Comparing the Structure, Function, Value, and Risk of Managed and Unmanaged Trees along Rights-of-Way and Streets in Massachusetts

Round 1

Reviewer 1 Report

General comments:
The study stand on scientific approaches to clarify applied questions. The logic, analysis, and interpretations are generally fine. Although some results came up with unexpected patterns, they still provide comparative information for further understanding.

Specific comments:

- Since this paper has multiple authors, shouldn't the subject of the last three sentences be "we" rather than "I"? Otherwise, specify who!

- The conclusion in the abstract should be more informative.

- The "P" in "P-value" of Table 1 should be italic.

- Central alignment among lines in Table 2 should be revised. It is hard read data clearly.

Author Response

Reviewer 1:

The study stand on scientific approaches to clarify applied questions. The logic, analysis, and interpretations are generally fine. Although some results came up with unexpected patterns, they still provide comparative information for further understanding.

Thank you for the careful review of our submission; we have made the changes requested in the reviewer’s specific comments.

Specific comments:

- Since this paper has multiple authors, shouldn't the subject of the last three sentences be "we" rather than "I"? Otherwise, specify who!

We regret the oversight and have revised the text as requested.

- The conclusion in the abstract should be more informative.

We have revised the abstract as requested.

- The "P" in "P-value" of Table 1 should be italic.

We have revised text in Table 1 (and elsewhere) as requested.

- Central alignment among lines in Table 2 should be revised. It is hard read data clearly.

We have revised Table 2 accordingly.

Reviewer 2 Report

I am concerned by the degree of self-plagiarism. For example, the abstract is identical to Suttle's Master of Science thesis (https://doi.org/10.7275/24317002.0) which is available online. The paper must be carefully rewritten to ensure that this problem does not persist.

The abstract should be rewritten to include the key results and to outline the significance of the findings. 

The Introduction should be expanded to provide background to all the key topics that are pursued in the paper. Provide greater insight into the pruning of urban and peri-urban trees, canopy management, provision of ecosystem services, and the current methods used for tree risk assessment - risk of tree failure. Positioning the research in the context of the global literature is important (see for example PLOS ONE 16(2): e0246805. https://doi.org/10.1371/journal.pone.0246805).

Also in the Introduction, more strongly identify the research gap. It is generally known that trees under utility lines are managed differently from trees away from utility lines. How will this study compliment what has already been discussed extensively in the literature?

The findings of this study rely heavily on whether the trees were pruned or not pruned. The study states that "We noted the presence of pruning cuts on trees". A quantitative assessment of pruning should have been undertaken to better inform the findings. To what extent are trees under powerlines partially pruned compared to total top pruning - the extent of pruning can play a major role in tree form and C sequestration. To what extent were trees pruned away from powerlines? Local governments and administrative districts should be able to provide information on their operations around tree pruning as to whether it is done for amenity purposes or only for risk mitigation. Provide more descriptive information about this in the methods section regarding the study sites.

The study relies on the selection of utility and control plots but there were nearly twice as many trees in the utility as in the control plots. A more meaningful comparison would have been to have used paired plots with the same taxa. In any case, more information can be provided on criteria used to select the plots and whether there was any bias. Was there more historic tree death in the control plots? To what extent did tree height determine the extent of tree pruning that was undertaken in utility plots? 

Provide the tree data for the main species in a supplementary table.

Provide a figure showing key comparisons between the utility and control plots.

Provide more information on the Goodfellow's method as this is not widely known to readers of Forests outside North America.

Define what "percent crown missing" is and how it was determined.

Was the species distribution and tree spacing the same for the utility and control plots - if they differed, provide the historical background.

Provide a comparative analysis of the ecosystem services for the most common tree species in the study.

The odds ratio of unpruned trees was less than one, indicating that, compared to pruned trees, unpruned trees were less likely to have a greater likelihood of failure rating: Is this because trees of higher risk were pruned historically?

Where possible in the discussion, include studies by other authors - there is an over reliance on publications from the author's team.

 

 

 

 

 

Author Response

Reviewer 2:

I am concerned by the degree of self-plagiarism. For example, the abstract is identical to Suttle's Master of Science thesis (https://doi.org/10.7275/24317002.0) which is available online. The paper must be carefully rewritten to ensure that this problem does not persist.

