Changes In Land Use Types Research Articles

Spatial and temporal variations of vegetation cover and its influencing factors in Shandong Province based on GEE.

Economic development has rapidly progressed since the implementation of reform and opening up policies, posing significant challenges to sustainable development, especially to vegetation, which plays a crucial role in maintaining ecosystem service functions and promoting green low-carbon transformations. In this study, we estimated the fractional vegetation cover (FVC) in Shandong Province from 2000 to 2020 using the Google Earth Engine (GEE) platform. The spatial and temporal changes in FVC were analyzed using gravity center migration analysis, trend analysis, and geographic detector, and the vegetation changes of different land use types were analyzed to reveal the internal driving mechanism of FVC changes. Our results indicate that vegetation cover in Shandong Province was in good condition during the period 2000 to 2020. The high vegetation cover classes dominated, and overall changes were relatively small, with the center of gravity of vegetation cover generally shifting towards the southwest. Land use type, soil type, population density, and GDP factors had the most significant impact on vegetation cover change in Shandong Province. The interaction of these factors enhanced the effect on vegetation cover change, with land use type and soil type having the highest degree of influence. The observational results of this study can provide data support for the policy makers to formulate new ecological restoration strategies, and the findings would help facilitate the sustainability management of regional ecosystem and natural resource planning.

China’s National Park Construction Contributes to Carbon Peaking and Neutrality Goals

The official establishment of China’s national parks marks a new stage in the construction of China’s ecological civilization system. National parks systematically protect the areas with the richest biodiversity and the most complete ecosystem processes in China. This is beneficial not only for China’s natural conservation work, but also for the world’s response to environmental issues, such as climate change. Based on remote sensing images of land use in the four periods 1990, 2000, 2010, and 2020, this study calculated the land use changes in each national park during the corresponding period. Using the Plus model LEAS module, the driving factors of land use change in the national parks were studied and explored. In addition, the study used the InVEST model carbon storage module, using remote sensing images from different periods and the corresponding carbon pools of each national park as the basic data for model operation, to obtain the carbon storage changes in each national park over the past 30 years. Based on the hotspot analysis function, the hotspot areas of carbon storage changes in the national parks in the past 30 years were determined. Consequently, based on the CARS module of the PLUS model, the carbon storage in Northeast Tiger and Leopard National Park in 2030 was estimated under different scenarios. Research suggested that, except for Sanjiangyuan National Park where grassland is the main land use type, the other four national parks are all dominated by forests, and the expansion and changes in the main land use types were due to human activities. In the past 30 years, the carbon storage in China’s national park ecosystem has mainly shown a trend of first increasing and then gradually decreasing. Based on the changes in carbon storage in the national park, restoration scenarios were simulated for the core protected and generally controlled areas of Northeast Tiger and Leopard National Park. Under the ideal scenario, the highest value of carbon storage would be achieved by 2030, which would be 7,468,250 t higher than that in 2020. The present study provides a reference for the regional management of China’s national parks and further confirms that the implementation of the national park system can enhance China’s ability to achieve carbon peaking and neutrality goals.

Analysis of spatiotemporal heterogeneity and influencing factors of soil erosion in a typical erosion zone of the southern red soil region, China

The southern red soil region (SRSR) of China, a region that is environmentally sensitive, suffers severe soil erosion (SE) as a result of climate change and human activity. The factors driving SE changes in the SRSR of China under changing settings have, however, only been the subject of a small number of research. Changting County is a typical SE area in the SRSR of China. The spatiotemporal variation characteristics of SE in Changting County from 2000 to 2020 were investigated using the revised universal soil loss equation (RUSLE), while the dominant factors influencing the spatiotemporal dynamic change of SE were analyzed using the optimal parametric geographical detector (OPGD) and logarithmic mean Divisia Index (LMDI). The results showed that the average annual soil erosion modulus in Changting County shows a decreasing trend, with the SE modulus decreased from 10.00 t·hm−2·a−1 in 2000 to 3.38 t·hm−2·a−1 in 2020. Slight SE intensity was the dominant SE class, accounting for more than 75% of the total area, and the proportion is trending upwards. Natural and anthropogenic factors showed significant effects on the spatial variation of SE, of which land use and vegetation cover were the main factors influencing the spatial distribution of SE. Furthermore, the interaction between these two dominant factors explained greatly the spatial variation of SE. The mitigation of SE was mainly attributed to the increase in vegetation cover following the implementation of various ecological projects, contributing to the reduction of SE by 68.7%. In addition, the changes in land use types and rainfall amounts also played positive roles in reducing SE, showing contributions of 20.2% and 11.1%, respectively.

