Microclimates and therapeutic effects of four forests on Southern Taihang Mountain

The therapeutic effects of forests have become a highlighted research focus in global health studies in recent years. The distinctive microclimate conditions and landscape aesthetics of forests have already been demonstrated to be beneficial for the rehabilitation of people’s physical and mental health. To advance the development of local forest therapy programs in the southern Taihang Mountain Range of North China, we investigated the therapeutic potential of four typical local forests: species-rich Pinus tabulaeformis forest (PTF) and Pinus bungeana forest (PBF), and species-poor Platycladus orientalis forest (POF) and Robinia pseudoacacia forest (RPF). This was done by assessing microclimate conditions and landscape aesthetics related to human health in these forests, while key stand characteristics determining landscape aesthetics were also explored. Microclimate conditions were monitored from June to October 2023, with monthly data collected from the 1st to the 4th of each month between 09:00 and 11:00 AM and diurnal variations recorded every two hours from 08:00 to 20:00 during September 1–4, while temperature, humidity and wind speed variables were integrated into a comprehensive climate comfort index (CCCI) as a surrogate for human comfort. Landscape aesthetics were evaluated with both eye-tracking technology and Scenic Beauty Estimation (SBE) method, which served as proxies for landscape visual perception. A structural equation model (SEM) was also developed to identify key forest characteristics determining landscape visual perception. The results showed that PM2.5 and bacterial concentrations in PTF and PBF were relatively lower than those in POF and RPF during summer and autumn. The CCCI values of PTF and PBF were 3.87 and 4.51, respectively, indicating superior air quality. Eye-tracking analysis revealed that PBF had the longest total gaze duration and highest number of gazes, possibly due to its trails, which provide high accessibility. SEM revealed that green coverage, tree height, shrub density, and herbaceous diversity jointly determined landscape visual quality (path coefficients: 0.98; 0.61; 0.71; –0.91), suggesting that integrated stand structure optimization is key to optimizing and enhancing these forests for their therapeutic values. These findings not only characterized the microclimate and aesthetic features of these forests but also identified key stand characteristics that affect their landscape aesthetics, providing a scientific basis for optimizing forest management works for forest therapy planning in the Taihang Mountains.