Changes of Non-Cultivated Land via Long-Time Series Remote Sensing Images in Xinghua

The amount of cultivated land per capita in China is relatively low, and the phenomenon of non-agricultural cultivated land (NACL) in recent years has negatively impacted the stability of grain production in China. In this study, long-time series images obtained via satellite remote sensing were used to monitor spatio-temporal changes in NACL at the county scale. Seven-phase images were acquired from 1990 to 2020 (every five years) using medium-resolution Landsat MSS, TM, ETM+, and Sentinel MSI. Vegetation indices and texture features were extracted for all images. Terrain features such as slope, aspect and elevation were extracted from the DEM data. Combining vegetation index features, texture features, terrain features and multispectral bands, the image classification was performed using the random forest (RF) algorithm. The indices of classification accuracy assessment indices included overall accuracy (OA) and multiclass F-scores (F_m). Zonal statistics were used to calculate the area of cultivated land in towns for 1990 and 2020, and to create grades for the reduction of cultivated land. Finally, indicators including land use dynamic degree (LUDD), land use type change (LUTC) and land use change rate (LUCR) were adopted to reflect the spatio-temporal of NACL in the study area. The results show that RF classification algorithm achieves accurate and efficient land use extraction. The OA were greater than 86%, and the F_m were over 0.88. The cultivated land area in the study area showed decreasing trend. From 1990 to 2020, the ratio of cultivated land decreased from 59.75% to 50.21%. Meanwhile, the dynamic degree of cultivated land increased annually. The conversion of cultivated land into construction land was dominant, accounting for 31.84% of the total change in cultivated land over the past 30 years. This study also reveals that NACL is highly related to local economic and land-use policies. Multi-source remote sensing data have been used to quantitatively analyse the spatio-temporal changes in cultivated land conversion, providing a reference for relevant land management departments to master cultivated land use changes and adjust land management policies.

Impacts of Agricultural Areas on Spatio-Temporal Variability of Daily Minimum Extreme Flows during the Transitional Seasons (Spring and Fall) in Southern Quebec

Several statistical methods were used to analyze the spatio-temporal variability of daily minimum extreme flows (DMEF) in 17 watersheds—divided into three homogenous hydroclimatic regions of southern Quebec—during the transitional seasons (spring and fall), during the 1930–2019 period. Regarding spatial variability, there was a clear difference between the south and north shores of the St. Lawrence River, south of 47° N. DMEF were lower in the more agricultural watersheds on the south shore during transitional seasons compared to those on the north shore. A correlation analysis showed that this difference in flows was mainly due to more agricultural areas ((larger area (>20%) on the south than on the north shore (<5%)). An analysis of the long-term trend of these flows showed that the DMEF of south-shore rivers have increased significantly since the 1960s, during the fall (October to December), due to an increase in rainfall and a reduction in cultivated land, which increased the infiltration in the region. Although there was little difference between the two shores in the spring (April to June), we observed a decrease in minimum extreme flows in half (50%) of the south-shore rivers located north of 47° N.

Genome-Wide Identification of CBL-CIPK Gene Family in Honeysuckle (Lonicera japonica Thunb.) and Their Regulated Expression Under Salt Stress.

In plants, calcineurin B-like proteins (CBLs) are a unique group of Ca2+ sensors that decode Ca2+ signals by activating a family of plant-specific protein kinases known as CBL-interacting protein kinases (CIPKs). CBL-CIPK gene families and their interacting complexes are involved in regulating plant responses to various environmental stimuli. To gain insight into the functional divergence of CBL-CIPK genes in honeysuckle, a total of six LjCBL and 17 LjCIPK genes were identified. The phylogenetic analysis along with the gene structure analysis divided both CBL and CBL-interacting protein kinase genes into four subgroups and validated by the distribution of conserved protein motifs. The 3-D structure prediction of proteins shown that most LjCBLs shared the same Protein Data Bank hit 1uhnA and most LjCIPKs shared the 6c9Da. Analysis of cis-acting elements and gene ontology implied that both LjCBL and LjCIPK genes could be involved in hormone signal responsiveness and stress adaptation. Protein-protein interaction prediction suggested that LjCBL4 is hypothesized to interact with LjCIPK7/9/15/16 and SOS1/NHX1. Gene expression analysis in response to salinity stress revealed that LjCBL2/4, LjCIPK1/15/17 under all treatments gradually increased over time until peak expression at 72 h. These results demonstrated the conservation of salt overly sensitive pathway genes in honeysuckle and a model of Ca2+-LjCBL4/LjSOS3-LjCIPK16/LjSOS2 module-mediated salt stress signaling in honeysuckle is proposed. This study provides insight into the characteristics of the CBL-CIPK gene families involved in honeysuckle salt stress responses, which could serve as a foundation for gene transformation technology, to obtain highly salt-tolerant medicinal plants in the context of the global reduction of cultivated land.