The salinization process and its response to the combined processes of climate change–human activity in the Yellow River Delta between 1984 and 2022

Within the context of global change, the evolution of salinization in the Yellow River Delta has undergone dramatic changes. However, it is not clear how it responds to the combined processes of climate change and human activity（reclamation projects, changes in land-use types, and increases in fertilizer use）Based on the optimal soil salinization monitoring index model, this study retrieved the annual time series data set for salinization from 1984 to 2022 and then analyzed the spatial and temporal evolution patterns of salinization in the modern Yellow River Delta. The mechanism of the response of salinization evolution to climate change and human activities was investigated using Geodetector. The main conclusions were as follows: (1) From 1984 to 2022, the salinization intensity in the northeastern coastal zone of the Yellow River Delta showed an increasing trend, while that in the southwestern inland area showed an improving trend. (2) The high-frequency salinization zones were mainly concentrated near the mainstream and tributaries of the Yellow River, while zones with desalinization, re-salinization, and new salinization zones were mainly distributed in the main stream of the Yellow River. (3) There were obvious differences in the dominant factors in the evolution of salinization in different historical periods. In 1984, soil component factors and vegetation coverage were the dominant factors in the evolution of salinization. In 2022, vegetation coverage and land-use types had the strongest explanatory power for the salinization process. (4) The influence of natural and human activity factors on the salinization process was not independent, but a mutually reinforcing process. The interaction between NDVI and other factors has dominated the evolution of salinization in the Yellow River Delta. From 1984 to 2022, human activities were the dominant factors that promoted the improvement or intensification of salinization in the region.

Global analysis of land-use changes in karst areas and the implications for water resources

Karst areas contain valuable groundwater resources and high biodiversity, but are particularly vulnerable to climate change and human impacts. Land-use change is the cause and consequence of global environmental change. The releases of the Climate Change Initiative-Land Cover (CCI-LC) and World Karst Aquifer Map (WOKAM) datasets have made it possible to explore global land-use changes in karst areas. This paper firstly analyses the global karst land-use distribution in 2020, as well as the land-use transition characteristics between 1992 and 2020. Then, two indicators, proportion of land-use change and dominant type of land-use change, are proposed to identify the spatial characteristics of land-use change in global karst areas. Finally, three examples of land-use change in karst areas are analyzed in detail. Land-use types and proportions of the global karst areas from large to small are as follows: forest (31.78%), bare area (27.58%), cropland (19.02%), grassland (10.87%), shrubland (7.21%), wetland (1.67%), ice and snow (1.16%) and urban (0.71%). The total area of global karst land-use change is 1.30 million km2, about 4.85% of global karst surface. The land-use change trend of global karst is dominated by afforestation, supplemented by scattered urbanization and agricultural reclamation. The tropical climate has a higher intensity of land-use change. Regions of agricultural reclamation are highly consistent with the population density. These results reflect the impact of human activities and climate change on land-use changes in global karst areas, and serve as a basis for further research and planning of land resource management.

