Disentangling the Cooling Effects of Transpiration and Canopy Shading: Case Study of an Individual Tree in a Subtropical City
Abstract
1. Introduction
2. Materials and Methods
2.1. Study Area and Field Experiments
2.2. Microclimate Simulation
2.3. Designing the Simulation Scenarios
2.4. Estimation of the Cooling Effect of Tree Transpiration and Canopy Shading
3. Results
3.1. Characteristics of Meteorological Conditions During the Experiment Period
3.2. Characteristics of the Combined Cooling Effects of Tree Transpiration and Shading
3.3. Model Validation of the Simulated Temperature
3.4. Respective Cooling Effects of Tree Transpiration and Canopy Shading
4. Discussion
4.1. Tree Cooling Effects and Thermal Response Patterns
4.2. Dynamic Shifts in the Dominant Cooling Mechanism
4.3. Limitations and Future Research
5. Conclusions
- (1)
- The annual combined cooling effect of F. concinna is 0.31 ± 0.46 °C. This combined cooling effect has a clear unimodal variation pattern both seasonally and diurnally. The combined cooling effect exponentially increases as air temperatures rise and notably increases under higher temperature conditions (such as during heat waves).
- (2)
- The shade cooling effect of the F. concinna is highly sensitive to solar radiation. Canopy shading could substantially reduce the amount of shortwave radiation reaching the ground surface during the daytime, especially on clear summer days when peak cooling could reach up to 0.63 °C. During the night, however, the canopy attenuates longwave radiation loss and results in local warming.
- (3)
- F. concinna has a significant transpiration cooling effect, and it has a strong positive correlation with air temperature, with a maximum cooling effect of 1.03 °C.
Author Contributions
Funding
Data Availability Statement
Conflicts of Interest
References
- Yuan, Y.; Santamouris, M.; Xu, D.; Geng, X.; Li, C.; Cheng, W.; Su, L.; Xiong, P.; Fan, Z.; Wang, X.; et al. Surface urban heat island effects intensify more rapidly in lower income countries. npj Urban Sustain. 2025, 5, 11. [Google Scholar] [CrossRef]
- Portela, C.I.; Massi, K.G.; Rodrigues, T.; Alcântara, E. Impact of urban and industrial features on land surface temperature: Evidences from satellite thermal indices. Sust. Cities Soc. 2020, 56, 102100. [Google Scholar] [CrossRef]
- Rajagopal, P.; Priya, R.S.; Senthil, R. A review of recent developments in the impact of environmental measures on urban heat island. Sust. Cities Soc. 2023, 88, 104279. [Google Scholar] [CrossRef]
- Wang, J.; Zhou, W.; Pickett, S.T.A.; Yu, W.; Li, W. A multiscale analysis of urbanization effects on ecosystem services supply in an urban megaregion. Sci. Total Environ. 2019, 662, 824–833. [Google Scholar] [CrossRef]
- Guerreiro, S.B.; Dawson, R.J.; Kilsby, C.; Lewis, E.; Ford, A. Future heat-waves, droughts and floods in 571 European cities. Environ. Res. Lett. 2018, 13, 34009. [Google Scholar] [CrossRef]
- IPCC. Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change; Cambridge University Press: Cambridge, UK; New York, NY, USA, 2021. [Google Scholar]
- Kim, S.W.; Brown, R.D. Urban heat island (UHI) intensity and magnitude estimations: A systematic literature review. Sci. Total Environ. 2021, 779, 146389. [Google Scholar] [CrossRef]
