Table of Contents C.Y. Jim Multipurpose Census Methodology to Assess Urban Forest Structure in Hong Kong ....................................... 366 Abstract. Surveys of urban forests in the compact city environment of Hong Kong were initiated in 1985 and regularly updated thereaf- ter. Roadside trees were evaluated first in a tree census and reported in this article followed by urban parks, public housing estates, and spe- cial habitats such as old stone walls or special specimens such as heritage trees. The survey method aimed at collecting comprehensive data to echo both tree conditions and tree–environmental interactions. Detailed information was gleaned, with the help of well-trained assis- tants, on tree sites, tree growing space, tree structure, and tree defects and disorders. A field record form was designed, pilot-tested, and refined to solicit responses to multiple choices or direct measurements to minimize subjectivity and errors in data recording and entry. The study also identified potential planting sites, registering suitability for tree growth, site characteristics, and dimensions. Data fields were designed to be quantitative or convertible to ordinal ranks to facilitate statistical analysis. Locations of trees and planting sites were marked on large-scale maps to permit spatial analysis. Besides statistical analysis, community ecology attributes and custom-designed indi- ces were used to assess urban forest structure. The multipurpose method could be appropriately adjusted for use in other compact city areas. Key Words. Compact City; Forest Structure; Heritage Tree; Hong Kong; Planting plan; Species Composition; Species Diversity; Tree Census. Zhu Hua Ning, Xing Yuan He, Chang Fu Liu, and Kamran K. Abdollahi Assessing Urban Forest Structure and Health in Shenyang, China ...................................................................... 379 Abstract. 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 loca- tion, function, and management objectives, the urban forests were classified into five cover types: landscape forests, ecologic forests, road for- ests, 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 increas- ing 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. David J. Nowak, Jeffrey T. Walton, Jack C. Stevens, Daniel E. Crane, and Robert E. Hoehn Effect of Plot and Sample Size on Timing and Precision of Urban Forest Assessments ..................................... 386 Abstract. Accurate field data can be used to assess ecosystem services from trees and to improve urban forest management, yet little is known about the optimization of field data collection in the urban environment. Various field and Geographic Information System (GIS) tests were performed to help understand how time costs and precision of tree population estimates change with varying plot and sample sizes in urban areas using random sampling approaches. Using one-tenth acre (0.04 ha) plots, it is estimated that, on average, approximately three plots per day can be measured with plot data collected on several variables for all trees greater than 1 in (2.54 cm) in diameter along with general plot, ground cover, and shrub data. A field crew of two people can gather approximately 200 one-tenth acre (0.04 ha) plots during a 14 week summer field season depending on city traffic, city area, and tree cover conditions. These 200 plots typically yield approximately a 12% relative standard error on the total number of trees. Key Words. Tree Measurement; Urban Forest Monitoring; Urban Forest Sampling. David J. Nowak Assessing Urban Forest Structure: Summary and Conclusions ........................................................................... 391 ©2008 | International Society of Arboriculture | ISSN:1935-5297
November 2008
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