Assessment of Physico-chemical Properties of Soil from Different Blocks of West Godavari District, Andhra Pradesh, India

The study of nutrient status in West Godavari District of Andhra Pradesh was carried out in 2022-2023. Representative soil samples were collected covering three mandalas of West Godavari division before sowing of crop. The soil samples were analysed for their Physico-chemical Properties. The samples were taken from different blocks and depths like 0-15cm,15-30cm and 30-45cm. There are many reasons leading to soil quality deterioration, including changes in land use types from forest to arable land and the consequences from intensive land use. The colour of soil changes between the three depths at all the locations. There was also a difference in colour of dry and wet soils was dark brown to dark yellowish brown. Results show that soil Bulk Density varied from 1.31 to 1.48 % Mg m-3, soil Particle Density varied from 2.44 to 2.57 % Mg m-3, Percent of Pore Space from 43.09 to 48.21 %, Water Holding Capacity from 35.73 to 44.24 % respectively. Soil pH varied from 77.25 to 8.92 % and EC is 0.18 to 0.37 % respectively while soil Organic Carbon varied from 0.28to 0.55 % and Available Nitrogen varied from low to medium i.e., 216 to 323 % kg ha-1 Available Phosphorous varied from medium to high range i.e., 14.05 to 25.71 % kg ha-1. and Available Potassium was found to be medium range i.e.,137.00 to 236.00 % kg ha⁻1, Exchangeable Calcium and Magnesium low from 3.34 to 5.66 % (meq 100g-1) and 1.36 to 2.74 % (meq 100g-1) respectively. Results show that the soil samples of the areas of Eluru division were found to be mildly alkaline and non-saline.

Evaluation and Tradeoff of Ecosystem Services in Jiaozuo

With the continuous development of the economy and society, the demand for land space for human survival has also increased, which means that the pressure on ecosystem services has also been unprecedentedly high, leading to serious problems such as ecological environment deterioration and system function decline, resulting in fierce conflicts between ecological environment protection and human social development. Therefore, the relationship between ecosystem services and economic and social development has become a hot research topic in the field of land ecology. Jiaozuo City is also facing the problem of ecological degradation. In order to achieve coordinated development of ecology, society, and economy, this article analyzes the spatiotemporal changes in land use/cover in Jiaozuo City from 1995 to 2020. The InVEST model is used to evaluate four types of ecosystem services in Jiaozuo City: water production, carbon storage, soil conservation, and nutrient output; Summarize and summarize the spatiotemporal distribution characteristics and evolution laws of ecosystem services, and explore the trade-off and synergistic relationships between ecosystem service functions and their driving factors. The research results indicate that: (1) The main types of land use/cover in Jiaozuo City are arable land (64.5%), forest land (approximately 9.9%), grassland (1.1%), water area (0.6%), and construction land (23.8%). The changes in land use types are relatively small. (2) From 1995 to 2020, the biomass and spatial distribution evolution of the four ecosystem services in Jiaozuo City varied. There are significant interannual differences in water production services, and the spatial distribution of water production in the western region is lower than that in the eastern region. The southern region is lower than the northern region. The interannual variation of nutrient (phosphorus) output is relatively small, and the spatial distribution pattern varies greatly, showing a high and low value clustering distribution pattern. The interannual difference in soil conservation is relatively small. The interannual differences in carbon storage are small, and the annual spatial distribution is irregular. (3) Each ecosystem service is influenced by different natural and social influencing factors, and the contribution rate of natural factors is higher than that of social factors. There is a significant difference in the output capacity of ecosystem services among different land uses/covers, which directly affects the total amount and spatial distribution of ecosystem services. The ecological status of Jiaozuo City is worrying. In the future socio-economic development process, reasonable planning of land use should be carried out to vigorously ensure the parallel and healthy development of social economy and ecological environment.

Impact of expanded built-up land on ecosystem service value by considering regional interactions

