The Impact of Trees on the UHI Effect and Urban Environment Quality: A Case Study of a District in Pisa, Italy

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

General comments:

This manuscript presents a comprehensive investigation into the ecosystem services provided by urban trees and their impact on the Urban Heat Island (UHI) effect in a district of Pisa, Italy. The authors’ approach of comparing three different street settings - large trees, small trees, and no trees - using a combination of field data and software simulations is commendable for its comprehensiveness. The study effectively bridges urban forestry with urban climatology, offering a multifaceted perspective on environmental management in urban settings. However, there are areas in which the manuscript could be improved to enhance its scientific rigor and overall impact. I recommend publication after these revisions are made.

 

Detailed Comments:

Title: The current title only addresses the impact of urban trees on UHI and air quality, disregarding the broader range of ecological services they provide. Hence, it fails to capture the comprehensive scope of the research.

Abstract: The abstract should also include important findings and conclusions of this study.

L53: The emission of BVOCs from urban trees emerges as a significant negative ecosystem service, as highlighted in the referenced literature below. Therefore, it is essential to include this aspect in the literature review section. Moreover, considering that the i-Tree model provides a module for calculating tree BVOC emissions, it would be advantageous for the authors to consider incorporating it into this study, given its direct relevance to air quality.

Ref1: Role of Biogenic Volatile Organic Compounds (BVOC) emitted by urban trees on ozone concentration in cities: A review

Ref2: Role of Management Strategies and Environmental Factors in Determining the Emissions of Biogenic Volatile Organic Compounds from Urban Greenspaces

Methodological Clarification: The methodology section would benefit from more detailed descriptions of the data collection process, particularly how the sites were selected and any controls used to ensure data consistency.

Since the i-Tree model is a “black box” software, it is crucial for the authors to provide a list of core algorithms used for calculating various ecosystem services and the data requirements associated with them. This information is highly necessary for readers.

Results Interpretation: While the results are interesting, they would benefit from a deeper analysis, particularly in understanding the causal relationships between tree cover and UHI/air quality effects.

Discussion of Implications: The discussion could be expanded to explore the implications of these findings for urban planning and policy, particularly in contexts similar to Pisa.

Author Response

Please see the attachment.

Sincerely Yours

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

Article by Greta Frosini, Agnese Amato, Francesca Mugnai and Fabrizio Cinelli "Impact of Urban Trees on UHI and Air Quality: a case study of a district in Pisa" is devoted to the study of the impact of changing the type of trees or their complete cutting down on urban ecology in the summer conditions of a coastal Mediterranean city (Pisa, Italy).
This is an important topic, especially in the context of a changing climate and increasing content of impurities in the atmosphere.
The importance of preserving large trees, which most contribute to mitigating the summer heat and removing pollution from the atmosphere, is shown.
Note that the article relates more to the topic of urban sustainable development than to atmospheric physics.

MAJOR COMMENTS

The authors' main goal is to study influence of trees on urban ecology. This issue seems to be well studied in various parts of the world, so it is surprising how few references in the Introduction to such studies and few comparisons with their results in the Discussion. In this regard, it is necessary to expand the Introduction and add more comparisons to the Discussion.
As can be seen from Figure 3c authors talk about sidewalks without trees rather streets without trees. It might make sense to replace “streets” with “sidewalks” throughout in the text or to note in the Materials and Methods section that “streets” mean sidewalks.
Please indicate in Materials and Methods on the base of what criteria the day of the measurements was selected among the other days of a week.
Authors used meteorological data of 2015 year as "most recent data available", is there really no data for at least for 2020?
In the Materials and Methods section, it should be described method for taking thermograms, as well as the manufacturer and brand of the thermal imager should be indicated.