- Buchin, O.; Hoelscher, M.; Meier, F.; Nehls, T.; Ziegler, F. Evaluation of the health-risk reduction potential of countermeasures to urban heat islands. Energy Build. 2016, 114, 27–37. [Google Scholar] [CrossRef]
- Scherer, D.; Fehrenbach, U.; Lakes, T.; Lauf, S.; Meier, F.; Schuster, C. Quantification of heat-stress related mortality hazard, vulnerability and risk in Berlin, Germany. Die Erde 2014, 144, 238–259. [Google Scholar]
- Schinasi, L.H.; Benmarhnia, T.; De Roos, A.J. Modification of the association between high ambient temperature and health by urban microclimate indicators: A systematic review and meta-analysis. Environ. Res. 2018, 161, 168–180. [Google Scholar] [CrossRef] [PubMed]
- Kumar, P.; Sharma, A. Study on importance, procedure, and scope of outdoor thermal comfort—A review. Sust. Cities Soc. 2020, 61, 102297. [Google Scholar] [CrossRef]
- Deilami, K.; Kamruzzaman, M.; Liu, Y. Urban heat island effect: A systematic review of spatio-temporal factors, data, methods, and mitigation measures. Int. J. Appl. Earth Obs. Geoinf. 2018, 67, 30–42. [Google Scholar] [CrossRef]
- Georgescu, M.; Morefield, P.E.; Bierwagen, B.G.; Weaver, C.P. Urban adaptation can roll back warming of emerging megapolitan regions. Proc. Natl. Acad. Sci. USA 2014, 111, 2909–2914. [Google Scholar] [CrossRef] [PubMed]
- Lai, D.; Lian, Z.; Liu, W.; Guo, C.; Liu, W.; Liu, K.; Chen, Q. A comprehensive review of thermal comfort studies in urban open spaces. Sci. Total Environ. 2020, 742, 140092. [Google Scholar] [CrossRef] [PubMed]
- Sadeghi, M.; Chaston, T.; Hanigan, I.; de Dear, R.; Santamouris, M.; Jalaludin, B.; Morgan, G.G. The health benefits of greening strategies to cool urban environments–A heat health impact method. Build. Environ. 2022, 207, 108546. [Google Scholar] [CrossRef]
- Paschalis, A.; Chakraborty, T.C.; Fatichi, S.; Meili, N.; Manoli, G. Urban forests as main regulator of the evaporative cooling effect in cities. Agu Adv. 2021, 2, e2020AV000303. [Google Scholar] [CrossRef]
- Schwaab, J.; Meier, R.; Mussetti, G.; Seneviratne, S.; Bürgi, C.; Davin, E.L. The role of urban trees in reducing land surface temperatures in European cities. Nat. Commun. 2021, 12, 6763. [Google Scholar] [CrossRef]
- Ziter, C.D.; Pedersen, E.J.; Kucharik, C.J.; Turner, M.G. Scale-dependent interactions between tree canopy cover and impervious surfaces reduce daytime urban heat during summer. Proc. Natl. Acad. Sci. USA 2019, 116, 7575–7580. [Google Scholar] [CrossRef]
- Bowler, D.E.; Buyung-Ali, L.; Knight, T.M.; Pullin, A.S. Urban greening to cool towns and cities: A systematic review of the empirical evidence. Landsc. Urban Plan. 2010, 97, 147–155. [Google Scholar] [CrossRef]
- Sabrin, S.; Karimi, M.; Nazari, R.; Pratt, J.; Bryk, J. Effects of Different Urban-Vegetation Morphology on the Canopy-level Thermal Comfort and the Cooling Benefits of Shade Trees: Case-study in Philadelphia. Sustain. Cities Soc. 2021, 66, 102684. [Google Scholar] [CrossRef]
- Wang, C.; Wang, Z.H.; Yang, J. Cooling effect of urban trees on the built environment of contiguous United States. Earth’s Future 2018, 6, 1066–1081. [Google Scholar] [CrossRef]
- Qiu, G.Y.; Yu, X.; Wen, H.; Yan, C. An advanced approach for measuring the transpiration rate of individual urban trees by the 3D three-temperature model and thermal infrared remote sensing. J. Hydrol. (Amst.) 2020, 587, 125034. [Google Scholar]