During rapid economic development and urbanisation, land expansion in built-up areas is China's dominant land-use change type, resulting in the loss of ecosystem service value (ESV). Economic development is China's main driving force for built-up land expansion. Under the trend of the spatial separation of production and consumption, expanded built-up land embodied in trade flows between regions as a scarce land resource. Through trade, a region can indirectly use built-up land from outside areas, which may affect land use within the user and provider regions. Regional ESV loss may be affected by outer regions, although previous studies have seldom considered it. Accordingly, this study quantified ESV for the whole of China in high resolution and determined ESV loss caused by expanded built-up land for each province and ESV loss flows embodied in interregional interactions. The results found that China's total ESV of terrestrial ecosystems was 37.44 trillion yuan in 2015, and the expanded built-up land resulted in a loss of 13.7 billion yuan in ESV. Due to the north–south differences in natural and economic levels in China, there was significant spatial heterogeneity in ESV and ESV loss caused by built-up land expansion, with the high-value areas mainly in the southern coastal areas. With regional interaction, the leading regional flow direction of built-up land and ESV loss was from north to south, mainly from economically developing regions to economically developed regions. However, there was a discrepancy between the actual users of the built-up land and the ESV loss-bearers. Evident regional inequalities existed in several provinces with regional interactions. Overall, this study provides a reference for developing China's interregional economic and ecological harmony strategies in the context of sustainable development.

Evolution of Urban Ecosystem Service Value and a Scenario Analysis Based on Land Utilization Changes: A Case Study of Hangzhou, China

Simulating the change in ecosystem service values (ESVs) caused by land use changes in metropolitan areas under multiple scenarios is of great significance to ensure regional ecological security and sustainable urban development. This study assessed the variations in land use and ESV in the main urban area of Hangzhou, China, from 2000 to 2020. A total of four future land use scenarios for 2030 were created using the cellular automata–Markov prediction model and ESVs were calculated for four future scenarios. The results are as follows: (1) Arable land and construction land were the most drastic types of land use changes in the main urban area of Hangzhou during the study period. From 2000 to 2020, construction land in the main urban area of Hangzhou expanded rapidly, with an increase of 46,916.82 hm2, while the cultivated land area decreased significantly by 38,396.43 hm2. (2) The ESV in the study area continuously declined from 2000 to 2020, with high-value ecosystem service areas predominantly found in forest areas and water areas. (3) The values of ecosystem services under the simulated future scenarios of natural development, rapid development, planned development, and ecological development were CNY 15.053, 14.525, 16.690, and 16.799 billion, respectively. The planned development and ecological development scenarios effectively ensure a high ESV. The results indicated that balancing various types of land use is essential to guarantee ecological security in urban development. Moreover, urban development and construction should be undertaken in areas with a low ESV. This forecasting study can serve as a key reference for policy makers regarding the urban landscape sustainability of Hangzhou City. The integrated simulation method of land use and ESV proposed in this study can shed light on the urban spatial layout and spatial regulation in urban land use planning.

Strategy for cost-effective BMPs of non-point source pollution in the small agricultural watershed of Poyang Lake: A case study of the Zhuxi River

In recent years, Poyang Lake has been affected by severe agricultural non-point source (NPS) pollution, a global water pollution problem. The most recognized and effective control measure for agricultural NPS pollution is the strategic selection and placement of best management practices (BMPs) for critical source areas (CSAs). The present study employed the Soil and Water Assessment Tool (SWAT) model to identify CSAs and evaluate the effectiveness of different BMPs in reducing agricultural NPS pollutants in the typical sub-watersheds of the Poyang Lake watershed. The model performed well and satisfactorily in simulating the streamflow and sediment yield at the outlet of the Zhuxi River watershed. The results indicated that urbanization-oriented development strategies and the Grain for Green program (returning the grain plots to forestry) had certain effects on the land-use structure. The proportion of cropland in the study area decreased from 61.45% (2010) to 7.48% (2018) in response to the Grain for Green program, which was mainly converted to forest land (58.7%) and settlements (36.8%). Land-use type changes alter the occurrence of runoff and sediment, which further affect the nitrogen (N) and phosphorus (P) loads since sediment load intensity is a key factor affecting the P load intensity. Vegetation buffer strips (VBSs) proved the most effective BMPs for NPS pollutant reduction, and the cost of 5-m VBSs proved the lowest. The effectiveness of each BMP in reducing N/P load ranked as follows: VBS > grassed river channels (GRC) > 20% fertilizer reduction (FR20) > no-tillage (NT) > 10% fertilizer reduction (FR10). All combined BMPs had higher N and P removal efficiencies than the individual measures. We recommend combining FR20 and VBS-5m or NT and VBS-5m, which could achieve nearly 60% pollutant removal. Depending on the site conditions, the choice between FR20+VBS and NT + VBS is flexible for targeted implementation. Our findings may contribute to the effective implementation of BMPs in the Poyang Lake watershed and provide theoretical support and practical guidance for agricultural authorities to perform and direct agricultural NPS pollution prevention and control.

