Exploring the Potential of SCOPE Model for Detection of Leaf Area Index and Sun-Induced Fluorescence of Peatland Canopy
, Michal Antala 1, Egor Prikaziuk 2, Peiqi Yang 2,3, Christiaan van der Tol 2 and Radoslaw Juszczak 1
Round 1
Reviewer 1 Report
Comments for author File: 
Comments.pdf
Author Response
Reviewer1: Rastogi et al. Exploring the dynamic nature of peatland through the measurement of ground-level remote sensing and radiative transfer models. Submitted to: Remote Sensing. Manuscript ID: remotesensing-1821127 General Comments: This manuscript is a fairly straightforward study that examines the extent to which ground-level remote sensing approaches, coupled with the SCOPE radiative transfer model, can be used to estimate leaf area index and sun-induced fluorescence in a Polish peatland where there were preexisting warming and precipitation manipulations. The data, analysis, and interpretations all seem reasonable to me. Response: Thank you for your appreciating words There actually has been a reasonable amount of work on remote sensing in peatlands; it is surprising that the literature has not been cited in this manuscript (especially review #2 from Chasmer et al., and possibly other papers in the Special Issue of Remote Sensing). A few references are listed below. Given this rather large literature, it’s not clear what is novel about this manuscript. Perhaps it is the coupling of the ground-based measurements with a radiative transfer model. Kalacska et al. (2015) Estimation of foliar chlorophyll and nitrogen content in an ombrotrophic bog from hyperspectral data: Scaling from leaf to image Remote Sensing of the Environment 169: 270- 279. McPartland et al. (2019) Characterizing Boreal Peatland Plant Composition and Species Diversity with Hyperspectral Remote Sensing. Remote Sensing 11: 4685 Chasmer et al. (2020) Remote Sensing of Boreal Wetlands 1: Data Use for Policy and Management. Remote Sensing 12, 1320 Chasmer et al. (2020) Remote Sensing of Boreal Wetlands 2: Methods for Evaluating Boreal Wetland Ecosystem State and Drivers of Change. Remote Sensing 12, 1321 Czapiewski S, Szuminska D (2021) An Overview of Remote Sensing Data Applications in Peatland Research Based on Works from the Period 2010–2021. Land 11: 24 Response: We have cited the related work to show the advancement and application of remote sensing in peatland as suggested. Specific Comments: The manuscript does state three objectives at the end of the Introduction, but the first one is not especially helpful. If the other two are retained, I’d suggest structuring the Discussion around these two objectives. Response: Deleted the 1st objective, and discussion is around the objectives. Delete the last sentence of the Introduction. Response: Deleted From a peatland ecosystem science perspective, however, there are few things that the author might consider. The Introduction states “In addition, different types of vegetation that coexist make the peatlands a complex system. Therefore, monitoring peatland vegetation is needed to have an idea about this ecosystem in a rapidly changing environment.” I’m not sure I agree that different kinds of vegetation make the peatlands a complex system. This is a pretty subjective statement. Response: We meant different evolutionary forms of vegetation coexist together such as Bryophytes, pteridophytes, gymnosperms and angiosperms, which makes the ecosystem complex as each evolutionary form has different needs and peatland has to fulfil all. We have clarified the sentence in the revised MS. The phrase “…to have an idea…” is not especially strong. Deleted The Introduction also states: “Monitoring of the peatland vegetation directly by personal surveys and measurements is very difficult or impossible considering their distribution in the boreal zone, often in very remote areas and waterlogged, life-threatening conditions.” This is very much of an overstatement. Monitoring of vegetation and/or changes over time, is time consuming, but not necessarily difficult if done by appropriately trained individuals. I’ve never heard a peatland ecologist say that they work under life-threatening conditions. Modified Further, if one is interested in how species composition changes over time, there is no substitute for traditional vegetation assessments. Agree, and we do not claim that Methods (and discussion) – The Rzecin peatland seems to be an unusual kind of peatland. The authors refer to a rich-poor fen gradient. In this regard, water chemistry (pH, reduced conductivity) would be useful. We are measuring the water chemistry, and conductivity, which can be found in our other papers (Górecki, K.; Rastogi, A.; Stróżecki, M.; Gąbka, M.; Lamentowicz, M.; Łuców, D.; Kayzer, D.; Juszczak, R. Water table depth, experimental warming, and reduced precipitation impact on litter decomposition in a temperate Sphagnum-peatland. Sci. Total Environ. 