Microclimates and therapeutic effects of four forests on Southern Taihang Mountain

Abstract

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.

Graphical Abstract

Keywords

Forest microclimate / PM2.5 / Comprehensive climate comfort index / Eye-tracking / Forest therapy / Taihang Mountains

References

[1] Amati M, Ghanbari Parmehr E, McCarthy C, Sita J. How eye-catching are natural features when walking through a park? Eye-tracking responses to videos of walks. Urban for Urban Green, 2018, 31: 67-78.

[2] Assefa S, Ventura M, Bravo F, Giberti GS, Olivar J, Bielak K, Tonon G, Wellstein C. Pure and mixed Scots pine forests showed divergent responses to climate variation and increased intrinsic water use efficiency across a European-wide climate gradient. Eur J Res, 2024, 144: 875-892.

[3] Bielinis E, Takayama N, Boiko S, Omelan A, Bielinis L. The effect of winter forest bathing on psychological relaxation of young Polish adults. Urban Urban Green, 2018, 29: 276-283.

[4] Chen L, Shan B, Wang L, Li W, Shui C, Liu Y. The spatiotemporal evolution and contributing factors of PM2.5 and O3 concentrations in Shandong Province from 2014–2023. Environ Monit Assess, 2025, 197(9): 1074

[5] Cvikl D. The development of a forest tourism attractiveness model and a foundational framework for forest climatic spa resorts: an attributive theory approach. Forests, 2025, 16(7): 1149.

[6] Davidar P, Sahoo S, Mammen PC, Acharya P, Puyravaud JP, Arjunan M, Garrigues JP, Roessingh K. Assessing the extent and causes of forest degradation in India: where do we stand?. Biol Conserv, 2010, 143(10): 2937-2944.

[7] Ding Y, Qu H, Qu H. A dose–response curve of restorative benefits of plant communities: based on visual distances and yellow to green hue range. J for Res, 2026, 37(2): 1-21.

[8] Dong L, Jiang H, Li W, Qiu B, Wang H, Qiu W. Assessing impacts of objective features and subjective perceptions of street environment on running amount: a case study of Boston. Landsc Urban Plan, 2023, 235: 104756.

[9] Feng S, Tong K, Li M, Gong B. Characteristics and influencing factors of air microorganism of different green spaces on university campus in winter and spring. J Northwest for Univ, 2023, 38(3): 235-241.

[10] Füger F, Huth F, Wagner S, Weber N. Can visual aesthetic components and acceptance be traced back to forest structure?. Forests, 2021, 12(6): 701.

[11] Gao J, Newberry MG. Scaling in branch thickness and the fractal aesthetic of trees. PNAS Nexus, 2025, 4(2): pgaf003.

[12] Gao T, Liu F, Wang Y, Mu S, Qiu L. Reduction of atmospheric suspended particulate matter concentration and influencing factors of green space in urban forest park. Forests, 2020, 11(9): 950.

[13] Gao Y, Zhang T, Zhang W, Meng H, Zhang Z. Research on visual behavior characteristics and cognitive evaluation of different types of forest landscape spaces. Urban for Urban Green, 2020, 54: 126788.

[14] Gobster PH, Kruger LE, Schultz CL, Henderson JR. Key characteristics of forest therapy trails: a guided, integrative approach. Forests, 2023, 14(2): 186.

[15] Grilli G, Sacchelli S. Health benefits derived from forest: a review. Int J Environ Res Public Health, 2020, 17(17): 6125.

[16] Guo D, Xu T, Luo J, Wang X, Lin S, Lin C, Hong Y, Chang W. The evidence for stress recovery in forest therapy programs: investigating whether forest walking and guided forest therapy activities have the same potential?. J for Res, 2025, 36(1): 1-16.

[17] Hu P, Han Y, Zhang Z, Chu SC, Pan JS. A multi-level thresholding image segmentation algorithm based on equilibrium optimizer. Sci Rep, 2024, 14(1): 29728

[18] Huang S, Qi J, Li W, Dong J, van den Bosch CK. The contribution to stress recovery and attention restoration potential of exposure to urban green spaces in low-density residential areas. Int J Environ Res Public Health, 2021, 18(16): 8713.

