Visual preference of trees: The effects of tree attributes and seasons

Trees in cities are often viewed as objects of attraction. Previous literature suggests that some tree attributes, such as height, canopy size and leaf color, are the driving factors for a tree's aesthetic quality. However, the tree attributes used greatly vary among researchers who do not reach an agreement on which attributes affect people's preferences. Also, differences of trees' aesthetic quality in different seasons are poorly understood. To fill these gaps, twenty tree species were photographed in the exact same location in different seasonal stages, their aesthetic quality was judged by the general public using semi-quantitative response variable, and 11 tree attributes were abstracted and quantified to check their effect on the perception of trees' beauty. Statistical analysis showed that the tree possessing the characteristics of higher branching trunk, dense canopy and moderate length of leaves (about 11 cm) was given a high preference rank. Although there is no significant difference among preference scores in four seasons, the tree ranked a high preference in spring or summer was more likely to indicate an intense fluctuation of preference among four seasons. The practical implication is that more tree species with the preferred attributes should be used not only for aesthetic appeal but also for ecological benefits. For the contrast of aesthetic quality in different seasons, the trees which rank as high preference in spring or summer should be planted.