Development and protection are both vital human demands in ecologically vulnerable areas. An estimation of the land use/cover changes and their ecological responses could help to understand the ...regional ecosystem dynamics under various human demands and provide the scientific basis for managing and regulating ecosystems. In this paper, we analysed the spatial-temporal variations in land use/cover types and systematically quantified the relationships between these changes and environmental variables in the Three Gorges Reservoir area. Our results revealed that forestland coverage increased linearly to 53.48%, and that of construction land increased exponentially from 0.25% to 2.75% during 1990–2015. The land use/cover changes exhibited two distinct transformation phases: before and after impoundment. The mutual transformations among vegetation types were significant before 2000, while the forest, water and construction land coverages increased continuously by occupying cropland after 2000. The land use/cover changes were significantly correlated with environmental variables and were sensitive to three topographic variables namely, elevation, surface-height-fluctuation and slope. The vegetation dynamics were easily affected by the complex and rugged topography. Moreover, the responses of land use/cover changes varied among topographic variables. The two parameters estimated in the multiple linear regression, elevation and slope, were −0.164 and −0.268 for forestland change, −0.391 and 0.378 for water area change, and −0.068 and −0.061 for construction land change. Forest cover was so larger in the regions of higher elevation and steeper slope that afforestation occurred in the regions of moderate elevation and slope. Urbanization and impoundment mainly occurred in the regions of lower elevation, and the regions of steeper slope were more easily submerged, while urbanization mainly occurred in the regions of gentler slope. Therefore, the land use/cover changes due to ecological protection and economic development responded to the interactions among environmental variables and was targeted to different regions to reconcile the land use conflicts, providing a reference for ecosystem management in ecologically vulnerable areas.
•Land use/cover exhibited two transformation phases before and after impoundment in the study area.•Land use/cover changes were affected by environmental variables, especially topography.•Forest restoration and urbanization occurred in different regions and periods to reconcile the land use conflicts.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•The distribution of ARGs and their hosts in pig farm A/O WWTPs is revealed.•Genome bins are used to explore the ARG hosts in pig farm A/O WWTPs.•Dominant denitrifying bacteria are important ARG ...hosts in pig farm A/O WWTPs.
The anoxic-oxic (A/O) wastewater treatment process that is widely used in pig farms in China is an important repository for antibiotic resistance genes (ARGs). However, the distribution of ARGs and their hosts in the A/O process has not been well characterized. In this study, the wastewaters in the anoxic and oxic tanks for A/O processes were collected from 38 pig farms. The concentrations of 20 subtypes of ARGs, 5 denitrification-related genes, 2 integrons, and bacterial community composition were investigated. Bacterial genome binning was performed using metagenome sequencing. In this study, 20 subtypes of ARGs and integrons were detected in all sampling sites. A total of 16 of the 20 subtypes of ARGs were detected with the highest abundance in anoxic tanks, and sul1 was detected with a maximum average abundance of 19.21 ± 0.24 log10 (copies/mL). Cooccurrence patterns were observed for some genes in the pig farm A/O process, such as sul1 and intl1, sul1 and tetG, and tetO and tetW. There was a significant cooccurrence pattern between the dominant denitrifying bacteria and some ARGs (blaTEM, ermB, tetC, tetH and tetQ), so the dominant denitrifying bacteria were considered to be potential ARG hosts. In addition, 170 highly abundant bacterial genome bins were assembled and further confirmed that the denitrifying bacteria Brachymonas, Candidatus Competibacter, Thiobacillus and Steroidobacter were the important ARG hosts in the pig farm A/O process, providing a useful reference for the surveillance and risk management of ARGs in pig farm wastewater.