Study on Water Distribution of Spraying Drone by different Speed and Altitude

The application of unmanned aerial vehicles (UAV) in Malaysia, or best known as a drone, is changing from time to time. Today, drones are used not only in the military, but also in agriculture. The use of drones became common in agriculture due to a reduction in cultivated land, labour shortages and obsolete methods. The spraying of pesticides and herbicides may also be carried out using drones. Furthermore, the time-consumed using drone is faster compared to the conventional method. On the market, there are different kinds and types of drone sprayers. Although the manufacturer has set the Standard Operating Procedure (SOP) for drone usage, the efficacy of spraying should first be examined because of Malaysia's weather and environmental factors which vary from other countries. The purpose of this paper is to investigate the effects of altitude and speed of the drone onto the coverage area during spraying application. In this study, a plot consisting of 0.5 Hectares situated at MARDI Seberang Perai was used. Three different speeds of 2 m/s, 3 m/s, and 4 m/s and three altitudes measured in heights of 1.5 m, 2.0 m, and 2.5 m from the top of the crop were tested. Wind speed and direction were recorded using an anemometer during the study. Water-sensitive paper was used during the experiment to examine the effect on spraying. In order to calculate the coverage area percentage, the spraying effect on water sensitive paper was analysed using ImageJ software. The results are expected to show which speed and altitude may contribute to the largest area of coverage percentage. The appropriate altitude and speed for the spraying operation on the basis of crop requirements can be concluded from the result which is 2 m from above crop at speed of 2.5 m/s.

Land-Use/-Cover Changes and Their Effect on Soil Erosion and River Suspended Sediment Load in Different Landscape Zones of European Russia during 1970–2017

Contemporary trends in cultivated land and their influence on soil/gully erosion and river suspended sediment load were analyzed by various landscape zones within the most populated and agriculturally developed part of European Russia, covering 2,222,390 km2. Based on official statistics from the Russian Federation and the former Soviet Union, this study showed that after the collapse of the Soviet Union in 1991, there was a steady downward trend in cultivated land throughout the study region. From 1970–1987 to 2005–2017, the region lost about 39% of its croplands. Moreover, the most significant relative reduction in cultivated land was noted in the forest zone (south taiga, mixed and broadleaf forests) and the dry steppes and the semi-desert of the Caspian Lowland—about 53% and 65%, respectively. These territories are with climatically risky agriculture and less fertile soils. There was also a widespread reduction in agricultural machinery on croplands and livestock on pastures of the region. A decrease in soil/gully erosion rates over the past decades was also revealed based on state hydrological monitoring data on river suspended sediment load as one of the indicators of the temporal variability of erosion intensity in river basins and the published results of some field research in various parts of the studied landscape zones. The most significant reduction in the intensity of erosion and the load of river suspended sediment was found in European Russia’s forest-steppe zone. This was presumably due to a favorable combination of the above changes in land cover/use and climate change.

Restoring Nature at Lower Food Production Costs

Growing competition for land, water and energy call for global strategies ensuring affordable food production at minimum environmental impacts. Economic modelling studies suggest trade-off relationships between environmental sustainability and food prices. However, evidence based on empirical cost-functions supporting such trade-offs remains scarce at the global level. Here, based on cost engineering modelling, we show that optimised spatial allocation of 10 major crops, would reduce current costs of agricultural production by approximately 40% while improving environmental performance. Although production inputs per unit of output increase at local scales, a reduction of cultivated land of 50% overcompensates the slightly higher field-scale costs enabling improved overall cost-effectiveness. Our results suggest that long-run food prices are bound to continue to decrease under strong environmental policies. Policies supporting sustainability transitions in the land sector should focus on managing local barriers to the implementation of high-yield regenerative agricultural practices delivering multiple regional and global public goods.

