204 Arboriculture & Urban Forestry 2008. 34(3):204–205. Arboricultural Abstracts ARBORICULTURAL ABSTRACTS PATTERN AND DIVERGENCE OF TREE COMMUNITIES IN TAIPEI’S MAIN URBAN GREEN SPACES C.Y. Jim and Wendy Y. Chen Urban vegetation increasingly contributes to nature conservation and ecosystem services, but lacking understanding of site varia- tions has restricted such uses. This study analyzed the spatial pattern and differentiation of tree communities in three major green landscape types (urban parks, riverside parks and street verges) in Taipei city. In each landscape type, 10 representative tree communities were studied. Statistical tests for ecological communities were employed: Jaccard and Q species similarity indices, two-way indicator species analysis (TWINSPAN), and new species fidelity, landscape fidelity and composite Q indices. Significant recent increase in Taipei’s green spaces was traced. The study area contained 164 tree species, but few were shared by the three landscape types and none by 30 communities. Na- tive evergreen broadleaf species with large final dimensions were dominant. Urban parks registered the highest species rich- ness, landscape fidelity, rare species and urban endemics. Such exclusive species constitution deviated notably from riverside parks and street verges, with relatively simple and converging intra-site species ingredients. Pronounced species differentiation between urban parks reflected diversified site topography, natu- ral woodland inheritance, woodland creation, and past landscape fashion. TWINSPAN classified the communities into nine groups each with signature characteristics. Inherent site varia- tions offered main determinants of tree heterogeneity, superim- posed by human modification to satisfy pre-determined site functions. A hybrid urban park with high species diversity and nature contents is advocated by amalgamating conventional but polarized designs of country and urban parks. The findings could inform management of urban forest, urban nature conservation, and ecological services of urban green spaces. (Landscape and Urban Planning 2008. 84(3–4):312–323) DEFENCE REACTIONS AND FUNGAL COLONISATION IN FRAXINUS EXCELSIOR AND TILIA PLATYPHYLLOS AFTER STEM WOUNDING F.W.M.R. Schwarze, J. Grüner, M. Schubert, and S. Fink Twenty 15-year-old ash and lime trees were each wounded by creating a chainsaw cut and an increment borer hole in May 2005. After sixteen months, trees were felled, dissected and the axial extent of both wood discoloration and barrier zone forma- tion associated with the wounds was greater in ash than in lime. Barrier zones extended only around part of the stem circumfer- ence in both species. In ash, the barrier zone consisted of 10–20 cell rows of axial parenchyma within the earlywood and a het- erogeneous matrix of libriform fibres, small vessels and concen- tric bands of 5–40 cell rows axial parenchyma within the late- wood. In lime, the barrier zone consisted of a homogeneous layer of axial and xylem ray parenchyma, in which the cell walls ©2008 International Society of Arboriculture showed suberisation, a low cellulose content and few pits. Fun- gal culturing from the discoloured wood of both species yielded mainly deuteromycetes (Fungi Imperfecti). Only one basidiomy- cete, Polyporus squamosus, was consistently isolated. The evi- dently high decay-resistance features of the barrier zone of lime trees may enhance the trees ability to remain alive and intact, even when extensive decay develops within their central, poorly defended wood as a result of severe wounding. The results of the present study suggest a possible explanation why ‘wall 4’ i.e. a defensive layer that forms within the first annual growth ring after damage, is more effective in lime than in ash. (Arboricul- tural Journal 2008. 30(1):1–22) ESTABLISHING A RELATIONSHIP BETWEEN SOIL AERATION AND FINE ROOT DEVELOPMENT OF SEVEN TREE SPECIES USING THE STEEL ROD TECHNIQUE Gary Watson Steel rods were driven into the soil in spring and summer within the root zone of seven different tree species: American Elm (Ulmus Americana L.), Green Column black maple (Acer ni- grum Michx. ’Green Column’), Green ash (Fraxinus pennsyl- vanica Marsh.), honeylocust (Gleditsia triacanthos), tuliptree (Liriodendron tulipifera L.), pin oak (Quercus palustris Muenchh.), and white oak (Quercus alba L.). After three months, the rods were extracted and the rusting pattern, an in- dicator of soil aeration, was assessed and correlated with fine root development (FRD). The correlation between FRD and soil aeration was high, indicating that FRD can be estimated by rusting. The steel rod technique may be a useful, low cost tool to help arborists evaluate soil aeration and FRD in urban land- scapes. In the field, rapid assessment of the rusting pattern would be possible. Predominantly rusted metal is a good indicator of soil suitable for good fine root development. Predominantly matt grey metal is an indicator of soil that may severely limit root development. (Arboricultural Journal 2006. 29(3):161–172) APPLICATION OF LAND SUITABILITY ANALYSIS AND LANDSCAPE ECOLOGY TO URBAN GREENSPACE PLANNING IN HANOI, VIETNAM Pham Duc Uy and Nobukazu Nakagoshi Urban green spaces, an important component of urban ecosys- tems, provide many environmental and social services that con- tribute to the quality of life in cities. One of the key tasks of planners is how to optimize the benefits of urban green spaces. This study introduces a program for developing green spaces in urban areas through (1) land suitability analysis based on GIS; (2) quantifying green areas based on the ecological factor thresh- old method to maintain ecological balance; and (3) applying landscape-ecology principles in organizing green spaces in urban areas. A case study was made for Hanoi, Vietnam and its results show that most of the planned green spaces in the 2020 Hanoi
May 2008
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