MINOR NOTES
Line 2 (title): please replace "UHI"->"Urban Heat Island": abbreviation met firstly should be written fully.
Lines 3 (title) and 69: it is need to add "Tuscany, Italy" after "Pisa".
Line 24: please add "UHI" after "Urban Heat Island".
Line 32: please add "UE" after "urban environment".
Lines 33-34: no need in abbreviations of GI, NBS and ES since they are not used further.
Line 76: please provide more detail information what runoff is meant.
Line 86: please replace "river Arno" -> "Arno River", "Ligurian sea" -> "Ligurian Sea".
Line 87: please add "(Pisan Mountains)" after "Monti Pisani".
Line 90: please replace "Valdarno" -> "Vadarno Valley of the Arno River".
Line 91: please replace "temperature" -> "surface air temperature".
Line 92: please add link to database used.
Lines 123, 131, 135 and 290: please replace "global" with "total". "Global" is related to Earth as whole.
Line 152: please replace "with the aid of" wuth "using".
Line 154: please replace "e" with "and".
Line 171: please provide manufacturer and model of the WBGT meter used.
Line 187: "WBGT in outdoor with solar radiation is calculated by:"->"WBGT in outdoor with solar radiation, WGBTo [°C], is calculated by:".
Line 189: "WBGT indoor and outdoor without solar radiation is calculated by:"->"WBGT indoor and outdoor without solar radiation, WGBTi [°C], is calculated by:".
Lines 236 and 242: please replace "Figure 3" with "Figure 4".
Lines 245 and 250: please replace "Figure 4" with "Figure 5".
Line 253: please replace "Tnw" with "Tw".
Lines 253 and 258: please replace "Figure 5" with "Figure 6".
Line 275: no one word about methodics of obtaining thermograms.
Line 275: please replace "Figures 6,7 and 8" with "Figures 7,8 and 9".
Line 278: please replace "Figure 6" with "Figure 7".
Lines 313-320: it seems it should be in Introduction rather in Discussion.

 

Comments on the Quality of English Language

Minor editing of English language required (please see Minor Notes in the Comments window)

Author Response

Minor notes:

Line 92 (now 100): database is now linked (reference n. 41)  

Please see the attachment.

Sincerely Yours

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors The approach used in the study to evaluate air quality and UHI is solid and well-documented. However, further information about the precise tools and techniques utilised for data collecting might improve the research's openness. Please add latest reference related to heat wave and UHI  like https://doi.org/10.1016/j.uclim.2023.101622, https://doi.org/10.1007/s00704-021-03854-z, etc. When examining the effects of urban trees, it is important to take both the geographical and temporal factors into account. The distribution of trees throughout the area and how seasonal fluctuations may affect patterns of air quality and UHI should be covered in the study. A comparison with similar studies conducted in other urban areas can strengthen the generalizability of the findings. It would be interesting to see how the results align or differ from research in different climates or geographical settings. The practical effectiveness of the research would be increased by a more thorough description of how the findings may influence urban planning and policy decisions.   Mentioning that the summer of 2023 was used for data collecting. More context would be added by discussing the reasoning behind selecting this season and considering how seasonal fluctuations affect the outcomes. providing more details on the specific metrics used within i-Tree Eco would enhance the transparency of the analysis. Provide reason behind the selection of the four representative roads to enhance the understanding of their impact on the overall findings.  
To add depth to the study, briefly address how tree age and diversity may affect how they affect air quality and Urban Heat Island (UHI).

Please provide the details related to the different colours used in Table 5.

Please provide the discussion and conclusion separately. The limitations of the study should be explicitly stated. Guidance for researchers interested in advancing this topic could also be given in the form of recommendations for future study directions. Hence, it is recommended to provide the limitations and future scope of your present study. Discuss the potential impact of the study's conclusions on green space management and urban design choices in the 'Porta a Lucca' district and possibly elsewhere in cities.
 

Author Response

We have better highlighted the differences between conclusions, limitations of the research and future developments so we have not separated discussion and conclusions.

Please see the attachment

Sincerely Yours

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

I have carefully reviewed the revised manuscript and would like to express my satisfaction with the authors' thorough revisions. They have successfully addressed all the concerns I raised in my previous review. The changes made have significantly improved the quality and clarity of the paper.