Spatial-Temporal Evolution of Land Use Change and Eco-Environmental Effects in the Chang-Zhu-Tan Core Area

In the past 20 years, the integration process of the Chang-Zhu-Tan region has been accelerating, and land use has undergone significant changes. Land use change is a fundamental factor causing changes in the quality of the ecological environment. It is crucial to analyze land use change in the context of rapid urbanization and its impact on the ecological environment to promote sustainable and high-quality regional development. This study takes the Chang-Zhu-Tan core area, which has the highest development and construction intensity, as the study area. Based on the Google Earth Engine (GEE) platform, the land use information is extracted using Landsat remote sensing image data and the random forest method. The remote sensing ecological index (RSEI) is constructed to analyze the ecological and environmental effects of land use change based on the spatial and temporal changes of land use types and ecological and environmental quality in the Chang-Zhu-Tan core area from 2000 to 2020. The results show that the most critical land use change in the study area from 2000 to 2020 is mainly the sharp increase in construction land, accompanied by a continuous decrease in forest and cropland. During this period, the eco-environmental quality of the study area showed a declining trend, with significant differences in spatial distribution, generally showing a distribution pattern of suburban counties outperforming central urban areas. In addition, the distribution and changes in land use and ecological environment quality coincide spatially. Different land use types have different impacts on ecological environment quality, with the conversion of forest and cropland to construction land being the main reason for the deterioration of eco-environmental quality in the study area. This study provides a basis for the coordinated development of the ecological environment and social economy in the Chang-Zhu-Tan area.

Impacts of nature reserve policy on regional ecological environment quality: A case study of Sanjiangyuan region.

Uncovering the ecological effectiveness of nature reserve policies will help protect and manage nature reserves in the future. Taking Sanjiangyuan region as an example, we examined the impacts of the spatial layout characteristics of natural reserves on the ecological environment quality by constructing the dynamic degree of land use and land cover change index, and depicted the spatial differences of the ecological effectiveness of natural reserve policies both inside and outside the natural reserves. Combined with ordinary least squares and field survey results, we explored the influencing mechanism of nature reserve policies on ecological environment quality. The results showed that the ecological quality of the whole region of Sanjiangyuan had been improved significantly since the implementation of the nature reserve policies, and that the transformation of unused land into ecological land was the most important type of land use change for the ecological environment quality improvement. The ecological effectiveness of large-scale nature reserves with concentrated and contiguous distribution was obvious, while the ecological effectiveness of small-scale nature reserves with scattered distribution and close to the administrative boundaries was relatively small. Although the ecological effectiveness of nature reserves was better than that of non-reserved areas, the ecological improvement of nature reserves and the surrounding areas was synchronous. The nature reserve policy had significantly improved ecological environment quality by implementing ecological protection and restoration projects in nature reserves. Meanwhile, it had alleviated the pressure of farmers and herdsmen's activities on the ecological environment by taking measures such as grazing restriction and guiding conversion of industry and production. In the future, we should promote the construction of ecosystem integrity protection network system with National Park as the core, strengthen the integrated protection and linkage management of National Park and surrounding areas, and help farmers and herdsmen further broaden their livelihoods.