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Vegetation restoration on degraded lands has been encouraged worldwide due to its ecological services and function of controlling soil erosion and improving carbon (C) stocks in terrestrial ...ecosystems. Although the processes of runoff and sediment detachment and transport are well recognized, the effects of vegetation restoration on organic C loss through soil erosion are not fully understood within a given landscape. This study conducted a synthesis from 66 sites to evaluate the effects of vegetation restoration on annual C loss induced by soil erosion across the key areas of the ‘Grain for Green’ Program (GGP) in the Loess Plateau, China. The results showed that vegetation restoration has significantly reduced the annual C loss in sediment and from runoff. Since 2000, a total of 8.6 × 106 ha degraded land has been converted to forests, shrubs and grasslands under the GGP, which has reduced runoff by 1.5 × 109 m3 and is associated with 7.3 × 103 Mg C; furthermore, lost sediment has reduced by 348.7 Tg, which is associated with 1.8 Tg C per year, across the Loess Plateau. In the zone with a mean annual precipitation (MAP) < 550 mm, the degraded lands that have been converted to grasslands and shrubs have reduced more soil and water losses than have the lands that have been converted to forests; additionally, in the zone with a MAP >550 mm, the degraded lands that have been converted to forests have less soil erosion than do the lands that have been converted to grasslands and shrubs. Moreover, C loss induced by soil erosion was mainly affected by plant cover, soil porosity, slope, land-use change, and rainfall intensity on the Loess Plateau. This study suggests that optimal vegetation restoration measures should be adopted based on local conditions to reduce C loss induced by soil erosion.
•Vegetation restoration significantly reduced C loss in annual runoff and sediment.•Vegetation restoration driven by land-use changes could reduce the soil erosion.•Soil, topography, land uses and rainfall intensity affecting soil erosion induced C loss.•Optimal vegetation restoration measures should be adopted based on local conditions.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•More intensive land use activities during 2010–2018 was observed in UAMRYR.•Ecological functions exacerbated due to the built-up land expansion.•ESV decreased from $238.86 billion in 2000 to $234.28 ...billion in 2018.•Ecological protection should be strengthen in high altitudes of natural vegetation.
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.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Habitat quality is an important indicator for assessing biodiversity and is critical to ecosystem processes. With urban development and construction in developing countries, habitat quality is ...increasingly influenced by landscape pattern changes. This has made habitat conservation to be an increasingly urgent issue. Despite the growing interest in this issue, studies that reveal the role of land use change in habitat degradation at multiple scales are still lacking. Therefore, we analyzed the spatial and temporal variations of habitat quality of the Three Gorges Reservoir area by the InVEST habitat quality model and demonstrated the responses of habitat quality to various landscape dynamics by correspondence analysis. The result showed that the habitat quality score of this area increased from 0.685 in 2000 to 0.739 in 2015 and presented a significant spatial heterogeneity. Habitat quality was significantly higher in the northeastern and southwestern parts of the reservoir area than in other regions. Meanwhile, habitat quality improved with altitude and slope, and increased for all altitude and slope zones. The habitat quality of >1000 m and >25° zone exceeds 0.8, while the habitat quality of <500 m and <15° zone is less than 0.6. Habitat quality significantly varied among landscape dynamics and was extremely sensitive to vegetation recovery and urban expansion. The vegetation restoration model of returning farmland to forest is difficult to sustain, so we suggest changing the vegetation recovery model to constructing complex vegetation community. This study helps us to better understand the effects of landscape pattern changes on habitat quality and can provide a scientific basis for formulating regional ecological conservation policies and sustainable use of land resources.
•A analytical framework is established based on three trade-off types for ecosystem services.•Three trade-off types for ecosystem services are evaluated.•Zones of land use management based on three ...trade-off types of ES are defined.•The reasons and interactions of the three trade-off types for ecosystem services are discussed.