We regret the confusion on this issue. At universities in the United States, theses and dissertations, even after they have been successfully defended, are not considered “peer-reviewed” or “refereed”. It is customary that students and their advisors publish scholarly, peer-reviewed manuscripts from theses and dissertations, and it is not considered self-plagiarism. Citation of theses and dissertations, especially because online versions are readily available, is discouraged because the expectation is that students and their advisors will publish the thesis or dissertation in a peer-reviewed journal. Since we have made many changes in accordance with reviewers’ comments, the revised manuscript does not follow the thesis as closely.

The abstract should be rewritten to include the key results and to outline the significance of the findings. 

We have revised the abstract in accordance with the reviewer’s request, as well as the comment of reviewer 1. 

The Introduction should be expanded to provide background to all the key topics that are pursued in the paper. Provide greater insight into the pruning of urban and peri-urban trees, canopy management, provision of ecosystem services, and the current methods used for tree risk assessment - risk of tree failure. Positioning the research in the context of the global literature is important (see for example PLOS ONE 16(2): e0246805. https://doi.org/10.1371/journal.pone.0246805).

We have revised and expanded the introduction (paragraphs 2 - 5) to elaborate on tree risk assessment, pruning, and provision of ecosystem services as they relate to our study.

Also in the Introduction, more strongly identify the research gap. It is generally known that trees under utility lines are managed differently from trees away from utility lines. How will this study compliment what has already been discussed extensively in the literature?

We have revised the final paragraph in the introduction to more clearly identify the research gap that we hoped to fill by conducting the study.

The findings of this study rely heavily on whether the trees were pruned or not pruned. The study states that "We noted the presence of pruning cuts on trees". A quantitative assessment of pruning should have been undertaken to better inform the findings. To what extent are trees under powerlines partially pruned compared to total top pruning - the extent of pruning can play a major role in tree form and C sequestration. We agree that quantifying the extent of pruning would have been a suitable alternative to our approach, especially in terms of how it influenced tree form and C sequestration and storage. We chose to sample more sites and measure trees less intensively rather than sample fewer sites and measure trees more intensively to include as large a sample as possible. This approach was requested by the sponsor to ensure that a wide range of growing conditions (5 USDA Hardiness Zones) and taxa would be included. Regarding pruning severity, all of the trees near utility lines had been pruned to accommodate the utility’s specified vertical and lateral clearances (2.4 m below the lines, 3.7 m adjacent to the lines, 4.9 m above the lines) and we have added text to the third paragraph in the Methods section and the second paragraph of the Discussion section to clarify.

To what extent were trees pruned away from powerlines? Local governments and administrative districts should be able to provide information on their operations around tree pruning as to whether it is done for amenity purposes or only for risk mitigation. Provide more descriptive information about this in the methods section regarding the study sites.

Unfortunately, it was not possible to know the pruning history of trees in control plots (away from the powerlines) because few if any communities keep detailed, long-term records of such activities. In addition, some trees in control plots were not in the public right-of-way and it was not possible to survey landowners regarding maintenance history. We have added text to the second paragraph of the Discussion section to note this limitation

The study relies on the selection of utility and control plots but there were nearly twice as many trees in the utility as in the control plots. A more meaningful comparison would have been to have used paired plots with the same taxa. 

As noted in previous responses, in accordance with the sponsor’s directive, we were more interested in gathering as large a sample as possible; consequently, we were not able to measure trees as intensively. Since trees were measured in situ, pairing plots to control for taxa while also controlling for growing conditions would have been prohibitively time-consuming and substantially reduced sample size. Randomly selecting a utility plot and pairing it with an adjacent control plot reasonably controlled for growing conditions, and the most common genera were represented in all four categories of the main effects (pruned, unpruned, control plot, utility plot).

In any case, more information can be provided on criteria used to select the plots and whether there was any bias.

We revised the first paragraph of the Methods section to include more details of how we selected sites and plots within each site. The software we used to generate random plots (ArcMap) has a proprietary algorithm and we reference it in the revision. The stratification layers we applied (sites were along roads in Eversource’s territory and assigned by census tract) were necessary for the sponsor and to ensure that more densely populated areas were sampled proportionally more frequently.

Was there more historic tree death in the control plots? 