[19] Lan Y, Liu Q, Zhu Z. Exploring landscape design intensity effects on visual preferences and eye fixations in urban forests: insights from eye tracking technology. Forests, 2023, 14(8): 1628.

[20] Li Q. Effects of forest environment (Shinrin-yoku/Forest bathing) on health promotion and disease prevention —the establishment of "Forest Medicine". Environ Health Prev Med, 2022

[21] Li X, Wu D, Li L, Wang X. Research on visual perception evaluation of urban riverside greenway landscape based on deep learning. J Beijing Univ, 2022, 43(12): 93-104.

[22] Li C, Du C, Ge S, Tong T. An eye-tracking study on visual perception of vegetation permeability in virtual reality forest exposure. Front Public Health, 2023, 11: 1089423.

[23] Li K, Zou Y, Wang H, Chen S. Exploring the relationship between the tourist behavior and the spatial characteristics for rural tourism. Sci Rep, 2025, 15(1): 9229

[24] Liang D, Huang G. Influence of urban tree traits on their ecosystem services: a literature review. Land, 2023, 12(9): 1699.

[25] Lis A, Iwankowski P. Why is dense vegetation in city parks unpopular? The mediative role of sense of privacy and safety. Urban for Urban Green, 2021, 59: 126988.

[26] Liu Q, Wang X, Liu J, An C, Liu Y, Fan X, Hu Y. Physiological and psychological effects of nature experiences in different forests on young people. Forests, 2021, 12(10): 1391.

[27] Liu R, Shao M, Wang Q. Multi-timescale variation characteristics of PM2.5 in different regions of China during 2014–2022. Sci Total Environ, 2024, 920: 171008

[28] Lyu M, Lin J, Zhou F, Niu J, Sun D, Meng Y, Ji X. A method for evaluating the visual quality of wetland park landscapes: a case study of Qianlu Lake wetland park in Wuping, China. Environ Res Commun, 2024, 6(10): 105024.

[29] Madhavi Latha K, Highwood EJ. Studies on particulate matter (PM10) and its precursors over urban environment of Reading, UK. J Quant Spectrosc Radiat Transfer, 2006, 101(2): 367-379.

[30] McMullen N, Annesi-Maesano I, Renard JB. Impact of rain precipitation on urban atmospheric particle matter measured at three locations in France between 2013 and 2019. Atmosphere, 2021, 12(6): 769.

[31] Miao C, Li P, Huang Y, Sun Y, Chen W, Yu S. Coupling outdoor air quality with thermal comfort in the presence of street trees: a pilot investigation in Shenyang, Northeast China. J for Res, 2023, 34(3): 831-839.

[32] Park BJ, Tsunetsugu Y, Kasetani T, Kagawa T, Miyazaki Y. The physiological effects of Shinrin-yoku (taking in the forest atmosphere or forest bathing): evidence from field experiments in 24 forests across Japan. Environ Health Prev Med, 2010, 15(1): 18-26.

[33] Pateraki St, Assimakopoulos VD, Maggos Th, Fameli KM, Kotroni V, Vasilakos Ch. Particulate matter pollution over a Mediterranean urban area. Sci Total Environ, 2013, 463: 508-524.

[34] Qin S, Hu C, Zhang Y, Wang Y, Dong W, Li X. Advances in nitrogen footprint research. Chin J Eco-Agric, 2011, 19(2): 462-467.

[35] Rahmandari AV, Gunawan A, Mugnisjah WQ. An evaluation of visual aesthetic quality of pedestrian pathways based on ecological network corridor within campus landscape. IOP Conf Ser Earth Environ Sci, 2018, 179: 012010.

[36] Rodrigues AR, Marques S, Botequim B, Marto M, Borges JG. Forest management for optimizing soil protection: a landscape-level approach. For Ecosyst, 2021, 8(1): 50.

[37] Sharafatmandrad M, Khosravi Mashizi A. Visual value of rangeland landscapes: a study based on structural equation modeling. Ecol Eng, 2020, 146: 105742.

[38] Shen Y, Wang Q, Liu H, Luo J, Liu Q, Lan Y. Landscape design intensity and its associated complexity of forest landscapes in relation to preference and eye movements. Forests, 2023, 14(4): 761.