Effects of changes in land use structure on nitrogen input in the Pingzhai Reservoir watershed, a karst mountain region

Optimizing land use composition to control nitrogen input into water bodies is one way to address surface source pollution in karst mountain regions. In this study, changes in land use, N sources, and spatial and temporal changes of N migration in the Pingzhai Reservoir watershed were evaluated from 2015 to 2021, and the relationship between land use composition and N input was elucidated. N was the main pollution in the water of the watershed; NO3− was the dominant form of N, and it did not react during migration. N came from soil, livestock manure or domestic sewage, and atmospheric deposition. Isolating the fractionation effects of source nitrogen is crucial to improve the accuracy of nitrogen and oxygen isotope traceability in the Pingzhai Reservoir. From 2015 to 2021, the grassland area in the Pingzhai Reservoir increased by 5.52%, the woodland area increased by 2.01%, the water area increased by 1.44%, the cropland decreased by 5.8%, unused land decreased by 3.18%, and construction land remained unchanged. Policies and reservoir construction were the main drivers of changes in land-use type in the catchment. Changes in land use structure affected nitrogen input patterns, with unused land having a highly significant positive correlation with inputs of NH3–N, NO2−, and TN, and construction land having a significant positive correlation with the input of NO2−. The inhibitory effect of forest and grassland on nitrogen input in the basin was offset by the promoting effect of cropland and construction land on nitrogen input, with unused land becoming a new focus area for nitrogen emissions due to a lack of environmental management. Modifying the area of different land use types in the watershed can effectively control nitrogen input to the watershed.

Arbuscular mycorrhizal fungi reduce ammonia emissions under different land-use types in agro-pastoral areas

Ammonia (NH3) emissions, the most important nitrogen (N) loss, always induce a series of environmental problems such as increased the frequency of regional haze pollution, accelerated N deposition, and N eutrophication. Arbuscular mycorrhizal (AM) fungi play key roles in N cycling. However, whether AM fungi can alleviate N losses by reducing NH3 emissions is still unclear. The potential and mechanism by which AM fungi reduce NH3 emissions in five land-use types (grazed grassland, mowed grassland, fenced grassland, artificial alfalfa grassland, and cropland) were explored in this study. The results showed that AM fungal inoculation significantly reduced NH3 emissions and the mycorrhizal responses of NH3 emissions were determined by land-use type. Structural equation modeling (SEM) showed that AM fungi and land-use type directly affected NH3 emissions. In addition, the reduction in NH3 emissions was largely driven by the decline in soil NH4+-N and pH and the increase the abundances of ammonia-oxidizing archaea (AOA) and bacteria (AOB), urease activity and plant N content induced by AM fungal inoculation and land-use type. The present results highlight that reducing the negative influence of agricultural intensification caused by land-use type changes on AM fungi should be considered to reduce N losses in agriculture and grassland ecosystems.

Ecological health risk assessment and evolution law of Ciyao River in Shanxi Province, China

ABSTRACT A comprehensive evaluation system of 25 indicators in five aspects of hydrology, water quality, morphological structure, biology and water security of typical rivers in Shanxi Province was constructed, and the evaluation criteria and methods of indicators were given. According to the characteristics of Ciyao River, 18 indicators were selected, and the weight of each indicator was determined by using the analytic hierarchy process. The ecological health status of Ciyao River was obtained through comprehensive weighted calculation. The change of land use types in the Ciyao River basin had a significant relationship with the ecological health of the Ciyao River. When the land use types were mainly farmland, forest land and grassland, water ecological health status was improved, but when land was mainly used for construction, its ecological status of the Ciyao River was weakened.

Habitat selection of wintering cranes in typical wetlands in the middle and lower reaches of the Yangtze River over the past 20 years, China

The wetlands in the middle and lower reaches of the Yangtze River are the main overwintering and perching places for cranes. To examine the habitat selection mechanism of cranes in this area, two natural wetland reserves, Shengjin Lake and Poyang Lake, which are the main habitats of typical cranes, were selected as the study area. Using 20years of Landsat satellite image data (between 1999 and 2019), the vegetation cover index was calculated from a pixel dichotomy model, and the landscape pattern index was obtained through Fragstats. The entropy method was adopted to determine the weight of the landscape index, and then, the habitat suitability index was calculated. Combined with the number of typical crane populations in the reserve, the selection mechanism of overwintering habitat of cranes was revealed. On the change of land-use type, the crane habitat of Shengjin Lake transferred more to non-crane habitat, and other land types increased, resulting in the decrease of crane habitat area. However, the change of crane habitat in Poyang Lake Reserve was small, so it can accommodate more cranes to overwintering here. In terms of vegetation coverage, most of the vegetation cover areas of Shengjin Lake were woodland near or far from the lake, but the woodland was not the habitat of cranes. Most of the vegetation-covered areas of Poyang Lake are grassland near the lake, which provide rest and foraging places for cranes. In the landscape pattern, the number of landscape patches in Shengjin Lake was large, the degree of landscape fragmentation was higher than that in Poyang Lake, the landscape complexity was higher, and the landscape diversity was simpler. This is not conducive to the maintenance of crane habitat, but also reduces the attractiveness of overwintering cranes, while the landscape suitability of crane habitat in Poyang Lake was higher than that in Shengjin Lake, and cranes were more likely to choose Poyang Lake as their overwintering habitat.

