Land use and cover change and influencing factor analysis in the Shiyang River Basin,China

Land use and cover change(LUCC)is the most direct manifestation of the interaction between anthropological activities and the natural environment on Earth's surface,with significant impacts on the environment and social economy.Rapid economic development and climate change have resulted in significant changes in land use and cover.The Shiyang River Basin,located in the eastern part of the Hexi Corridor in China,has undergone significant climate change and LUCC over the past few decades.In this study,we used the random forest classification to obtain the land use and cover datasets of the Shiyang River Basin in 1991,1995,2000,2005,2010,2015,and 2020 based on Landsat images.We validated the land use and cover data in 2015 from the random forest classification results(this study),the high-resolution dataset of annual global land cover from 2000 to 2015(AGLC-2000-2015),the global 30 m land cover classification with a fine classification system(GLC_FCS30),and the first Landsat-derived annual China Land Cover Dataset(CLCD)against ground-truth classification results to evaluate the accuracy of the classification results in this study.Furthermore,we explored and compared the spatiotemporal patterns of LUCC in the upper,middle,and lower reaches of the Shiyang River Basin over the past 30 years,and employed the random forest importance ranking method to analyze the influencing factors of LUCC based on natural(evapotranspiration,precipitation,temperature,and surface soil moisture)and anthropogenic(nighttime light,gross domestic product(GDP),and population)factors.The results indicated that the random forest classification results for land use and cover in the Shiyang River Basin in 2015 outperformed the AGLC-2000-2015,GLC_FCS30,and CLCD datasets in both overall and partial validations.Moreover,the classification results in this study exhibited a high level of agreement with the ground truth features.From 1991 to 2020,the area of bare land exhibited a decreasing trend,with changes primarily occurring in the middle and lower reaches of the basin.The area of grassland initially decreased and then increased,with changes occurring mainly in the upper and middle reaches of the basin.In contrast,the area of cropland initially increased and then decreased,with changes occurring in the middle and lower reaches.The LUCC was influenced by both natural and anthropogenic factors.Climatic factors and population contributed significantly to LUCC,and the importance values of evapotranspiration,precipitation,temperature,and population were 22.12%,32.41%,21.89%,and 19.65%,respectively.Moreover,policy interventions also played an important role.Land use and cover in the Shiyang River Basin exhibited fluctuating changes over the past 30 years,with the ecological environment improving in the last 10 years.This suggests that governance efforts in the study area have had some effects,and the government can continue to move in this direction in the future.The findings can provide crucial insights for related research and regional sustainable development in the Shiyang River Basin and other similar arid and semi-arid areas.

Analysis on the land use and cover change in Tianjin Binhai New Area based on the remote sensing

This paper carries out quantitative analysis on the land use/cover （LU/C） change of 13anjin Binhai New Area in recent 10 years through using land use transition matrix from the three-stage LU/C classification maps of 2000, 2005 and 2010 drafted by means of the National Land Classification System of China based on Landsat TM satellite remote sensing image and the Tianjin Binhai New Area 1：50 000 relief maps. On this basis, the impact of such driving factors as the economy and population on LU/C is further analyzed. The results show that the area of the building land in Binhai New Area has increased significantly over the ten years, and the greenland, wetland, and shoals of high ecological value have been dramatically transformed into the building land and unused land for the development and construction, and the change is more significant in the later five years.

Exploring the Spatiotemporal Changes and Driving Forces of Ecosystem Services of Zhejiang Coasts,China,Under Sustainable Development Goals

Ecosystem services(ESs)refer to the continuous provisioning of ecosystem goods and services that benefit human beings.Over recent decades,rapid urbanization has exerted significant pressure on coastal ecosystems,resulting in biodiversity and habitat loss,environmental pollution,and the depletion of natural resources.In response to these environmental challenges,the Sustainable Development Goals(SDGs)were proposed.Given the pressing need to address these issues,understanding the changes in ESs under the SDGs is crucial for formulating specific ecological strategies.In this study,we first analyzed land use and cover change in the Zhejiang coasts of China during 2000–2020.Then,we investigated the spatiotemporal configuration of ESs by integrating carbon storage(CS),soil retention(SR),habitat quality(HQ)and water yield(WY)using the Integrated Valuation of Ecosystem Services and Tradeoffs(InVEST)model.The driving mechanisms of ESs,which varied by space and time,were also explored using the Geo-detector method.The results revealed that,over the past two decades:1)the Zhejiang coasts have experienced a significant increase of 2783.72 km^(2) in built-up land areas and a continuous decrease in farmland areas due to rapid urbanization;2)owing to higher precipitation,extensive vegetation cover,and reduced anthropogenic disturbances,forests emerge as a crucial land use type for maintaining ecosystem services such as HQ,CS,WY,and SR;3)ESs have generally declined across the entire Zhejiang coasts,with a significant decrease observed in the northern areas and an increase in the southern areas spatially;4)the expansion of built-up land areas emerged as the primary factor affecting ecosystem services,while the vegetation factor has been increasingly significant and is expected to become predominant in the near future.Our study provides insights of understanding of ecosystem service theory and emphasizing the importance of preserving biodiversity for long-term sustainable development,and valuable scientific references to support the ecological management decision-making for local governments.

