Effects of Tree Leaf Color on Human Physical and Mental Recovery from a Looking-Up Perspective

Numerous studies have demonstrated the benefits of understory spaces and plants on human well-being, but most spatial research has focused on a horizontal perspective. Additionally, there is a lack of research on the effects of plant color on human recovery, especially with respect to color proportions. This study classifies the leaf colors of trees in autumn, which are observed from a looking-up perspective, into green, red, and yellow. On this basis, we created monochromatic, two-color, and three-color groups with varying color proportions to assess their recovery effects and preferences. A total of 30 participants participated in this experiment, and their physiological, psychological, and preference-related indicators were evaluated. The results revealed that the following. (1) The two-color groups had the greatest reduction effect on systolic blood pressure. Monochromatic groups were most effective at reducing diastolic blood pressure. The three-color groups had the greatest effect on lowering the pulse rate. (2) EEG responses varied by color type. (3) The three-color groups had the best recovery effects on the psychological measures. (4) The three-color groups were most favored by participants, with a red–yellow–green ratio of 0.2/0.4/0.4 being the most preferred. These findings demonstrate the differing recovery potentials of various leaf color proportions from a looking-up perspective. This study can provide valuable references for the planning and design of urban forest parks, supplementing the theoretical foundation and research framework for evaluating and creating environments that meet people’s restorative needs.