The trade-offs of ecosystem services (ES) are at the frontier of geographical and ecological studies. However, previous studies have focused on either supply-supply trade-off or supply–demand trade-off, while the integrated research of three trade-off types for ES (i.e. supply-supply trade-off, demand-demand trade-off, and supply–demand trade-off) needs to be further studied. This study integrated three trade-off types for ES to establish an analytical framework. This framework was then applied to a sub-watershed of the Yellow River in China (i.e., the Fenghe River watershed). Based on a quantitative assessment of both the supply and demand of ES, this study quantifies and displays these three trade-off types for ES in this sub-watershed. From the supply perspective, obvious trade-offs exist between food provision as well as water yield, carbon sequestration, and soil retention. From the demand perspective, there are weak conflicts between environmental experts and other stakeholders, and obvious trade-offs exist between soil retention as well as food provision, water yield, carbon sequestration, and eco-recreation. From the supply–demand match perspective, a deficit for food provision, water yield, and carbon sequestration exists in the northern urban areas, while a surplus exists in the southern areas. No deficit was found for soil retention and eco-recreation at the sub-watershed scale. Based on the spatial characteristics of these three trade-off types for ES, the Fenghe River watershed could be divided into 10 land use management zones. Finally, the corresponding measures and polices are proposed to optimize the matching of ES supply–demand. This study contributes to the optimization of the sustainability of ES from a novel perspective, and provides a scientific basis for land use management.
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Land use change is an important way for human activities to affect ecosystems. Based on the land use demands and policies, the simulation of future land use changes under different scenarios can test ...the rationality of socio-economic and policy-oriented land use changes. In this study, we set three scenarios of regular growth, ecological protection, and ecotourism development in 2030 for the Beibu Gulf area, China. We simulated the spatial distribution and evolution characteristics of the future landscape pattern using the Scenario Generator Rule Based Module of InVEST. Meanwhile, the ecosystem service value (ESV) was estimated by the improved unit area value equivalent method to reveal the trend of ESVs under different regional development models. The results indicated that the land use changes in the Beibu Gulf during 1999–2014 showed significant spatial heterogeneity. The farmland was mainly distributed in Beihai, the forestland was located in Fangchenggang, while the orchard was concentrated on Qinzhou. Due to economic construction and urban expansion, construction land and aquaculture land were gradually growing, while farmland and mud flat continued to decrease. Between 2014 and 2030, the total ESV decreased in the regular growth scenario and gradually increased in the ecological protection scenario and ecotourism development scenario. In addition, by comparing the three scenarios, the ecotourism development scenario is a more reasonable model for Guangxi Beibu Gulf area, which realized the trade-off between tourism development and resource conservation. Therefore, regional planners should not only consider maximizing ESVs when planning for ecosystem services, but also strive to maintain a reasonable structure of ecosystem services. Some suggestions were provided in this paper at the macro level and the local development model level respectively, which offered some references for the rational allocation of land resources, ecological environmental protection and ecotourism development in the coastal area of Beibu Gulf.
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•Decoupling the effects of climate change and LUCC on soil loss through scenario design.•Overall effect of all LUCC potentially improved soil retention service.•Impact of climate change on soil loss ...was difficult to be offset by the positive effect of LUCC.•Afforestation offset the potential soil loss caused by urbanization and economic construction.•LUCC and their effects on soil loss change exhibited distinct spatial variances.
Climate, land use and land cover (LULC) changes are among the primary driving forces of soil loss. Decoupling their effects can help in understanding the magnitude and trend of soil loss in response to human activities and ecosystem management. Here, the RUSLE model was applied to estimate the spatial-temporal variations of soil loss rate in the Three Gorges Reservoir (TGR) area during 2001–2015, followed by a scenario design to decouple the effects of climate and LULC changes. The results showed that increasing rainfall generated as much as 2.90 × 107 t soil loss in the TGR area. However, such effect was offset by changes in LULC particularly afforestation, which retained about 1.10 × 107 t soil annually. Other human activities such as dam development and urbanization aggravated soil loss by as much as 1.40 × 106 t annually. Because of land use policies that favor economic development, distinct spatial variances of soil loss were observed in TGR area. Soil loss in some counties located downstream of the TGR area (i.e., close to the dam) was more influenced by dam development, but soil loss in the other counties was more influenced by urbanization. As climate change (i.e., increasing rainfall) did not affect plant performance in TGR area, our findings suggested that ecological restoration was more beneficial to curb the amount of soil loss caused by urbanization and dam construction.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•Forest restoration programmes in China have targeted ecosystem services and livelihoods.•Forest restoration programmes have improved key ecosystem service indicators.•The key ecosystem services of ...the persisting forest are irreplaceable.•Forest restoration programmes have not had a negative impact on livelihood.•The inequalities of livelihoods among households may lead to a resurgence of deforestation.
