Currently, urban areas are the largest segment of the world’s population, and they can reach up to 80% of it in some countries. Understanding green areas is of paramount importance to also understand the population’...Currently, urban areas are the largest segment of the world’s population, and they can reach up to 80% of it in some countries. Understanding green areas is of paramount importance to also understand the population’s mental health and well-being, as well as to achieve ecological understanding and its impact on urban infrastructure. Thus, the aim of the present study is to carry out a survey on both urban afforestation structure and on its social impact on a Brazilian municipality. It also sought to understand the damages caused by these species to urban infrastructure in comparison to data collected in 2009, to assess forest coverage in this municipality and tree planting underutilized capacity. Accordingly, all the streets in this municipality’s urban area, the botanical data of each tree and its damage to the city’s infrastructure and phytosanitary conditions were surveyed (from 1 to 5). Data were compared to those from the 2009 census, and social issues were analyzed. In total, 5044 individuals belonging to 189 species were recorded. The most often found species were Lagerstroemia indica and Murraya paniculata. Out of the total number of trees, 458 trees scored at least one score “5” in one of the criteria, and this number represents 8.9% of the total of the trees. L. indica was the species accounting for the highest rates of phytosanitary and infrastructure issues. Data comparison evidenced that urban tree canopy lost 25% of its vegetation between the two measurements taken herein, but the number of species has increased. When it comes to damages, many trees started showing phytosanitary issues or damage to urban infrastructure.展开更多
In recent decades, Urban Heat Island Effects have become more pronounced and more widely examined. Despite great technological advances, our current societies still experience great spatial disparity in urban forest a...In recent decades, Urban Heat Island Effects have become more pronounced and more widely examined. Despite great technological advances, our current societies still experience great spatial disparity in urban forest access. Urban Heat Island Effects are measurable phenomenon that are being experienced by the world’s most urbanized areas, including increased summer high temperatures and lower evapotranspiration from having impervious surfaces instead of vegetation and trees. Tree canopy cover is our natural mitigation tool that absorbs sunlight for photosynthesis, protects humans from incoming radiation, and releases cooling moisture into the air. Unfortunately, urban areas typically have low levels of vegetation. Vulnerable urban communities are lower-income areas of inner cities with less access to heat protection like air conditioners. This study uses mean evapotranspiration levels to assess the variability of urban heat island effects across the state of Tennessee. Results show that increased developed land surface cover in Tennessee creates measurable changes in atmospheric evapotranspiration. As a result, the mean evapotranspiration levels in areas with less tree vegetation are significantly lower than the surrounding forested areas. Central areas of urban cities in Tennessee had lower mean evapotranspiration recordings than surrounding areas with less development. This work demonstrates the need for increased tree canopy coverage.展开更多
【目的】城市公园树木的碳(C)计量和管理是城市减少CO2排放的有效策略之一,树木冠层覆盖(Urban tree canopy,UTC)信息在树木生物量和C储存量的计量中具有一定潜力,旨在初步估算广州市典型城市公园基于UTC和叶面积的碳存储和碳固定量的...【目的】城市公园树木的碳(C)计量和管理是城市减少CO2排放的有效策略之一,树木冠层覆盖(Urban tree canopy,UTC)信息在树木生物量和C储存量的计量中具有一定潜力,旨在初步估算广州市典型城市公园基于UTC和叶面积的碳存储和碳固定量的转换系数及适用性。【方法】基于城市树木碳输入生态过程,对城市绿地系统树木冠层覆盖与其C存储和C固定功能的计量方法进行探索,建立了基于广州城市公园树木冠层覆盖和叶面积参数指标的C存储和C固定转换系数,依此估算广州市4个典型城市公园C存储和C固定量。【结果】广州市城市公园基于UTC的C存储转换系数为92.215±12.836 t·hm-2,C固定量转换系数为5.606±2.19 t·hm-2a-1;基于叶面积总量的C存储转换系数为24.17±7.12 t·hm-2,C固定量转换系数为2.59±0.5 t·hm-2a-1。基于叶面积总量转换系数估算的C存储量和C固定量比基于面积尺度转换系数估算的分别要小0.4%和3.3%,比基于UTC面积估算的碳存储量高13.8%,而碳固定量要低3.15%。【结论】基于UTC的C存储和C固定量的计量方法仅对城市树木覆盖区域进行估算,完全剔除了城市公园中其他复杂的下垫面类型,该计量方法其结果相对精准。基于树木叶面积的C存储和C固定量估算既考虑了树木冠层覆盖的面积,也考虑了冠层结构指标(叶面积指数),充分考虑了植物C输入过程的各个影响因素,其计量结果相对较低,但具有更高的精度。展开更多