Land-use changes in the small watershed of the Loess Plateau,hilly-gully region, China

As more and more farmland is converted to forestry, the need for effective decision support regarding the use of land in the fragile ecological environment of the Loess Plateau hilly-gully area. The Luoyugou watershed was chosen as the study area to calculate the single dynamic degree, integrated dynamic degree, and change indexes of land use, as well as the land-use type transition matrix. This was done by interpreting the TM and SPOT images of the Luoyugou watershed in 1986, 1995, and2004 and making statistical analysis. The results of ou statistical analysis show that the conversion of slope farm land to terrace and forest land plays a dominant role in land-use changes in the Luoyugou watershed from 1986 to2004. The land-use changes are mainly driven by popula tion growth, socio-economic development, consume spending, and investment in forest ecology.

Evaluation of carbon emissions associated with land use and cover change in Zhengzhou City of China

Studies on carbon emissions associated with land use and cover change(LUCC)are key to understanding the impact of human activities on regional sustainability.In this study,we analyzed the temporal and spatial changes in carbon emissions associated with LUCC for production,living,and ecological spaces in Zhengzhou City of China.Landsat remote sensing images were used to classify the land use and land cover(LULC)types in Zhengzhou City in 1988,2001,2009,and 2015.Carbon emissions associated with LUCC were evaluated using a spatial gradient model and the niche mechanism.It was found that during 1988-2015,carbon emissions associated with LUCC in Zhengzhou City increased by 17.1×10^(6) t,while the carbon sink resulted from cultivated land,forests,water bodies,and unused land decreased significantly.Most of the increase in carbon emissions associated with LUCC occurred in the center of the city.The peak carbon emissions were located in the northeastern,southeastern,northwestern,and southwestern regions of Zhengzhou City,and carbon emissions varied considerably in the different spatial gradient rings over time.Among the three spaces,carbon emissions associated with LUCC were mainly affected by the living space.The population size and population urbanization rate were negatively correlated with the ecological space and positively correlated with the production and living spaces.Our results highlight that Zhengzhou City should take the new urbanization path of urban transformation development and ecological civilization construction to ensure the realization of the promised carbon emission reduction targets.

LUCC （Land Use and Cover Change） and the Environmental-Economic Accounts System in Brazil

The objective of this work is to produce statistics that are going to show changes occurred in Brazil＇s ecosystems and these statistics are going to join the SEEA （Environmental-Economic Accounts System）. It is based by a SEEA＇s methodology, diffused by UN （United Nations）, which aims an approach between economic and environmental statistics, producing international comparability and conceptual uniformity to evaluate change process in land cover and land use that occurs in several countries. It is necessary to verifying the suitability of methodological procedures to Brazilian reality and the access to all information and files needed. The first step was analysing MODIS （Moderate Resolution Imaging Spectroradiometer） as orbital instrument on the purposed classification method. The choice of this sensor was made because of the product＇s quality and its capacity to generate images of a large area, though the challenge is to identify accurate Land usage＇s categories in images with a spatial resolution of approximately 250 m. After the final classification, the next step is to make a quantification and comparison of data from these different years using a 1 km2 grids, as proposed in an already used methodology by the European Environment Agency. This procedure will allow evaluate and identify the process of changing in each grid of the land cover and land use, and provide historical series of the chosen years.

A Distributed Monthly Water Balance Model for Analyzing Impacts of Land Cover Change on Flow Regimes

The Miyun Reservoir is the most important water source for Beijing Municipality, the capital of China with a population of more than 12 million. In recent decades, the inflow to the reservoir has shown a decreasing trend, which has seriously threatened water use in Beijing. In order to analyze the influents of land use and cover change (LUCC) upon inflow to Miyun Reservoir, terrain and land use information from remote sensing were utilized with a revised evapotranspiration estimation formula; a water loss model under conditions of human impacts was introduced; and a distributed monthly water balance model was established and applied to the Chaobai River Basin controlled by the Miyun Reservoir. The model simulation suggested that not only the impact of land cover change on evapotranspiration, but also the extra water loss caused by human activities, such as the water and soil conservation development projects should be considered. Although these development projects were of great benefit to human and ecological protection, they could reallocate water resources in time and space, and in a sense thereby influence the stream flow.