2021, 771, 145452.). Whereas the purpose of this paper is to apply the SCOPE model for LAI and SIF prediction. Moreover, it is not a boreal peatland. How relevant this study is to boreal peatlands world-wide is unclear. Response: As the vegetation types are similar to Rzecin in Boreal peatland, we expect this study should be applicable to boreal peatland too. Discussion – Much of the Discussion seems to be more results than interpretation. The Discussion could be shortened and made more tightly focused. Structuring around the stated objectives would help to accomplish this. Response:We have tried to justify the discussion with the addition of references, but could not shorten it as here we discussed the results and provided the logic why certain observation was observed. We further added the conclusion.Author Response File: Author Response.pdf
Reviewer 2 Report
Dear authors,
Your manuscript “Exploring the dynamic nature of peatland through the measurement of ground-level remote sensing and radiative transfer models” is not ready for publication, because of the following issues.
· The Conclusion part is missing
· Any formula, as in Table 1 or the middle of page 4, needs a description for each parameter.
· Please also add a description of the statistical methods, especially the calculation of r and r2. For example: in Figure 4, you present correlation values although you wrote that these are r2 values. The formula for this statistic will help to clarify this issue.
Another issue, although it is not mandatory for the publication, but will be interesting for the reader, is to present the correlation values between the SIF, measured and modeled, and the remote sensing indices (the same as Figure 4, presenting the correlation between these indices and the LAI values). Doing so, it will help o understand which spectral indices from these you tested, is better to map the SIF.
In addition, I have small issues to correct as I marked in the original pdf file. Next time, please ensure to number each line so it will be easier to inform you about these small corrections.
Comments for author File: Comments.pdf
Author Response
Reviewer 2
Your manuscript “Exploring the dynamic nature of peatland through the measurement of ground-level remote sensing and radiative transfer models” is not ready for publication, because of the following issues.
- The Conclusion part is missing
Added
- Any formula, as in Table 1 or the middle of page 4, needs a description for each parameter.
Provided, the formula in the middle of page 4 was deleted, as we feel these are described in SCOPE-related modelling paper.
- Please also add a description of the statistical methods, especially the calculation of r and r2. For example: in Figure 4, you present correlation values although you wrote that these are r2values. The formula for this statistic will help to clarify this issue.
Added and clarified
Another issue, although it is not mandatory for the publication, but will be interesting for the reader, is to present the correlation values between the SIF, measured and modeled, and the remote sensing indices (the same as Figure 4, presenting the correlation between these indices and the LAI values). Doing so, it will help o understand which spectral indices from these you tested, is better to map the SIF.
Provided
In addition, I have small issues to correct as I marked in the original pdf file. Next time, please ensure to number each line so it will be easier to inform you about these small corrections.
All the suggestions provided in pdf are implemented.
The line number is added to revision, to further ease the review process
Reviewer 3 Report
Exploring the dynamic nature of peatland through the measurement of ground-level remote sensing and radiative transfer models by Rastogi et al. (2022)
To investigate the dynamic nature of peatland, this study uses the ground level remote sensing measurements and radiative transfer model SCOPE to retrieve and estimate several important vegetation indexes, such as LAI, SIF, NDVI, EVI and NIRv. The good correlation between measured and modeled SIF indicates that a reliable SIF value can be estimated through the SCOPE model for peatland vegetation, which is very useful when high-resolution hyperspectral measurement is not available. In general, this paper is well structured and easy to follow. However, I do believe that there is a need for extensive language edits and improvement. Moreover, this paper is more a description of results and figures, without sufficient explanation on physical mechanisms. Therefore, I would commend this manuscript being published in Remote Sensing once my concern has been addressed. Please see my specific comments as below.