Simulation of land use trends and assessment of scale effects on ecosystem service values in the Huaihe River basin, China.

Land use demand change in the Huaihe River basin (HRB) and ecosystem service values (ESVs) in watersheds are important for the sustainable development and use of land resources. This paper takes the HRB as the research object, and using remote sensing images of land use as the data source adopts the comprehensive evaluation analysis method of ESVs based on equivalent factors and sensitivity analysis of the performance characteristics of ESV changes of different land use types. The PLUS model is used to predict spatiotemporal land use change characteristics to 2030 combining inertial development, ecological development, and cultivated land development. The spatial distribution and aggregation of ESVs at each scale were also explored by analyzing ESVs at municipal, county, and grid scales. Considering also hotspots, the contribution of land use conversion to ESVs was quantified. The results showed that (1) from 2000 to 2020, cultivated land decreased sharply to 28,344.6875 km2, while construction land increased sharply to 26,914.563 km2, and the change of other land types was small. (2) The ESVs in the HRB were 222,019 × 1012 CNY in 2000, 235,015 × 1012 CNY in 2005, 234,419 × 1012 CNY in 2010, 229,885 × 1012 CNY in 2015, and 224,759 × 1012 CNY in 2020, with an overall fluctuation, first increasing and then decreasing. (3) The ESVs were 219,977 × 1012 CNY, 218,098 × 1012 CNY, 219,757 × 1012 CNY, and 213,985 × 1012 CNY under the four simulation scenarios of inertial development, ecological development, cultivated land development, and urban development, respectively. At different scales, the high-value areas decreased, and the low-value areas increased. (4) The hot and cold spots of ESV values were relatively clustered, with the former mainly clustered in the southeast region and the latter mainly clustered in the northwest region. The sensitivity of ecological value was lower than 1, while the ESV was inelastic to the ecological coefficient, and the results were plausible. The mutual conversion of cultivated land to water contributed the most to ESVs. Based on the multi-scenario simulation of land use in the HRB by the PLUS model, we identified the spatial distribution characteristics of ESVs at different scales, which can provide a scientific basis and multiple perspectives for the optimization of land use structure and socio-economic development decisions.

Effects of land-use change and disturbance on the fine root biomass, dynamics, morphology, and related C and N fluxes to the soil of forest ecosystems at different elevations at Mt. Kilimanjaro (Tanzania)

Tropical forests are threatened by anthropogenic activities such as conversion into agricultural land, logging and fires. Land-use change and disturbance affect ecosystems not only aboveground, but also belowground including the ecosystems' carbon and nitrogen cycle. We studied the impact of different types of land-use change (intensive and traditional agroforestry, logging) and disturbance by fire on fine root biomass, dynamics, morphology, and related C and N fluxes to the soil via fine root litter across different ecosystems at different elevational zones at Mt. Kilimanjaro (Tanzania). We found a decrease in fine root biomass (80–90%), production (50%), and C and N fluxes to the soil via fine root litter (60–80%) at all elevation zones. The traditional agroforestry 'Chagga homegardens' (lower montane zone) showed enhanced fine root turnover rates, higher values of acquisitive root morphological traits, but similar stand fine root production, C and N fluxes compared to the natural forest. The decrease of C and N fluxes with forest disturbance was particularly strong at the upper montane zone (60 and 80% decrease, respectively), where several patches of Podocarpus forest had been disturbed by fire in the previous years. We conclude that changes on species composition, stand structure and land management practices resulting from land-use change and disturbance have a strong impact on the fine root system, modifying fine root biomass, production and the C and N supply to the soil from fine root litter, which strongly affects the ecosystems' C and N cycle in those East African tropical forest ecosystems.

