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- Central Asia; Tarim River; shelterbelt; Tugai; desertification; sustainability; afforestation; ecosystem services; ecological engineering (1)
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Urban green space (UGS) is crucial to the healthy development of urban residents. However, UGS that is accessible can benefit residents to an even greater degree. Based on the two-step floating catchment area model (2SFCA) and the location quotient (LQ), we analyzed the changes from 1999 to 2019 in UGS walking accessibility and equity in built-up areas of Urumqi at different administrative levels, and how UGS policy affects the improvement of accessibility. The results showed that UGS accessibility and equity are not evenly distributed at different administrative levels and UGS categories. Although the overall UGS accessibility and equity has improved with policy implementation, these changes are caused by metro-level UGS construction in urban fringe areas. The improvement in UGS accessibility at the neighborhood level in densely populated areas is neglected, which leads to a mismatch between UGS construction and population distribution. In addition, the accessibility of UGS is also limited by geographical location, population density, road distribution, and water shortage in arid metropolitan Urumqi. Our research results provide a theoretical basis for Urumqi and other cities in the optimization of UGS structure and the realization of social equity.
Multi-scenario dynamic prediction of ecological risk assessment in an arid area of northwest China
(2023)
Ecological security is essential for the development of environmental health and human society. However, the driving mechanisms and spatial non-stationarity of ecological risks are still unknown, particularly in arid areas. Thus, this study constructed an ecological risk index (ERI) research framework in arid areas based on land use and socio-economic data from 1980 to 2020 to investigate the spatiotemporal evolution trend, driving mechanisms, and spatial non-stationarity of ecological risk and predict the ecological risk under business-as-usual, economic development, and ecological protection scenarios using a patch-generating land use simulation (PLUS) model. The results show that: (1) cropland and build-up land were expanding, whereas forestland and grassland water bodies were shrinking. Compared with the two development stages from 1980 to 2000 and from 2000 to 2020, cropland increased by 4.73% and 51.52%, respectively, whereas build-up land increased by 12.64% and 106.52%, respectively, indicating rapid development and drastic changes in the past 20 years. (2) With the change in landscape diversity, the regional ecological risks showed an increasing trend, whereas the future ecological risks showed an increasing trend because of the cumulative effect of landscape pattern changes caused by human activities. (3) Moreover, dramatic changes in ecological risk, particularly in areas of intense human activity in build-up land, agricultural land, artificial oases, and mountainous areas. Corresponding to the analysis of driving mechanisms, population, GDP, distance to government, water, and primary roads; have a significant effect on ecological risk, whereas DEM has direct and indirect effect paths. Ultimately, the proposed analysis framework can present the spatiotemporal changes of ecological risks and their influencing mechanisms, which can help develop sustainable development policies.
Cities at the fringe of the Taklimakan desert in NW China are prone to dust and sand storms with serious consequences for human well-being. The Kökyar Protection Forest was established in the 1980s as an ecological engineering project with the intent of protecting the city of Aksu, NW China, from these impacts. It is designed as a combination of poplar shelterbelts and orchards, irrigated by river water from the Aksu River, the main tributary of the Tarim River. Prevalent literature describes it as an afforestation project for combatting desertification with manifold positive effects for the economic, social, and environmental dimension of sustainable development. This paper sets out to challenge these claims by a sustainability assessment in which the plantation is examined from a broader perspective, embedding it to the wider context of social and environmental problems in South Xinjiang. Methods comprise evapotranspiration calculations, interviews, a socioeconomic household survey, stakeholder dialogues, and literature research. Results affirm its economic sustainability, but see a mixed record for the social sphere. From the nature conservation point of view, it has to be classified as unsustainable because its high irrigation water consumption results in the downstream desiccation and desertification of natural riparian forests along the Tarim River, causing a forest loss in the downstream area twice the size of the forest gain in the upstream area. There is a trade-off between artificial shelterbelt plantations for urban ecosystem services on the one hand side, and natural riparian forests and their biodiversity on the other hand side. The paper recommends restricting agricultural extension, and using locally adapted less water consuming agroforestry schemes to protect urban dwellers from dust stress.
