384 Ning et al.: Assessing Urban Forest Structure and Health bungeana, and Ginkgo biloba grow very well in Shenyang and can be used in future planting to increase diversity and for their high aesthetic values. Size distribution of the trees in Shenyang is very similar to the Figure 9. Health condition of different types of urban forests. L = landscape forests; R = road forest; P = park forest; E = ecologic forest; C = commercial forest. Shrub Species Composition, Size, and Health Condition There are a total of 232,548 shrubs of 39 species in the urban area; most common shrub species are ranked by frequency in Table 1. Seventy-seven percent of the shrubs are less than 3 m (10 ft) tall (Figure 6C), and ninety-four percent are in good health condition (Figure 8C). Compared among urban forest types, the average health condition index (Figure 9) of the shrubs along roads is the lowest, and the shrubs in the commercial nurseries and orchards are the highest followed by shrubs in public parks, forest parks, scenic areas, and historical places. In the suburban area, shrubs are found in the park forests and eco- logic forests. There are a total of 706,617 shrubs of 16 species in the suburban area. Compared with the urban area, the number of shrubs in the suburbs is 67% higher and the number of species is 59% lower. Compared with the urban area, the major shrub species are different, the size is smaller, and the health condition is similar (Table 1; Figures 6D, 8D, and 9). CONCLUSIONS We hope that this study demonstrates the feasibility and useful- ness of urban forest assessment and monitoring in China. Results presented in this article only document baseline urban forest structure and health conditions. The refinement of the methods used in this study will result in a data collection protocol that can be used to assess and monitor urban trees and detect changes in their condition, status, and health. Urban vegetation management in China places major empha- sis on the absolute quantity of greenspace such as total area of urban vegetation, total canopy cover, and per capita vegetation cover and overlooks other structural attributes of urban vegeta- tion as indicators of improvement in urban greening plans (Yang et al. 2008). To establish a better urban forest structure and maximize the ecologic benefits, Shenyang, through its urban planning and greening efforts, should increase its urban forest cover by enhancing the tree planting in the city center, southeast and outskirts of the city, in the newly developed residential areas, along roads, and in the parks. The city’s North Canal can be used as a corridor to connect the urban forest from the east to the west. The connectivity of the urban forest patches in the urban landscape may be critical for maintaining the species population and diversity (Zipperer et al. 2000). Species diversity should be one of the priorities in future planting and greening efforts. Assessment showed that species such as Tilia mandshurica, Sophora japonica, Koelreuteria bi- pinnata, Pinus armandi, Acer truncatum, Tilia amurensis, Celtis ©2008 International Society of Arboriculture results presented by Yang et al. (2005) of the urban forest struc- ture study in Beijing. The lack of large trees presents a problem for proper carbon dioxide and pollution sequestration, carbon storage, and other ecologic benefits that larger trees can provide (Nowak and Crane 2002; Nowak et al. 2002). Most trees and shrubs are in good to very good health condition and have rela- tively small dbh and height. There are more species in the urban areas than in the suburbs and the major tree species composition is very different. The species occurrence and distribution in both urban and suburban areas are strongly influenced by the species’ natural occurrences and manmade disturbances. Compared with the suburbs, the spe- cies in the urban area are more introduced than native. This trend affects the suburban species composition as well. More native species are being replaced by the introduced species. As Shenyang expands its urban area as a result of urban develop- ment, it is anticipated that the species composition will change drastically in the suburbs. In the suburbs, massive tree planting efforts for the purpose of establishing forest plantations have both positive and negative outcomes. It is anticipated that these forest plantations will pro- vide economic and ecologic benefits. However, the use of only a few species such as Pinus tabuliformis and Robinia pseudo- acacia may result in an even aged and nearly single species plantation that is not ecologically sound. Acknowledgments. The results presented in this article are from a por- tion of a project entitled Urban Forest Ecology funded by the Chinese Academy of Sciences (CAS) with project number C99AD-BR010502 and project director Dr. Zhu H. Ning. The research is also supported by the Foundation of Knowledge Innovation Program of the Chinese Acad- emy of Sciences with project number KZCX3-SW-43 and project di- rector Dr. Zhu H. Ning. Special thanks go to the project team members at the CAS Institute for Applied Ecology, Shenyang, China, under the leadership of Director Dr. Xing Y. He. Special credits for the field study, data collection, and analysis for this article go to Dr. Chang F. Liu. LITERATURE CITED Council of Tree and Landscape Appraisers. 2000. Guide for Plant Appraisal. 9th Edition. International Society of Arboriculture, Cham- paign, IL. Dwyer, J.F., D.J. Nowak, M.H. Noble, and S.M. Sisinni. 2000. Con- necting People With Ecosystems in the 21 Century: An Assessment of Our Nation’s Urban Forests. General Technical Report PNW- GTR-490. USDA Forest Service, Pacific Northwest Research Sta- tion, Portland, OR. 483 pp. Godefroid, S., and N. Koedam. 2007. Urban plant species patterns are highly driven by density and function of built-up areas. Landscape Ecology 22:1227–1239. McPherson, E.G., D.J. Nowak, G. Heisler, S. Grimmond, C. Souch, R. Grant, and R. Rowntree. 1997. Quantifying urban forest structure, function, and value: The Chicago urban forest climate project. Urban Ecosystems 1:49–61. Miller, R.W. 1997. Urban Forestry: Planning and Managing Urban Green Spaces. Prentice Hall, Upper Saddle River, NJ. Nowak, D.J. 1992. Remote sensing and urban forestry. Proceedings of the Society of American Foresters 1992 National Convention. ———. 1994. Understanding the structure of urban forests. Journal of Forestry 92:42–46.
November 2008
| Title Name |
Pages |
Delete |
Url |
| Empty |
Search Text Block
Page #page_num
#doc_title
Hi $receivername|$receiveremail,
$sendername|$senderemail wrote these comments for you:
$message
$sendername|$senderemail would like for you to view the following digital edition.
Please click on the page below to be directed to the digital edition:
$thumbnail$pagenum
$link$pagenum
Your form submission was a success. You will be contacted by Washington Gas with follow-up information regarding your request.
This process might take longer please wait