- Winbourne, J.B.; Jones, T.S.; Garvey, S.M.; Harrison, J.L.; Wang, L.; Li, D.; Templer, P.H.; Hutyra, L.R. Tree transpiration and urban temperatures: Current understanding, implications, and future research directions. Bioscience 2020, 70, 576–588. [Google Scholar] [CrossRef]
- Massetti, L.; Petralli, M.; Napoli, M.; Brandani, G.; Orlandini, S.; Pearlmutter, D. Effects of deciduous shade trees on surface temperature and pedestrian thermal stress during summer and autumn. Int. J. Biometeorol. 2019, 63, 467–479. [Google Scholar] [CrossRef]
- Rahman, M.A.; Moser, A.; Rötzer, T.; Pauleit, S. Microclimatic differences and their influence on transpirational cooling of Tilia cordata in two contrasting street canyons in Munich, Germany. Agric. For. Meteorol. 2017, 232, 443–456. [Google Scholar] [CrossRef]
- Rahman, M.A.; Stratopoulos, L.M.F.; Moser-Reischl, A.; Zölch, T.; Häberle, K.; Rötzer, T.; Pretzsch, H.; Pauleit, S. Traits of trees for cooling urban heat islands: A meta-analysis. Build. Environ. 2020, 170, 106606. [Google Scholar] [CrossRef]
- Chen, X.; Zhao, P.; Hu, Y.; Ouyang, L.; Zhu, L.; Ni, G. Canopy transpiration and its cooling effect of three urban tree species in a subtropical city-Guangzhou, China. Urban For. Urban Green. 2019, 43, 126368. [Google Scholar] [CrossRef]
- Lindén, J.; Fonti, P.; Esper, J. Temporal variations in microclimate cooling induced by urban trees in Mainz, Germany. Urban For. Urban Green. 2016, 20, 198–209. [Google Scholar] [CrossRef]
- Shashua-Bar, L.; Hoffman, M.E. Vegetation as a climatic component in the design of an urban street: An empirical model for predicting the cooling effect of urban green areas with trees. Energy Build. 2000, 31, 221–235. [Google Scholar] [CrossRef]
- Kim, J.; Khouakhi, A.; Corstanje, R.; Johnston, A.S.A. Greater local cooling effects of trees across globally distributed urban green spaces. Sci. Total Environ. 2024, 911, 168494. [Google Scholar] [CrossRef] [PubMed]
- Li, H.; Zhao, Y.; Wang, C.; Ürge-Vorsatz, D.; Carmeliet, J.; Bardhan, R. Cooling efficacy of trees across cities is determined by background climate, urban morphology, and tree trait. Commun. Earth Environ. 2024, 5, 754. [Google Scholar] [CrossRef]
- Jiao, M.; Zhou, W.; Zheng, Z.; Wang, J.; Qian, Y. Patch size of trees affects its cooling effectiveness: A perspective from shading and transpiration processes. Agric. For. Meteorol. 2017, 247, 293–299. [Google Scholar] [CrossRef]
- Wu, Z.; Shi, Y.; Ren, L.; Hang, J. Scaled outdoor experiments to assess impacts of tree evapotranspiration and shading on microclimates and energy fluxes in 2D street canyons. Sust. Cities Soc. 2024, 108, 105486. [Google Scholar] [CrossRef]
- Tan, P.Y.; Wong, N.H.; Tan, C.L.; Jusuf, S.K.; Chang, M.F.; Chiam, Z.Q. A method to partition the relative effects of evaporative cooling and shading on air temperature within vegetation canopy. J. Urban Ecol. 2018, 4, 1–11. [Google Scholar] [CrossRef]
- Pace, R.; De Fino, F.; Rahman, M.A.; Pauleit, S.; Nowak, D.J.; Grote, R. A single tree model to consistently simulate cooling, shading, and pollution uptake of urban trees. Int. J. Biometeorol. 2021, 65, 277–289. [Google Scholar] [CrossRef] [PubMed]
