Assessing Urban Forest Structure and Health in Shenyang, China

This article summarizes the assessment of the urban forest structure and health in central areas of Shenyang, China. Urban forest cover analysis was conducted using aerial photographs, satellite imagery, and a field survey of 282 plots as major study methods. Based on the location, function, and management objectives, the urban forests were classified into five cover types: landscape forests, ecologic forests, road forests, park forests, and commercial forests. Total tree cover in the study area is 7.85%. Most trees and shrubs are in good to very good health and have relatively small diameter at breast height and height. The major tree species are different in urban and suburban areas, which was the result of the natural occurrence of the species and manmade disturbances. Major recommendations for the future management include increasing urban forest cover, especially in the city center, east side, and outskirts; and increasing species diversity and urban forest connectivity. Key Words. Distribution; health condition; species composition; tree cover; urban forest structure. Over the past 10 to 15 years, urban expansion has been occurring more rapidly than at any time in China. Currently, approximately 41% of China's people are living in cities, compared with 26% at the end of the 1980s, and the country is still rapidly urbanizing (Wu et al. 2008). Thus, city greening and urban forestry have become very important issues, because many Chinese cities have air pollution problems. Urban forest is one of the defining fea- tures of a city and a region. Proper urban forest structure and health are the cornerstones of urban forest sustainability, because they strongly influence the urban forest function and benefits. Urban forest structure and health assessment is highly important because it provides crucial characteristics of the green infra- structure (Smith et al. 2005). Many urban forest management questions could be quickly and effectively addressed using geo- spatial methods and tools (Ward and Johnson 2007). The geo- spatial tools can provide timely and extensive spatial data from which urban forest attributes can be derived such as land cover, forest structure, species composition and condition, heat island effects, and carbon storage. However, the ground survey meth- ods must be used along with the geospatial methods to increase the accuracy of the study results. To promote urban forestry and to obtain baseline information for better management decisions and practices, an urban forest assessment was conducted in central Shenyang, China. The as- sessment has many objectives and the objectives related to this article were to establish, for the first time in the history of Shenyang, permanent urban forest assessment plots for the first assessment and future assessments; to assess urban forest struc- ture such as urban forest cover, cover types, species composition, size, location, and distribution; and to assess the overall urban forest health.