Assessment of Land-Use/Cover Changes and Its Ecological Effect in Rapidly Urbanized Areas—Taking Pearl River Delta Urban Agglomeration as a Case

Based on the land-use data of 2000 and 2015, this study makes a quantitative analysis of the ecological environment effect in Pearl River Delta using the ecological environment quality index and the ecological contribution rate of land-use change types. The results showed the following: (1) During 2000–2015, the land-use changes in Pearl River Delta mainly manifested in the reduction of cultivated land, forest land, water area, and unused land, while the area of construction land and grassland showed an increasing trend. The quality of ecological environment in the Pearl River Delta was largely stable but slightly declined overall; (2) Over the past 15 years, the comprehensive ecological environment index of the Pearl River Delta urban agglomeration has decreased by 0.02. With an average annual decrease of 0.11%. The spatial expansion caused by urbanization had the most profound impact on the decline of the ecological environment quality in the Pearl River Delta; (3) The eco-environmental quality indices of various cities in the Pearl River Delta declined to varying degrees. The city with the largest decline was Dongguan, followed by Shenzhen and Zhongshan. The spatial differentiation characteristics of the eco-environmental quality index indicate that the ecological quality preferences of cities distributed around the study area and close to the inland areas, while the ecological quality of the central coastal cities are biased. The quality of the ecological environment is related to the basis of the regional ecological environment. The research results have important practical significance for maintaining regional ecological balance and promoting the sustainable use of land resources, and they provide a reference for the study of the ecological and environmental effects of land-use changes in key cities in economically developed areas.

Cultivated land protection and rational use in China

Cultivated land protection is an important way to ensure food security, social stability and sustainable development. As one of the main causes of cultivated land loss, the spatio-temporal pattern of illegal cultivated land use and driving forces have not been systematically investigated. This study first reviewed the evolution of China’s cultivated land protection policy in the past four decades, then used spatial analysis technology to explore the spatio-temporal patterns of China’s illegal cultivated land use, and finally applied an econometric model to assess the impact of population growth, economic development and rising housing prices on illegal cultivated land use at the national and regional levels based on the balanced provincial panel data from 1999 to 2017. The results show that in the past 40 years, China has attached great importance to the protection of cultivated land, and established a relatively perfect cultivated land protection system. The quantity of cultivated land in China kept a dynamic balance on the whole, but the quality of cultivated land has dropped sharply, and regional human-land conflicts has become prominent. The driving forces of cultivated land loss in China varied across regions. Illegal use of cultivated land was also one of the important driving forces of cultivated land reduction in China. The number of illegal land use cases and the area appropriated have experienced a process of first increase and then decrease over the past two decades. The accumulated cases and area of illegal farmland use in the eastern region were larger than that in the central and western regions, but both showed a rapid downward trend over the past two decades, demonstrating that the illegal use of cultivated land in eastern China has been controlled to a certain extent. Population growth and land urbanization have a significant positive impact on illegal cultivated land use area in China and its three regions, while economic development has not driven but curbed illegal land use. The rise of commercial housing prices has no significant impact on illegal farmland use in rural China. We proposed measures to further control the illegal use of cultivated land, and believed that it is necessary and urgent to stop illegal occupation of cultivated land from the source

Monitoring Land Cover Change on a Rapidly Urbanizing Island Using Google Earth Engine

Island ecosystems are particularly susceptible to climate change and human activities. The change of land use and land cover (LULC) has considerable impacts on island ecosystems, and there is a critical need for a free and open-source tool for detecting land cover fluctuations and spatial distribution. This study used Google Earth Engine (GEE) to explore land cover classification and the spatial pattern of major land cover change from 1990 to 2019 on Haitan Island, China. The land cover classification was performed using multiple spectral bands (RGB, NIR, SWIR), vegetation indices (NDVI, NDBI, MNDWI), and tasseled cap transformation of Landsat images based on the random forest supervised algorithm. The major land cover conversion processes (transfer to and from) between 1990 and 2019 were analyzed in detail for the years of 1990, 2000, 2007, and 2019, and the overall accuracies ranged from 88.43% to 91.08%, while the Kappa coefficients varied from 0.86 to 0.90. During 1990–2019, other land, cultivated land, sandy land, and water area decreased by 30.70%, 13.63%, 3.76%, and 0.95%, respectively, while forest and built-up land increased by 30.94% and 16.20% of the study area, respectively. The predominant land cover was other land (34.49%) and cultivated land (26.80%) in 1990, which transitioned to forest land (53.57%) and built-up land (23.07%) in 2019. Reforestation, cultivated land reduction, and built-up land expansion were the major land cover change processes on Haitan Island. The spatial pattern of forest, cultivated land, and built-up land change is mainly explained by the implementation of a ‘Grain for Green Project’ and ‘Comprehensive Pilot Zone’ policy on Haitan Island. Policy and human activities are the major drivers for land use change, including reforestation, population growth, and economic development. This study is unique because it demonstrates the use of GEE for continuous monitoring of the impact of reforestation efforts and urbanization in an island environment.