- Manickathan, L.; Defraeye, T.; Allegrini, J.; Derome, D.; Carmeliet, J. Parametric study of the influence of environmental factors and tree properties on the transpirative cooling effect of trees. Agric. For. Meteorol. 2018, 248, 259–274. [Google Scholar] [CrossRef]
- Yu, H.; Zhang, T.; Fukuda, H.; Ma, X. The effect of landscape configuration on outdoor thermal environment: A case of urban Plaza in Xi’an, China. Build. Environ. 2023, 231, 110027. [Google Scholar] [CrossRef]
- Zheng, X.; Chen, L.; Yang, J. Simulation framework for early design guidance of urban streets to improve outdoor thermal comfort and building energy efficiency in summer. Build. Environ. 2023, 228, 109815. [Google Scholar] [CrossRef]
- Marchin, R.M.; Backes, D.; Ossola, A.; Leishman, M.R.; Tjoelker, M.G.; Ellsworth, D.S. Extreme heat increases stomatal conductance and drought-induced mortality risk in vulnerable plant species. Glob. Change Biol. 2022, 28, 1133–1146. [Google Scholar] [CrossRef]
- Hayat, M.; Xiang, J.; Yan, C.; Xiong, B.; Wang, B.; Qin, L.; Saeed, S.; Hussain, A.; Zou, Z.; Qiu, G.Y. Environmental control on transpiration and its cooling effect of Ficus concinna in a subtropical city Shenzhen, southern China. Agric. For. Meteorol. 2022, 312, 108715. [Google Scholar] [CrossRef]
- Zhang, Y.; Chiew, F.H.S.; Peña-Arancibia, J.; Sun, F.; Li, H.; Leuning, R. Global variation of transpiration and soil evaporation and the role of their major climate drivers. J. Geophys. Res. Atmos. 2017, 122, 6868–6881. [Google Scholar] [CrossRef]
- Toparlar, Y.; Blocken, B.; Maiheu, B.; van Heijst, G.J.F. A review on the CFD analysis of urban microclimate. Renew. Sustain. Energy Rev. 2017, 80, 1613–1640. [Google Scholar] [CrossRef]
- Salata, F.; Golasi, I.; de Lieto Vollaro, R.; de Lieto Vollaro, A. Urban microclimate and outdoor thermal comfort. A proper procedure to fit ENVI-met simulation outputs to experimental data. Sust. Cities Soc. 2016, 26, 318–343. [Google Scholar] [CrossRef]
- Le, A.; Chan, Y. Comparison between ENVI-met and ANSYS-fluent when used for microclimate simulation. J. Phys. Conf. Ser. 2023, 2600, 82019. [Google Scholar] [CrossRef]
- Simon, H.; Lindén, J.; Hoffmann, D.; Braun, P.; Bruse, M.; Esper, J. Modeling transpiration and leaf temperature of urban trees–A case study evaluating the microclimate model ENVI-met against measurement data. Landsc. Urban Plan. 2018, 174, 33–40. [Google Scholar] [CrossRef]
- Liu, Z.; Cheng, W.; Jim, C.Y.; Morakinyo, T.E.; Shi, Y.; Ng, E. Heat mitigation benefits of urban green and blue infrastructures: A systematic review of modeling techniques, validation and scenario simulation in ENVI-met V4. Build. Environ. 2021, 200, 107939. [Google Scholar] [CrossRef]
- Wang, B.; Yan, C.; Shi, Z.; Ding, J.; Zhang, T.; Qin, L.; Qiu, G.Y. Seasonal variation in water uptake patterns of two greening species and their responses to rainfall events in a subtropical megacity of China. J. Hydrol. 2023, 618, 129262. [Google Scholar] [CrossRef]
- Cheng, K.Y.; Lau, K.; Shek, Y.T.; Liu, Z.; Ng, E. Evaluation on the performance of tree view factor in a high-density subtropical city: A case study in Hong Kong. Build. Environ. 2023, 239, 110431. [Google Scholar] [CrossRef]
- Bruse, M. ENVI-Met Implementation of the Jacobs A−gs Model to Calculate the Stomata Conductance. Available online: http://www.envi-met.net/documents/new_a_gs.pdf (accessed on 16 February 2004).