Understanding the balance between supply and demand of ecosystem services (ESs) is helpful for sustainable urban management. However, the interactions among multiple ESs supplies and demands remain under-researched, and ESs supply and demand spatial heterogeneity and correlation characteristics at the city level are rarely studied, especially in arid areas. To fill this gap, we established a comprehensive assessment framework of ESs supply and demand through integrating multi-source remote sensing data, social economy, and policy objectives, for the oasis city of Urumqi, China. The ESs supply–demand mismatches were revealed at the city level, and the spatial relationship between the ESs supply and demand was analyzed using spatial statistics. The results demonstrated that: (1) The total quantity of supply and demand of food provision, carbon sequestration, PM10 removal, and recreation services in Urumqi revealed that the demand was greater than the supply, the deficits being 16.10 × 107 kcal/ha, 6.88 × 104 t/ha, 155.86 kg/ha, and 697.26, respectively. (2) The supply and demand assessment of ESs revealed spatial differences from the city center to the suburbs, which further indicated that there are neighborhood similarities between the supply and demand of ESs. (3) The matching types of ESs supply and demand present obvious spatial heterogeneity, which can be divided into four types: High–high, high–low, low–high, and low–low. Owing to rapid urban development in the inner city, the city center is dominated by low–high, whereas the urban–rural ecotone is characterized by high–low, owing to the higher elevation and water resource advantages in the suburbs. Based on the analysis of the supply, demand, and matching of ESs, economic development and sustainable management policies are proposed for different ecological spaces. Integr Environ Assess Manag 2021;17:1293–1304. © 2021 SETAC
Trunk internal decay is a common phenomenon in forest ecosystems, causing the loss of forest resources. Euphrates poplar (Populus euphratica Oliv.) is the only constructive tree species of the desert riparian forests along the Tarim River in northwestern China. The ecosystem stability of these forests has been damaged due to widespread internal decay or hollow rot in many tree trunks. However, forest resource conservation is difficult due to the unclear spatial patterns of P. euphratica trunk decay under different water conditions and tree morphology in the middle (MTR) and lower reaches (LTR) of the Tarim River. We conducted a field experiment and lab analysis to assess the reliability of the ARBOTOM® 2D stress wave Non-Destructive Testing (NDT) technique on P. euphratica populations. We explored the quantitative characterization method and the spatial distribution patterns of P. euphratica trunk internal decay in the MTR and LTR. Our study found that (1) the accuracy of the stress wave NDT technique in detecting trunk decay of P. euphratica in the arid desert area was more than 80%; The severity of internal trunk decays can be quantitatively characterized by the combination of the Matlab Image Processing Toolbox, (2) the trunk decay proportion of P. euphratica showed an increasing trend with the tree height in the MTR. The LTR first increased, then decreased. The degree of decay was highest when the tree height was 6–7 m. The trunk decay proportion of individual trees positively correlated with the diameter at breast height and crown loss (p < 0.001) and negatively correlated with the crown diameter (p < 0.001). The higher the decay occurrence, the worse the individual size was, and vice versa, and (3) the decay proportion of the P. euphratica showed an overall increasing trend with an increase in groundwater depth. The trunk decay was significantly higher in the LTR compared to the MTR at the same distance of 300–1050 m from the river channel. Our findings suggested that the trunk decay in P. euphratica had a higher difference among different tree morphology, and the occurrence of decay in the LTR was much higher than in the MTR. The water stress at the site is one of the leading factors in internal defects in the riparian forests along the Tarim River. The results provide a theoretical basis and scientific support for desert riparian forest ecosystems’ conservation and sustainable management.
Rapid urbanization has negative effects on ecosystem structure, function, and balance, leading to the loss of ecosystem services (ES) and posing a threat to regional sustainable development. However, the complex interactive coercing relationship between urbanization and ES is not yet fully understood, especially in arid Northwestern China. In this study, we constructed an evaluative framework for urbanization and ES using land cover/land use data and socioeconomic data from 1990 to 2018. We used global and local autocorrelation models to reveal the spatiotemporal interaction between urbanization and ES. The results revealed that the urbanization index increased from 0.06 in 1990 to 0.16 in 2018 in Xinjiang, and urbanization was significantly negatively correlated with ES. With the acceleration of urbanization, the ecosystem services value (ESV) has decreased 2,698.74 × 109 Yuan from 1990 to 2018 (6.62 Yuan = 1 .00 US$). Due to geographical advantages, resource conditions, and land use changes, the spatial relationship of urbanization and ES has obvious heterogeneity. High–low correlation areas are mainly concentrated in the Northern Tianshan Mountain Economic Zone, whereas low–high correlation areas are concentrated in the Kashgar and Hotan Oases in southern Xinjiang. Based on regional geographical conditions and the spatial heterogeneity of resources, diversified ecological, social, and economic balance models should be considered to promote future sustainable urban planning and development.
Policy recommendations
(2021)