What are the uncertainties or weaknesses of the SCOPE model? Please add some discussion.
Page 1: “But to have an understanding of satellite remote sensing there is need to have studies at the ground level.” Please rephrase the sentence.
Page 2: “These all phenomena lead to the dynamic behavior of peatland remote sensing signal which is different from the signals of the other ecosystems.” Please rephrase the sentence.
Page 2: “Even if the LAI is an important factor for ecosystem understanding its measurement/estimation is not easy, due to spatial and temporal heterogeneity.” Do you want to say measuring/estimating LAI is not easy?
Page 2: “Direct methods are the most accurate but tedious and time-consuming and can be destructive, whereas ground-based methods are based on radiation transmittance while remote sensing methods are based on reflectance.” This sentence is too long and hard to follow. Please rephrase it.
Page 3: I would recommend adding a map to mark the Pzecin peatland as well as CL and CR sites.
Page 4: Table 1: Part of formula for EVI is missing.
Page 6: “The modeled LAI obtained through the inversion of the SCOPE model showed a clear seasonal pattern, where the value of LAI started to go high with each measurement until it reaches its peak in July after that it tends to decrease towards its starting value for both the sites.” Please consider replacing “go high” with “increase”; removing “the” in the “both the sites”.
Page 6: “There were no statistically significant differences among treatments for any day of measurement, except mod-eled LAI on 16th June for CR vegetation (Supplement 1) when LAI of W is significantly higher than LAI of C (p-value = 0.0258).”
“The differences between the two vegetation types (CL and CR) were observed to be significant only around the peak of the season (i.e. summer; supplement 2).”
Which statistical tests did you perform? Please be more specific.
Page 9: Figure 4: Does transparency indicate whether the correlation is significant or not?
Page 11: Figure 6: What are the mean differences and RMSE between measured and modeled SIF? Please add more detailed statistical results to demonstrate their differences.
Page 11: The current Discussion section is too long. I would suggest separating Discussion and Conclusions sections to make it more clear.
Page 11: “Measured LAI has significant value only when we are estimating the properties of vascular plants, but for the over-all biomass and productivity analysis modeled LAI might be more important, as it includes biomass of vascular and non-vascular plants and hence it should be considered for peatlands.” This sentence is too long and hard to follow. Please rephrase it.
Author Response
Reviewer 3
To investigate the dynamic nature of peatland, this study uses the ground level remote sensing measurements and radiative transfer model SCOPE to retrieve and estimate several important vegetation indexes, such as LAI, SIF, NDVI, EVI and NIRv. The good correlation between measured and modeled SIF indicates that a reliable SIF value can be estimated through the SCOPE model for peatland vegetation, which is very useful when high-resolution hyperspectral measurement is not available. In general, this paper is well structured and easy to follow. However, I do believe that there is a need for extensive language edits and improvement.
Thank you, we carefully revised the manuscript for its language.
What are the uncertainties or weaknesses of the SCOPE model? Please add some discussion.
We provided the weaknesses of SCOPE in introduction, but more details can be found in a recent paper by co-authors (Yang, P.; Prikaziuk, E.; Verhoef, W.; van der Tol, C. SCOPE 2.0: a model to simulate vegetated land surface fluxes and satellite signals. Geoscientific Model Development. 2021, 14, 4697–4712, https://doi.org/10.5194/gmd-14-4697-2021)
Page 1: “But to have an understanding of satellite remote sensing there is need to have studies at the ground level.” Please rephrase the sentence.
Rephrased
Page 2: “These all phenomena lead to the dynamic behavior of peatland remote sensing signal which is different from the signals of the other ecosystems.” Please rephrase the sentence.
Rephrased
Page 2: “Even if the LAI is an important factor for ecosystem understanding its measurement/estimation is not easy, due to spatial and temporal heterogeneity.” Do you want to say measuring/estimating LAI is not easy?
Yes
Page 2: “Direct methods are the most accurate but tedious and time-consuming and can be destructive, whereas ground-based methods are based on radiation transmittance while remote sensing methods are based on reflectance.” This sentence is too long and hard to follow. Please rephrase it.