- Cheng, X.; Peng, J.; Dong, J.; Liu, Y.; Wang, Y. Non-linear effects of meteorological variables on cooling efficiency of African urban trees. Environ. Int. 2022, 169, 107489. [Google Scholar] [CrossRef] [PubMed]
- de Abreu-Harbich, L.V.; Labaki, L.C.; Matzarakis, A. Effect of tree planting design and tree species on human thermal comfort in the tropics. Landsc. Urban Plan. 2015, 138, 99–109. [Google Scholar] [CrossRef]
- Kong, F.; Yan, W.; Zheng, G.; Yin, H.; Cavan, G.; Zhan, W.; Zhang, N.; Cheng, L. Retrieval of three-dimensional tree canopy and shade using terrestrial laser scanning (TLS) data to analyze the cooling effect of vegetation. Agric. For. Meteorol. 2016, 217, 22–34. [Google Scholar] [CrossRef]
- Zhang, L.; Zhan, Q.; Lan, Y. Effects of the tree distribution and species on outdoor environment conditions in a hot summer and cold winter zone: A case study in Wuhan residential quarters. Build. Environ. 2018, 130, 27–39. [Google Scholar] [CrossRef]
- Lambers, H.; Chapin, F.S.; Pons, T.L. Plant Water Relations. In Plant Physiological Ecology; Lambers, H., Chapin, F.S., Pons, T.L., Eds.; Springer: New York, NY, USA, 2008; pp. 163–223. [Google Scholar]
- Morakinyo, T.E.; Kong, L.; Lau, K.K.; Yuan, C.; Ng, E. A study on the impact of shadow-cast and tree species on in-canyon and neighborhood’s thermal comfort. Build. Environ. 2017, 115, 1–17. [Google Scholar] [CrossRef]
- Wujeska-Klause, A.; Pfautsch, S. The best urban trees for daytime cooling leave nights slightly warmer. Forests. 2020, 11, 945. [Google Scholar] [CrossRef]
- Shashua-Bar, L.; Pearlmutter, D.; Erell, E. The cooling efficiency of urban landscape strategies in a hot dry climate. Landsc. Urban Plan. 2009, 92, 179–186. [Google Scholar] [CrossRef]
- Yu, Z.; Chen, J.; Chen, J.; Zhan, W.; Wang, C.; Ma, W.; Yao, X.; Zhou, S.; Zhu, K.; Sun, R. Enhanced observations from an optimized soil-canopy-photosynthesis and energy flux model revealed evapotranspiration-shading cooling dynamics of urban vegetation during extreme heat. Remote Sens. Environ. 2024, 305, 114098. [Google Scholar] [CrossRef]
- Pataki, D.E.; McCarthy, H.R.; Litvak, E.; Pincetl, S. Transpiration of urban forests in the Los Angeles metropolitan area. Ecol. Appl. 2011, 21, 661–677. [Google Scholar] [CrossRef] [PubMed]
- Zhu, Y.; Cheng, Z.; Feng, K.; Chen, Z.; Cao, C.; Huang, J.; Ye, H.; Gao, Y. Influencing factors for transpiration rate: A numerical simulation of an individual leaf system. Therm. Sci. Eng. Prog. 2022, 27, 101110. [Google Scholar] [CrossRef]
- Rai, P.K.; Chutia, B.M.; Patil, S.K. Monitoring of spatial variations of particulate matter (PM) pollution through bio-magnetic aspects of roadside plant leaves in an Indo-Burma hot spot region. Urban For. Urban Green. 2014, 13, 761–770. [Google Scholar] [CrossRef]
- Rai, P.K. Impacts of particulate matter pollution on plants: Implications for environmental biomonitoring. Ecotoxicol. Environ. Saf. 2016, 129, 120–136. [Google Scholar] [CrossRef]
Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content. |
© 2025 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).
Share and Cite
Shi, Z.; Yan, C.; Hu, W.; Luo, Z.; Qiu, G.Y. Disentangling the Cooling Effects of Transpiration and Canopy Shading: Case Study of an Individual Tree in a Subtropical City. Forests 2025, 16, 1564. https://doi.org/10.3390/f16101564
Shi Z, Yan C, Hu W, Luo Z, Qiu GY. Disentangling the Cooling Effects of Transpiration and Canopy Shading: Case Study of an Individual Tree in a Subtropical City. Forests. 2025; 16(10):1564. https://doi.org/10.3390/f16101564
Chicago/Turabian StyleShi, Zhe, Chunhua Yan, Weiting Hu, Zifan Luo, and Guo Yu Qiu. 2025. "Disentangling the Cooling Effects of Transpiration and Canopy Shading: Case Study of an Individual Tree in a Subtropical City" Forests 16, no. 10: 1564. https://doi.org/10.3390/f16101564
APA StyleShi, Z., Yan, C., Hu, W., Luo, Z., & Qiu, G. Y. (2025). Disentangling the Cooling Effects of Transpiration and Canopy Shading: Case Study of an Individual Tree in a Subtropical City. Forests, 16(10), 1564. https://doi.org/10.3390/f16101564