Since detailed local records did not exist, it was unknowable whether there was more historic tree death leading to fewer trees in control plots. Anecdotally, it is more likely that fewer trees existed in control plots because utility plots less frequently occurred in proximity to residential development and trees were therefore maintained only with respect to the powerlines, not for aesthetic reasons.

To what extent did tree height determine the extent of tree pruning that was undertaken in utility plots? 

Trees were pruned in accordance with the utility’s line clearance standard which called for clearance of 2.4 m below the wires, 4.9 m above the wires, and 3.7 m adjacent to the wires. We noted the influence of tree height in sub-section 4.1 in the Discussion

Provide the tree data for the main species in a supplementary table.

We have added a supplementary table including DBH, height, structural value, and total annual benefits of trees in genera that made up ≥4% of the total sample.

Provide a figure showing key comparisons between the utility and control plots.

- We have added a supplementary figure showing box plots of the key results. 

Provide more information on the Goodfellow's method as this is not widely known to readers of Forests outside North America.

- We added text to the fourth paragraph in the Methods section as requested.

Define what "percent crown missing" is and how it was determined.

- We added a more detailed description of how to determine percent crown missing and directed readers to  the readily available iTree Eco User’s Manual [14] for more information on the procedure.

Was the species distribution and tree spacing the same for the utility and control plots - if they differed, provide the historical background.

- Distribution of the most common genera was similar among plots and pruning status, as shown in the supplementary table that we added in response to a previous comment. Unfortunately, there are no historical data for the sites and we did not measure tree spacing, which would have been prohibitively time-consuming. Since there were more trees in utility plots and all plots were the same dimensions, it follows that spacing between trees was smaller in utility plots.

Provide a comparative analysis of the ecosystem services for the most common tree species in the study.

- We have included total annual ecosystem services ($) per tree and structural value ($) per tree for the most common genera in the supplementary table that we added in response to a previous comment.

The odds ratio of unpruned trees was less than one, indicating that, compared to pruned trees, unpruned trees were less likely to have a greater likelihood of failure rating: Is this because trees of higher risk were pruned historically?

- Unfortunately, historical data for individual trees were not available.  In the final paragraph of sub-section 4.2 of the Discussion, we discussed the effects of pruning and tree size on likelihood of failure ratings.

Where possible in the discussion, include studies by other authors - there is an over reliance on publications from the author's team.

- We have cited 24 studies in the Discussion; only 6 are self-citations, which does not seem unreasonable since the self-citations are highly relevant. Since neither of the other reviewers made a similar request, we are reluctant to delete them.

Reviewer 3 Report

Article Comparing human structure, function, value and risk Aged and unmanaged trees along rights-of-way and streets in Massachusetts is an interesting article, but in order to be published, it still
needs some changes/completions.
The data about the origin of the authors, institution, location do not respect the template of the magazine. Please rewrite them accordingly.

Scientific names from Figure 2. Species distribution of trees (n = 2361); "other" included 244 individuals of 66 species or, 177 for individuals that could not be identified to species, 10 genera each of which comprised < 1% of 178 the total sample should be written in italics. Please correct.

In conclusion, the article is well structured, interesting for the scientific community. I believe that it is a type of study that can be replicated for other areas. Congratulations for the work done!  

 

Author Response

Reviewer 3:

Article Comparing human structure, function, value and risk Aged and unmanaged trees along rights-of-way and streets in Massachusetts is an interesting article, but in order to be published, it still

needs some changes/completions.

 

The data about the origin of the authors, institution, location do not respect the template of the magazine. Please rewrite them accordingly.

We regret the oversight and have revised the text accordingly.

 

Scientific names from Figure 2. Species distribution of trees (n = 2361); "other" included 244 individuals of 66 species or, 177 for individuals that could not be identified to species, 10 genera each of which comprised < 1% of 178 the total sample should be written in italics. Please correct.

We have italicized the genus and species for trees as requested.

 

In conclusion, the article is well structured, interesting for the scientific community. I believe that it is a type of study that can be replicated for other areas. Congratulations for the work done!  

We appreciate the reviewer’s thoughtful suggestions to improve the manuscript.

Round 2

Reviewer 2 Report

I am satisfied with the amendments and additions made by the authors