Response of the parameters of excess infiltration and excess storage model to land use cover change

Abstract The Loess Plateau is the main source of water in Yellow River, China. After 1980s, the Yellow river water presented a significant reduction, what caused the decrease of the Yellow river discharge had been debated in academic circles. We proceeded with runoff generation mechanisms to explain this phenomenon. We built saturation excess runoff and infiltration excess runoff generation mechanisms for rainfall–runoff simulation in Jingle sub-basin of Fen River basin on the Loess Plateau, to reveal the influence of land use change on flood processes and studied the changes of model parameters under different underlying conditions. The results showed that the runoff generation mechanism was mainly infiltration-excess overland flow, but the flood events of saturation-excess overland flow had an increasing trend because of land use cover change (the increase of forestland and grassland areas and the reduction of cultivated land). Some of the model parameters had physical significances，such as water storage capacity (WM), infiltration capacity (f), evapotranspiration (CKE), soil permeability coefficient (k) and index of storage capacity distribution curve (n) showed increasing trends, and index of infiltration capacity distribution curve (m) showed a decreasing trend. The above results proved the changes of runoff generation mechanism from the perspective of model parameters in Jingle sub-basin, which can provide a new perspective for understanding the discharge reduction in the Yellow River basin.

Spatio-temporal variations of ecosystem services in the urban agglomerations in the middle reaches of the Yangtze River, China

Increasing human activities have notably altered the compositions of global ecosystems, and consequently the services provided by them. As one of the most important economic functional areas in China, Urban Agglomerations in the middle reaches of the Yangtze River (UAMRYR) has undergone dramatic land use changes due to the rapid urbanization over recent decades. In this study, we utilized a revised proxy-based approach to evaluate ecosystem services value (ESV), applied the ecological contribution degree to quantify the response of ESV to land use change, coupled with RDA to explore the socioeconomic forces of ecosystem services. Our findings showed that land use activities were more intensive during 2010–2018 than that in 2000–2010. The total ESV decreased by $4.58 billion and most of the ecological functions exacerbated due to the expansion of built-up land and the reduction of cultivated land during 2010–2018. Besides, based on RDA result, park green land per capita, population density, and distance from the central city were estimated as the top three frontal factors affecting ESV; yet per capita water consumption was a negative one. Therefore, different development strategies should be adopted along the altitude gradient in UAMRYR. That is to emphasize the protection of permanent cultivated land and the diversification of land composition in low altitude areas, while ecological protection should be strengthened in higher areas. Understanding how ecosystem services respond to LUCC and socioeconomic drivers can help to enhance ecosystem functions and provide a theoretical basis for the construction of ecological civilization of UAMRYR, which may also be applied at the other urban agglomerations around the globe.

Spatiotemporal Dynamics of Carbon Storage in Response to Urbanization: A Case Study in the Su-Xi-Chang Region, China

Terrestrial ecosystem carbon storage plays an important role in mitigating global warming. Understanding the characteristics and drivers of changes in carbon storage can provide a scientific basis for urban planning and management. The objective of this study was to reveal the ways in which urbanization influences the spatial and temporal variations in carbon storage. In this study, we investigated the changes in carbon storage from 1990–2000, 2000–2010, and 2010–2018 in the Su-Xi-Chang region, which is a typical fast-growing urban agglomeration in China, based on the InVEST (Integrated Valuation of Ecosystem Services and Tradeoffs) model. Moreover, we analyzed the impacts of urbanization-induced land-use changes on carbon storage. The results showed that in terms of space and time, the greatest loss of carbon storage occurred in developing urban areas and during the rapidly urbanizing stage. Our study revealed that the reduction in cultivated land was the greatest contributor to carbon stock losses. In addition, we found that some types of land use conversion can enhance carbon storage. Based on the results, some suggestions are proposed aimed at promoting urban sustainable development. This study also provides insights into enhancing urban sustainability for other urban agglomerations throughout the world.