Human stress recovery response to landscapes is under discussion in Chinese settings. The present study aimed to clarify the stress recovery effects of campus street trees on graduate students in autumn. A total of 150 participants (23.75 ± 1.01 years old) completed the Trier Social Stress Test (TSST) and were then randomly assigned to view one of five virtual environments, including the street trees Sophora japonica, Ginkgo biloba, Platanus acerifolia, Koelreuteria paniculata, and the indoor environment (control). Physiological responses were measured by R-R interval and electroencephalography (EEG). Psychological responses were examined through the state version of the State-Trait Anxiety Inventory (STAI-S) and the Perceived Restorativeness Scale (PRS). Results showed that R-R intervals significantly increased while viewing all street trees. Both alpha and beta brainwave activities while viewing S. japonica and G. biloba were remarkably higher than those while viewing P. acerifolia and K. paniculata. The STAI-S scores significantly decreased, and the positive PRS scores were registered after viewing street trees. We concluded that a brief virtual visual experience of campus street trees in autumn has stress recovery effects on graduate students, and the different levels of stress recovery are associated with different types of street trees.

To address the question of whether the behavior of humans to view different phenological peony flowers has various effects on their physical and mental parameters, we investigated psycho-physiological responses of 74 participants (61.3 ± 10.78 years old) to environments of pre- and post-viewing tree peonies at four stages, including the exhibition leaf stage (ELS), initial bloom stage (IBS), full bloom stage (FBS), and terminal bloom stage (TBS). Physiological factors were examined using systolic blood pressure (SBP), diastolic blood pressure (DBP), heart rate (HR), fingertip pulse (FP), blood oxygen saturation (SpO₂), and psychological evaluation, which was carried out using the Profile of Mood States (POMS) and State–Trait Anxiety Inventory (STAI). The results indicated that the SBP, DBP, HR, and FP levels of participants were significantly reduced after viewing tree peonies, whereas no remarkable alterations in SpO₂ were found. The POMS scores of anger–hostility (A–H), fatigue–inertia (F–I), tension–anxiety (T–A), confusion–bewilderment (C–B), and depression–dejection (D–D) were significantly lower, but of vigor–activity (V–A) was higher post-viewing than pre-viewing. Furthermore, participants exhibited markedly decreased anxiety levels according to the STAI. Notably, the changes in measurement indices were more pronounced at the FBS. Our studies demonstrated that a short peony-viewing program, especially at the FBS with completely opened and large tree peony flowers, would be a promising therapeutic method for improving physiological functions as well as an effective psychological relaxation strategy for middle-aged and elderly individuals.

Background: The tree peony is an important ornamental plant with many cultivars and rich fragrances. The scents released from the flowers of various tree peony cultivars might impose different influences on psycho-physiological responses, which seem to be the gap in the present research.Methods: We investigated psycho-physiological responses of 80 students (23.9±2.25 years old) to the olfactory stimulation by the four types of tree peony fragrances, including the phenolic scent (PS), rose scent (RS), woody scent (WS), and lily of the valley scent (LVS). The present study assessed autonomic parameters such as heart rate (HR) and heart rate variability (HRV) to determine the arousal levels of the autonomic nervous system. Psychological evaluation was carried out using the Profile of Mood States (POMS) and semantic differential methods (SDM). Electroencephalography (EEG) was recorded during tree peony fragrance inhalation periods compared with control conditions.Results: The students exhibited significantly higher parasympathetic nervous activities, but significantly lower sympathetic nervous activities and heart rates after inhaling tree peony fragrances. The four kinds of tree peony fragrances induced significantly less negative and more vigorous moods, and obtained better scores in subjective evaluation, especially the rose scent. Furthermore, the analysis of EEGs showed a remarkable increase in the power of low alpha (8-10 Hz), high alpha (10-12 Hz), and theta (4-7 Hz) waves.Conclusions: Our studies demonstrated that a short olfactory stimulation with the four peony scents would be not only a promising therapeutic method for improving physiological function but also an effective psychological relaxation strategy for the participants.