CN 11-5366/S     ISSN 1673-1530
“风景园林,不只是一本期刊。”

拉萨市中心城区生态服务价值与人类活动时空耦合分析

Spatio-temporal Coupling of Ecological Service Value and Human Activity Intensity in the Central Urban Area of Lhasa City

  • 摘要:
    目的 高海拔城市生态系统对人为干扰具有特殊敏感性,其生态服务价值(ecosystem service value, ESV)与人类活动强度(human activity intensity, HAI)的耦合规律尚未明晰。揭示拉萨市中心城区ESV与HAI的时空交互特征,阐明快速城市化进程中ESV的响应阈值,可为高海拔城市生态安全格局优化提供定量依据。
    方法 基于2007—2022年土地利用遥感影像数据,在0.5 km×0.5 km格网尺度下运用生态系统服务价值评估模型、生态服务价值流向损益模型、人类活动强度指数评估模型和双变量局部空间自相关分析法,探讨拉萨市中心城区ESV的时空变化特征及其与HAI的关联性。
    结果 1)2007—2022年拉萨市耕地和绿地小幅减少,城市建设用地大幅增加,土地类型转换以由耕地和草地转为城市建设用地为主;2)2007—2022年拉萨市中心城区ESV呈下降趋势,共减少4628万元,在空间分布上,植被覆盖是影响区域空间分异的关键因素,拉萨河流域和拉鲁湿地附近ESV最高,向中心城区方向逐渐减弱;3)人类活动强度高影响区集中在拉萨市老城区,并向外扩展形成东、西翼延伸态势;低影响区域则位于中心城区南部;4)ESV与HAI的空间关联性呈现衰减趋势,全局莫兰指数从2007年的0.249 197下降至2022年的0.083 119,局部聚集类型以低ESV-高HAI和高ESV-高HAI聚集为主。
    结论 揭示高海拔城市存在人类活动强度阈值,可通过生态修复手段可逆转局部生态系统退化,但城市扩张会加剧生态冲突。建议划定生态红线并实施差异化管控,支撑高海拔城市可持续发展。

     

    Abstract:
    Objective This study investigates the spatio-temporal dynamics of ecosystem services (ES) in Lhasa, a high-altitude city on the Tibetan Plateau, where fragile ecosystems face escalating pressures from urbanization. Ecosystem services, defined as benefits provided by natural ecosystems to sustain human well-being and ecological balance, are critical for biodiversity conservation and socio-economic development. While ES valuation (ESV) has been widely studied in low-altitude regions, research on high-altitude ecosystems remains limited despite their heightened vulnerability due to unique geographic and climatic conditions. The study aims to: 1) quantify urbanization impacts on ESV from 2007 to 2022; 2) evaluate the effectiveness of ecological restoration initiatives such as the Lhasa River Comprehensive Governance Project; 3) identify spatial thresholds in the ESV-human activity intensity (HAI) relationship to inform sustainable urban planning.
    Methods A high-resolution spatial analysis framework (0.5 km × 0.5 km grid) was applied to assess ESV and HAI dynamics over 15 years (2007–2022). ESV was calculated using a dynamic model based on the improved equivalence factor method developed by Xie Gaodi and colleagues in 2015, integrating net primary productivity (NPP), precipitation, land cover, vegetation type, and environmental productivity. HAI was quantified through a composite index reflecting land-use change, population density, transportation infrastructure, and industrial development, with weights assigned based on ecological impacts. Spatial autocorrelation (Moran’s I ) and local cluster analysis were employed to identify interactions between ESV and HAI, accounting for the Tibetan Plateau’s topography.
    Results The results of the study highlight significant spatio-temporal variations in ESV and human activity intensity in Lhasa. From 2007 to 2022, the total ESV decreased by 24.3%, amounting to a loss of 462.8 million CNY, with a brief recovery observed between 2012 and 2017. This recovery was largely driven by the Lhasa River Comprehensive Governance Project, which focused on wetland restoration and the improvement of hydrological services. The analysis of spatial patterns indicated that areas with high ESV values were predominantly concentrated around the Lhasa River Basin and the Lalu Wetland, while areas with low ESV values exhibited expansion in newly urbanized zones. A bivariate spatial autocorrelation analysis indicated that the positive spatial correlation between ESV and HAI weakened over the study period, with Moran's I decreasing from 0.249 in 2007 to 0.083 in 2022. Local cluster analysis further identified shifts in spatial patterns, with a 38.6% reduction in high-high clusters (areas with both high ESV and low HAI) and a 217% expansion in low-high clusters (areas with low ESV and high HAI), predominantly in newly urbanized areas. Moreover, the study identified a significant negative correlation(p < 0.05) between ESV and HAI in 23.5% of the grid cells by 2022, indicating a decoupling of the relationship between human activity and ecosystem service provision. The research identifies a threshold effect in the ESV − HAI relationship, where the decline in ESV accelerates when HAI exceeds a value of 0.65, with a regression coefficient of −1.32 and a p-value of less than 0.001. This threshold suggests that beyond a certain level of HAI, the negative impact on ecosystem services becomes more pronounced. between ESV and HAI in 23.5% of the grid cells by 2022, indicating a decoupling of the relationship between human activity and ecosystem service provision. The study identified a threshold effect in the ESV-HAI relationship, where the decline in ESV accelerated when HAI exceeded a value of 0.65, with a regression coefficient of −1.32 and a p-value of less than 0.001. This threshold suggests that beyond a certain level of human activity intensity, the negative impact on ecosystem services becomes more pronounced.
    Conclusion From 2007 to 2022, Lhasa’s central urban area experienced significant land-use shifts, marked by cropland and grassland conversion to urban construction land. Ecosystem service value (ESV) initially decreased before a partial recovery, with an overall decline of 46.28 million CNY. Water bodies and wetlands contributed most to ESV, while low-value zones expanded in rapidly urbanizing areas. Human activity intensity (HAI) intensified radially, concentrating in older urban cores and expanding post-2012.Study limitations include sensitivity of valuation methods and data resolution constraints. Future work should integrate high-resolution models and climate scenarios to refine ESV-HAI interactions. Policy priorities include enforcing ecological redlines, protecting critical wetlands, and balancing urban growth with ecological resilience.

     

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