270 Arboricultural Abstracts ATTITUDES TOWARD URBAN GREEN SPACES: INTEGRATING QUESTIONNAIRE SURVEY AND COLLABORATIVE GIS TECHNIQUES TO IMPROVE ATTITUDE MEASUREMENTS Shivanand Balram and Suzana Dragicevic Attitudes influence behavior toward urban green spaces. But determining attitudes toward urban green spaces is not well operationalized in urban planning research. A study was conducted in the West Island, Montréal, Canada, to elaborate the design and development of a valid and reliable instru- ment to measure the dimensions of citizen attitudes toward urban green spaces. The use of qualitative and quantitative phases in the instrument design strengthened the operationalization of the attitude concept. In the qualitative stage, a novel approach integrating collaborative geographic information system (GIS) techniques and informal interviews generated complementary insights about the spatial and nonspatial factors influencing attitude towards urban green spaces. Affinity analysis aggregated the issues into three homogeneous categories that guided the construction of questionnaire items. A self-administered mail-back question- naire was developed and distributed to 322 households using a multistage cluster sampling strategy; 179 questionnaires were returned (55.6%). In the quantitative phase, factor analysis and reliability analysis were applied to the items set to create a valid attitude measurement scale. The analysis shows that households are characterized by a two-factor attitude structure toward urban green spaces: behavior and usefulness. It is concluded that urban green spaces attitude is a multi-dimensional construct. The implications for green spaces planning are outlined. (Landsc. Urban Plann. 2005. 71:147–162) DEVELOPMENT OF A DISEASE SEVERITY RATING SCALE FOR PLANE TREE ANTHRACNOSE María-Luisa Tello, Cristina Redondo, Laura Gaforio, Silvina Pastor, and Eloy Mateo-Sagasta Anthracnose caused by the fungus Apiognomonia veneta (Sacc. et Speg.) H hnel., is the most important and frequent disease affecting mature ornamental plane trees (Platanus × hybrida Brot.= P. × acerifolia (Ait.)Willd.) of central Spain. Symptoms of the disease are leaf vein and petiole necrosis, bud death, defoliation, proliferation of shoots growing in whorls, short internodes, cankers, necrotic lesions, and twigs and branches growing in angles. Based on our previous experience, a disease severity rating scale (DSRS) has been established, consisting of six levels: 0 = healthy, 1 = initial, 2 = low, 3 = medium, 4 = high, and 5 = dead. In order to achieve a better and more efficient measure of disease intensity, we tried to quantify this visual scale using mathematical criteria. In 2000, 610 mature trees up to 200 years old, divided into four age classes, were selected and systematically evaluated using a visual estimation based method. The trees were located in central Spain, mainly in ©2005 International Society of Arboriculture two periurban areas of the town of Aranjuez (south of Madrid) and in three urban areas of Madrid city. Trees were observed in late spring, summer, and winter. We recorded visual estimation of disease severity, foliage cover, healthy new shoots, dead branches, shoot growth in whorls, and branch growth in angles. The statistical relationship between the parameters, disease severity, and all the variables recorded (defoliation, healthy new shoots, etc.) has been evaluated. “Leaf density,” “dead branches,” and “healthy shoots” were the variables that help to discriminate better between the different levels of the DSRS. A clearer definition of the different phases of disease severity will facilitate the application of possible control methods and the prediction of the behavior of other Platanus spp. (Urban For. Urban Green. 2005. 3:93–101) PATTERNS IN HYDRAULIC ARCHITECTURE AND THEIR IMPLICATIONS FOR TRANSPORT EFFICIENCY Katherine A. McCulloh and John S. Sperry entire plant with maturation. These patterns coexist in innumerable combinations depending on the ratio of distal/ proximal conduit number (F). The model of West and colleagues does not account for this diversity, in part by specifying F = 1 and requiring a specific conduit taper derived from the incorrect premise that kL We evaluated whether patterns in hydraulic architecture increase transport efficiency. Five patterns are identified: area- preserving branching; variable trunk versus twig sap velocity; distally decreasing leaf specific conductivity (KL diameter; and a decline in leaf specific conductance (kL is constant with plant size. We used Murray’s law to identify the conduit taper that maximizes kL greater the kL requires the ratio of distal/proximal conduit diameter to equal the ratio of distal/proximal KL for a given vascular investment. Optimal taper . The smaller these ratios, the . Smaller ratios are achieved by an increase in F. Conductivity and diameter ratios < 1 and F 1 in plants are therefore consistent with maximizing conducting efficiency. However, the benefit of increasing F requires area-increasing conduit branching, potentially leading to mechanical instabil- ity of trees. This trade-off may explain why tree stems were relatively inefficient with F near 1 and limited conduit taper compared with vine stems or compound leaves with F > 1 and greater taper. Within trees, the anatomies of a coniferous and a diffuse-porous species were less efficient than those of a ring- porous species, presumably because the latter allows conduit area to increase distally without also increasing total xylem area. This is consistent with decelerating sap velocities from trunk to twigs in ring-porous trees versus accelerating veloci- ties in other types. In general, the observed architectural patterns are consistent with the maximization of transport efficiency operating within mechanical constraints. (Tree Physiol. 2005. 25:257–267) ) and conduit ) of the
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