Change rates of soil inorganic carbon vary with depth and duration after land conversion across drylands in North China

Soil inorganic carbon (SIC) accounts for 30–70% of the total soil C in global drylands. Despite the slow turnover rate, recent studies indicate that SIC could be altered by land-use change as soil organic C (SOC). Neglecting SIC change could contribute greatly to the uncertainty of soil C dynamics in drylands. However, due to the spatial-temporal variation in SIC, the direction and magnitude of SIC change (rate) induced by land-use change at a large spatial scale is understudied and poorly understood. Here, we used the space-for-time approach to test how the SIC change varied with the duration and type of land-use change and soil depth across China's drylands. We assessed the temporal and spatial variations in the SIC change rate and explored the influencing factors based on a regional dataset comprising 424 pairs of data across North China. We found that the SIC change rate of 0–200 cm after land-use change was 12.80 (5.47‒20.03) g C m−2 yr−1 (mean with 95% confidence interval), which was comparable to the SOC change rate (14.72, (5.27-24.15 g C m−2 yr−1)). Increased SIC occurred only in deep soils (>30 cm) and in the conversion from deserts to croplands or woodlands. In addition, the SIC change rate decreased with the duration of land-use change, implying that quantifying the temporal pattern of SIC change is necessary to accurately estimate SIC dynamics. The SIC change was strongly related to changes in soil water content. The SIC change rate was weakly and negatively correlated with the SOC change rate, and this relationship varied with soil depth. Together, this study highlights that to improve the prediction of soil C dynamics following land-use change in drylands, we should quantify the temporal and vertical patterns of both soil inorganic and organic C changes in the region.

Temporal and Spatial Variations in Soil Elemental Stoichiometry Coupled with Alterations in Agricultural Land Use Types in the Taihu Lake Basin

Soil elemental stoichiometry, expressed as the ratios of carbon (C), nitrogen (N), and phosphorus (P), regulates the biogeochemical processes of elements in terrestrial ecosystems. Generally, the soil C:N:P stoichiometry characteristics of agricultural ecosystems may be different from those of natural ecosystems, with distinct temporal and spatial variations along with the alterations of agricultural land use types (LUTs). The balance of soil C, N, and P reflected by their stoichiometry is primarily important to microbial activity and sustainable agricultural development. However, information on soil stoichiometric changes after long-term alterations in land use is still lacking. We characterized the temporal and spatial changes in soil elemental stoichiometry coupled with alterations in agricultural LUTs in the Taihu Lake basin. By using the ArcGIS method and meta-data analysis, our results showed that the C:N, C:P, and N:P ratios of agricultural soil in the Taihu Lake basin were much lower than the well-constrained values based on samples from forest, shrubland, and grassland at a global scale. Generally, these elemental ratios in soils increased from the 1980s to the 2000s, after experiencing changes from agricultural to other land use. The soil C:N:P stoichiometry may have maintained the increasing trend according to the meta-data analysis from the 341 peer-reviewed publications since 2010. Nevertheless, different regions showed inconsistent change patterns, with the Tianmu Mountain area surrounding the downstream of the Taihu Lake basin experiencing a reduction in those ratios. The changes in LUTs and their corresponding management practices were the major drivers shaping the spatial and temporal distributions of soil C:N, C:P, and N:P. Paddy soil generally achieved higher C sequestration potential due to more straw input and a more rapid transfer of straw C into soil C in the upstream of the Taihu Lake basin than other land use types. These results provide valuable information for the agricultural system of intensive cultivation on how their soil elemental stoichiometry characteristics vary temporally and spatially due to the alteration of agricultural land use types.