The impact of cropland conversion on environmental effect in the Loess Plateau: a pilot study based on the national experimental bases

Conversion of cropland to forestry and grassland is an important method to reduce soil erosion and improve the biophysical environment in the Loess Plateau. The feasibility, methods, and environmental effects of cropland conversion were studied based on 11 typical watersheds of national experimental bases instead of different geographic areas of the Loess Plateau. Between 1986 and 2000, cropland, sloping cropland and non-agricultural land decreased by 8%, 92.5% and 8% respectively, while forestry increased by 15.7%. The land use change not only decreased annual soil erosion by 74%, but also increased vegetation coverage by 100% and improved the soil condition and biodiversity. This can be achieved by building basic farmland, increasing capital and scientific input, and planting trees and grasses according to the natural biophysical restrictions.

Effects of land use and changes in cover on the transformation and transportation of iron:A case study of the Sanjiang Plain,Northeast China

Wetland reclamation has been ongoing in the Sanjiang Plain since the mid-1950s,which has resulted in major changes in wetlands and the agriculture ecosystem in the region that have influenced the iron output to the Sea of Okhotsk and limited the primary productivity in the North Pacific Ocean.This study was conducted to investigate the chemical forms of iron in different aquatic environments(agricultural water including groundwater,paddy water,and canal water;wetland water including marsh water,marsh streams,and main streams) with the cross-flow filtration method to reveal the transportation and transformation characteristics of iron in response to major land use changes.In addition,the factors affecting iron behavior in different water bodies were reviewed.In marsh water and streams,the concentrations of dissolved iron were higher due to the high organic matter contents and marsh water becoming the main iron source for river water.The conversion of dissolved iron into acid-labile iron occurred during the discharge of wetland water into marsh rivers.Iron primarily existed in both the >0.7 and <0.01 μm size fractions,accounting for about 58.3% and 26.4% of the total dissolved iron,respectively.In agricultural irrigation systems,ferrous ion entered the paddy fields from groundwater,and a fraction of this ferrous iron was subsequently converted into high molecular weight and medium molecular weight iron(colloid iron) in paddy and canal water.However,the concentrations of total dissolved iron decreased by 62.5% from underground to the surface due to the formation of precipitates.Despite this,water discharge in agriculture is still an important iron source for rivers and has the potential to supplement iron due to its higher acid-labile iron concentrations.Land use and cover change and agricultural irrigation increased the iron content of surface soil,but reduced the output of iron in water systems.Overall,the concentration of total dissolved iron in water systems has been reduced to 42.6% by wetland reclamation.

Terrestrial Near-Surface Wind Speed Variations in China:Research Progress and Prospects

Changes in terrestrial near-surface wind speed(NSWS)are indicative of the concentrated net effect of climate change and anthropogenic activities.Investigating change mechanisms of NSWS not only furthers the understanding of how the atmosphere changes and improves the climate analysis and projection,but also aids the evaluation and application of wind energy resources.Recent advances in studies of the changes and associated mechanisms of the NSWS over China are reviewed in this paper.Some new results have been achieved in understanding the behaviors of the NSWS changes.The NSWS over China has experienced a decrease in the past 40 years and a recovery in the recent decade,exhibiting large regional and seasonal differences.Understanding of the mechanisms of the NSWS changes has been improved in several aspects;for example,it is found that the reduced NSWS over China is due to the weakening of the pressure-gradient force(PGF)attributed to variations in large-scale ocean–atmosphere circulations(LOACs)as well as the increase of surface roughness due to the land use and cover change(LUCC).The main methods used to analyze the NSWS changes and corresponding mechanisms are also elucidated and discussed.However,studies are still lacking on the mechanisms for multi-timescale(seasonal,interannual,decadal,multidecadal)variations in the NSWS over China,and it remains unknown about the contributions of different forcing factors to the NSWS changes.Finally,key scientific issues regarding our understanding of the NSWS changes are proposed for future investigation.

Estimates of Variation in Chinese Terrestrial Carbon Storage Under an Environmental Conservation Policy Scenario for 2000-2025

Policies always have strong impacts on land-use and land-cover change （LUCC）,and thus indirectly affect the terrestrial carbon balance.In this paper,land use change from 2010 to 2025 in China was simulated with the Dynamics Land System （DLS） under an environmental conservation policy scenario,and the projected effect of this policy scenario on Chinese terrestrial carbon storage was evaluated.Under the simulation,forest coverage will increase by 23% while cropland and grassland will decrease by 37% and 11% respectively.Due to the large expansion of forest coverage,the forest carbon storage will have an accumulation of 66.0 Tg C y-1.This will take place mainly in central China in a band from the northeast to southwest.Grasslands,however,will be a carbon source of 5.7 Tg C y-1 in the same period as a result of the transformation of grassland to woodlands or deserts.As the carbon storage capacity of forest soil is considerably higher than that of grassland and cropland,such LUCC will eventually result in a soil carbon accumulation of 13.3 Tg C y-1.From 2000 to 2025,the carbon storage of Chinese terrestrial ecosystem is likely to increase by 1.8 Pg C,and thus the terrestrial ecosystem will be a carbon sink of 0.074 Pg C y-1,89.6% of which will result from an increase in forest carbon storage.