China has made tremendous efforts in forest restoration (FR), and has established ambitions to govern its fragile ecosystem and improve green welfare until 2035. However, debate still exists over whether FR can simultaneously improve ecosystem services and enhance livelihoods. In this paper, we test the impacts of forest restoration on key ecosystem services and livelihoods via a case study of Badong County in the TGRA, China. The Revised Universal Soil Loss Equation and Carnegie-Ames-Stanford Approach were used to evaluate the soil erosion rate (SER) and net primary productivity (NPP), and we analyzed livelihoods through 520 surveys. Our results revealed that forestland increased significantly from 45.34% to 69.63% during 1990–2015. The annual average SER significantly dropped from 67.01 to 51.18 t·ha−1·yr−1 during 2001–2015, and the annual average NPP increased from 547.12 gC·m−2·a−1 in 2000 to 609.81 gC·m−2·a−1 in 2015. However, the afforestation area offered disadvantages when compared with the persisting forest area in SER and NPP. Households in ecologically fragile areas have equal opportunities in, among others, infrastructure and government policies, but their income and living conditions are often heterogeneous. The per capita income and area of residence improved under FR. Nonetheless, the inequality in per capita income between participating households (PHs) and nonparticipating households (NPHs) increased. Compared with NPHs, PHs lost more cropland, and agricultural income, and more PH householders were forced to find new livelihood activities. These inequalities are not conducive to the sustainable development of FR. Accordingly, we recommend that restoration efforts should focus on forest quality and habitat availability improvement in the persisting forest area and afforestation area, and on new reforestation programmes where appropriate. The government should provide sustainable and science-based ecological subsidies and help PHs obtain alternative livelihood activities, which contribute to higher household income and poverty alleviation.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The urbanization process can alter the structure of urban land use and result in variations in urban ecosystem services (ESs). Researching the driving mechanism of multi-level indicators of ...urbanization on the supply and demand of ESs can enhance our understanding of the ecological and environmental impacts of urbanization. This study investigates the driving mechanisms underlying the relationship between urbanization and the supply–demand dynamics of ecosystem services (ESs) in the Yangtze River Middle Reaches Urban Agglomeration (YRMRUA). First, we assessed the variation in the key ESs (food production, carbon storage, and culture service) from 2000 to 2019 at both city and provincial levels. Second, ES demand and the supply–demand index (SDI) were calculated utilizing socioeconomic indicators. The Geographical Detector model was applied to analyze the individual and combined effects of urbanization on the supply and SDI of ESs. The results showed that an increase in areas of supply and demand was unbalanced in the YRMRUA from 2000 to 2019, with a predominant concentration observed in the provincial capital cities. Scale urbanization exhibits the most substantial influence on the SDI, with a q-value of 0.6, while land urbanization exerts the most pronounced effect on ES supply, with a q-value of 0.7. Furthermore, it is noteworthy that the combined effect of urbanization on ESs surpasses the individual effect, with q-values exceeding 0.5. The interaction between scale urbanization and other indicators has the greatest impact on the SDI of carbon storage. Population and economic urbanization exhibit a more substantial impact on food production and cultural service compared to other primary indicators. Simultaneously, the joint effects of secondary indicators between per capita living area and per capita road area have a greater impact on ES supply than other secondary indicators. These findings illustrate that urbanization indicators are not independent of each other, but have a combined effect. Furthermore, the urbanization process in the YRMRUA has exhibited a gradual deceleration, leading to a diminishing influence on ESs. This study can contribute to the comprehension of urbanization and ESs when dealing with the conflict between urban development and ecological sustainability.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
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