城市林木树冠覆盖(urban tree canopy,UTC)既是衡量一个城市生态状况的标志性指标,也是衡量森林城市建设成就的关键指标,其中的潜在林木树冠覆盖(possible urban tree canopy,简称PUTC)又与城市森林建设目标的科学制定息息相关。在国外...城市林木树冠覆盖(urban tree canopy,UTC)既是衡量一个城市生态状况的标志性指标,也是衡量森林城市建设成就的关键指标,其中的潜在林木树冠覆盖(possible urban tree canopy,简称PUTC)又与城市森林建设目标的科学制定息息相关。在国外文献与实践案例研究的基础上,以北京市六环外1km以内范围为研究对象,利用2002和2013年的0.5m分辨率航、卫片影像,通过其解译的地表覆盖数据,对其两个年度的潜在林木树冠覆盖的区域分布和动态变化进行分析,并利用人口密度、道路密度和现实林木树冠覆盖率等指标,以村(社区)为单元对其潜在林木树冠覆盖的优先度进行了分析评价。结果显示,11年间,研究区域的PUTC从40882.18hm^2减少到了18845.82hm^2,空间分布也呈现出沿环路越是靠近城市中心区域,其分布也越少的格局,从其类型上看,随着时间的推移,其类型的丰富度也越来越低,到2013年,则呈现出荒草地类型绝对占优的格局。PUTC的斑块数量从109892个减少为7793个,但斑块平均面积从2002年的0.37hm^2增加到了2013年的2.36hm^2,斑块大小格局也从2002年的小斑块占绝对优势演变为各种类型"平分秋色"的状况。以PUTC为核心的村(社区)区域潜力评价结果显示,整个研究区域在2002年时低潜力和中潜力区域范围最大,分别占到了研究区域的32.39%和28.83%,2013年时潜力格局改变为极低潜力和低潜力区域面积最大,分别占研究区域总面积的25.83%和50.94%。极高优先度和高优先度区域应该是北京城市未来重点发展城市森林的区域,目前的潜在优先度评价结果表明,其面积占比分别达到了研究区域面积的13.11%和41.79%,其中极高优先度区域主要分布在构成城市核心区的东城区和西城区,因此北京城区未来的林木树冠发展策略应该走植被潜在斑块与不透水地表潜在斑块共同开发之路。展开更多
文摘Currently, urban areas are the largest segment of the world’s population, and they can reach up to 80% of it in some countries. Understanding green areas is of paramount importance to also understand the population’s mental health and well-being, as well as to achieve ecological understanding and its impact on urban infrastructure. Thus, the aim of the present study is to carry out a survey on both urban afforestation structure and on its social impact on a Brazilian municipality. It also sought to understand the damages caused by these species to urban infrastructure in comparison to data collected in 2009, to assess forest coverage in this municipality and tree planting underutilized capacity. Accordingly, all the streets in this municipality’s urban area, the botanical data of each tree and its damage to the city’s infrastructure and phytosanitary conditions were surveyed (from 1 to 5). Data were compared to those from the 2009 census, and social issues were analyzed. In total, 5044 individuals belonging to 189 species were recorded. The most often found species were Lagerstroemia indica and Murraya paniculata. Out of the total number of trees, 458 trees scored at least one score “5” in one of the criteria, and this number represents 8.9% of the total of the trees. L. indica was the species accounting for the highest rates of phytosanitary and infrastructure issues. Data comparison evidenced that urban tree canopy lost 25% of its vegetation between the two measurements taken herein, but the number of species has increased. When it comes to damages, many trees started showing phytosanitary issues or damage to urban infrastructure.
文摘In recent decades, Urban Heat Island Effects have become more pronounced and more widely examined. Despite great technological advances, our current societies still experience great spatial disparity in urban forest access. Urban Heat Island Effects are measurable phenomenon that are being experienced by the world’s most urbanized areas, including increased summer high temperatures and lower evapotranspiration from having impervious surfaces instead of vegetation and trees. Tree canopy cover is our natural mitigation tool that absorbs sunlight for photosynthesis, protects humans from incoming radiation, and releases cooling moisture into the air. Unfortunately, urban areas typically have low levels of vegetation. Vulnerable urban communities are lower-income areas of inner cities with less access to heat protection like air conditioners. This study uses mean evapotranspiration levels to assess the variability of urban heat island effects across the state of Tennessee. Results show that increased developed land surface cover in Tennessee creates measurable changes in atmospheric evapotranspiration. As a result, the mean evapotranspiration levels in areas with less tree vegetation are significantly lower than the surrounding forested areas. Central areas of urban cities in Tennessee had lower mean evapotranspiration recordings than surrounding areas with less development. This work demonstrates the need for increased tree canopy coverage.
文摘城市林木树冠覆盖(urban tree canopy,UTC)既是衡量一个城市生态状况的标志性指标,也是衡量森林城市建设成就的关键指标,其中的潜在林木树冠覆盖(possible urban tree canopy,简称PUTC)又与城市森林建设目标的科学制定息息相关。在国外文献与实践案例研究的基础上,以北京市六环外1km以内范围为研究对象,利用2002和2013年的0.5m分辨率航、卫片影像,通过其解译的地表覆盖数据,对其两个年度的潜在林木树冠覆盖的区域分布和动态变化进行分析,并利用人口密度、道路密度和现实林木树冠覆盖率等指标,以村(社区)为单元对其潜在林木树冠覆盖的优先度进行了分析评价。结果显示,11年间,研究区域的PUTC从40882.18hm^2减少到了18845.82hm^2,空间分布也呈现出沿环路越是靠近城市中心区域,其分布也越少的格局,从其类型上看,随着时间的推移,其类型的丰富度也越来越低,到2013年,则呈现出荒草地类型绝对占优的格局。PUTC的斑块数量从109892个减少为7793个,但斑块平均面积从2002年的0.37hm^2增加到了2013年的2.36hm^2,斑块大小格局也从2002年的小斑块占绝对优势演变为各种类型"平分秋色"的状况。以PUTC为核心的村(社区)区域潜力评价结果显示,整个研究区域在2002年时低潜力和中潜力区域范围最大,分别占到了研究区域的32.39%和28.83%,2013年时潜力格局改变为极低潜力和低潜力区域面积最大,分别占研究区域总面积的25.83%和50.94%。极高优先度和高优先度区域应该是北京城市未来重点发展城市森林的区域,目前的潜在优先度评价结果表明,其面积占比分别达到了研究区域面积的13.11%和41.79%,其中极高优先度区域主要分布在构成城市核心区的东城区和西城区,因此北京城区未来的林木树冠发展策略应该走植被潜在斑块与不透水地表潜在斑块共同开发之路。