[39] Shi H, Zhang F, Shi Q, Li M, Dai Y, Zhang Z, Zhu C. Responses of arid plant species diversity and composition to environmental factors. J for Res, 2023, 34(6): 1723-1734.

[40] Świątek AH, Szcześniak M, Stempień M, Wojtkowiak K, Chmiel M. The mediating effect of the need for cognition between aesthetic experiences and aesthetic competence in art. Sci Rep, 2024, 14(1): 3408

[41] Wang M, Liu J. Evaluation of the potential effects of forest vegetation cover on surface temperature in different geographical and climatic regions of Shaanxi Province, China. CATENA, 2025, 255: 109020.

[42] Wang R, Zhao J, Meitner MJ. Urban woodland understory characteristics in relation to aesthetic and recreational preference. Urban for Urban Green, 2017, 24: 55-61.

[43] Wang H, Liu G, Li Z, Zhang L, Wang Z. Processes and driving forces for changing vegetation ecosystem services: insights from the Shaanxi Province of China. Ecol Indic, 2020, 112: 106105.

[44] Wang Y, Liu G, Jiang M, Yang Q, Chen Q, Li X, Luo Z, Song H, Du J, Yu X, Lv B, Li N. Effects of forest spatial types, element compositions and forest stands on restorative potential and aesthetic preference. Front for Glob Change, 2023, 6: 1218134.

[45] Wang Y, Yang G, Lu Y. Evaluation of urban wetland landscapes based on a comprehensive model—a comparative study of three urban wetlands in Hangzhou, China. Environ Res Commun, 2023, 5(3): 035004.

[46] Wang C, Ren Z, Zhang P, Guo Y, Hong S, Hong W, Wang X, Geng R, Meng F. Impact of vegetation coverage and configuration on urban temperatures: a comparative study of 31 provincial capital cities in China. J for Res, 2024, 35(1): 142.

[47] Wei Q, Chen Y, Zhang H, Jia Z, Yang J, Niu B. Simulation and prediction of PM2.5 concentrations and analysis of driving factors using interpretable tree-based models in Shanghai, China. Environ Res, 2025, 270: 121003

[48] Wu Q, Fang Z, Song Z, Chen H, Lu Y, Zhou L, Qian X. A color extraction algorithm by segmentation. Sci Rep, 2023, 13(1): 1-11.

[49] Xu J, Zhang Y, Zhang D, Zhu F, Zhao H. Jincheng city tourism climate resource analysis and evaluation. Sci Technol Innov, 2021, 1: 157-158.

[50] Yang B, Ma R, Zhai J, Du J, Bai J, Zhang W. Stand spatial structure is more important than species diversity in enhancing the carbon sink of fragile natural secondary forest. Ecol Indic, 2024, 158: 111449

[51] Zhang W, Zhao J, Luo J. Evaluation on climate comfortable degree in Yunhe. J Hebei Agric Sci, 2010, 14(10): 142-143.

[52] Zhang H, Hua Y, Liu H, Lu S. Influence of haze on air microbial concentrations in the student activity areas. Med Compr Exp Cent Hebei Univ, 2018, 39(4): 592-594.

[53] Zhao Q, Zhou Y, Zhai J. Bridging beauty and biodiversity: coupling diversity and aesthetics through optimized plant communities in urban riverfront landscapes. Sci Total Environ, 2024, 950: 175278

[54] Zhao Y, Li J, Jin Y, Au TF, Cui D, Chen Z. Divergent growth and responses of conifer and broad-leaved trees to warming-drying climate in a semi-arid region, northern China. Eur J for Res, 2024, 143(3): 887-901.

[55] Zhao J, Fu X, Sa N, Kou X, He X, Zheng S, Lu Z, Wu G, Sang W. Forest eco-function restoration and its positive effects on biodiversity improvement in China’s ecological conservation programs. Ecol Eng, 2025, 212: 107530.

[56] Zheng S, Zhou Y, Qu H. Physiological and psychological responses to tended plant communities with varying color characteristics. J for Res, 2024, 35(1): 32.

[57] Zou H, Zhang H. Landscape structures and stand attributes jointly regulate forest productivity. Oikos, 2024, 2024(12): e10749.

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