The status and trend on the urban tree canopy research

Urban tree and forest establishment is becoming one of the most significant approaches for combating the ecological and environmental problems associated with the rapid urbanization globally.The fragmentation of urban landscape and built-in facilities may leave less large scale open spaces for developing patchy forests and green spaces.Therefore,the urban tree canopy is one of the best indictors for quantitively and qualitively assessing urban forest characteristics thus a primary measure for urban forest planning and management.As a result,many communities are adopting Urban tree canopy(UTC) goals to maintain and improve forest benefits.UTC is defined as precentage of the leaves,branches and stems of trees that cover the ground when viewed from above.It is therefore widely used for evaluating water quality improvement,energy saving,urban heat island mitigation,air pollution reduction,property values adding,wildlife habitat conservation,social and educational opportunities,and aesthetic benefits that urban tree and forest can provide.UTC is relatively easy to measure by remote sensing technology and less costly than field sampling.UTC is a comparable index across a city and among cities whatever the size of the area is measured.In addition,UTC is a good performance measure for detecting changes across space and time and an easy-to-understand concept for communicating between managers and the public.The present development of UTC studies and applications can be summarized as 1) the UTC researches have firmly related with the eco-construction,people′s living and city management,2) the high resolution images are broadly utilizated in UTC investigation and maping,3) the Object-Based Image Analysis method and LIDAR technology are being applicated in the UTC research,and 4) the assistant artificial intelligence decision-making system will be popularized in the UTC construction and management.