Rephrased
Page 3: I would recommend adding a map to mark the Pzecin peatland as well as CL and CR sites.
Added
Page 4: Table 1: Part of formula for EVI is missing.
Corrected
Page 6: “The modeled LAI obtained through the inversion of the SCOPE model showed a clear seasonal pattern, where the value of LAI started to go high with each measurement until it reaches its peak in July after that it tends to decrease towards its starting value for both the sites.” Please consider replacing “go high” with “increase”; removing “the” in the “both the sites”.
Corrected
Page 6: “There were no statistically significant differences among treatments for any day of measurement, except mod-eled LAI on 16th June for CR vegetation (Supplement 1) when LAI of W is significantly higher than LAI of C (p-value = 0.0258).”
“The differences between the two vegetation types (CL and CR) were observed to be significant only around the peak of the season (i.e. summer; supplement 2).”
Which statistical tests did you perform? Please be more specific.
A statistical section in material and methods provided
Page 9: Figure 4: Does transparency indicate whether the correlation is significant or not?
Yes, but the number indicates the same
Page 11: Figure 6: What are the mean differences and RMSE between measured and modeled SIF? Please add more detailed statistical results to demonstrate their differences
Provided
Page 11: The current Discussion section is too long. I would suggest separating Discussion and Conclusions sections to make it more clear.
The conclusion is added, whereas we tried to justify the discussion
Page 11: “Measured LAI has significant value only when we are estimating the properties of vascular plants, but for the over-all biomass and productivity analysis modeled LAI might be more important, as it includes biomass of vascular and non-vascular plants and hence it should be considered for peatlands.” This sentence is too long and hard to follow. Please rephrase it.
Rephrased
Round 2
Reviewer 1 Report
The authors have made efforts to address all of my comments. In the Introduction, I still think it's quite subjective to say that "... different types of vegetations (such 38 as bryophytes, pteridophytes, gymnosperms, and angiosperms) that coexist make the peatlands a complex system." In general, any ecosystem is "complex" in this sense. Further, I'm no sure that I agree with "Due to the distribution of peatlands in remote and waterlogged areas, the observation of peatland vegetation directly by personal surveys and measurements is very difficult and time-consuming." I'd suggest deleting "Due to the distribution of peatlands in remote and waterlogged areas." In any ecosystem, conducting detailed quantitative vegetation assessments is time-consuming - I don't think it is difficult, however. Perhaps a stronger argument here is that the development of remote sensing technologies and models may offer alternative approaches to vegetation assessment.
I'd still like to see a little more description of the site. Or something like see Górecki et al. (2021) for details on vegetation and water chemistry.
Author Response
An extensive English language correction was done in the manuscript.
In the Introduction, I still think it's quite subjective to say that "... different types of vegetations (such 38 as bryophytes, pteridophytes, gymnosperms, and angiosperms) that coexist make the peatlands a complex system." In general, any ecosystem is "complex" in this sense.
It is true that any natural ecosystem is complex, considering the coexistence of different plant groups. This sentence aimed to point on the complexity of the natural ecosystem as many remote sensing researchers work with monocultures of agricultural fields. However, the sentence is not crucial, and we are removing it to avoid controversies.
Further, I'm no sure that I agree with "Due to the distribution of peatlands in remote and waterlogged areas, the observation of peatland vegetation directly by personal surveys and measurements is very difficult and time-consuming." I'd suggest deleting "Due to the distribution of peatlands in remote and waterlogged areas." In any ecosystem, conducting detailed quantitative vegetation assessments is time-consuming - I don't think it is difficult, however. Perhaps a stronger argument here is that the development of remote sensing technologies and models may offer alternative approaches to vegetation assessment.
The mentioned part of the introduction was modified accordingly.
I'd still like to see a little more description of the site. Or something like see Górecki et al. (2021) for details on vegetation and water chemistry.
The reference towards Górecki et al., 2021 for details on vegetation and water chemistry was added.
Reviewer 2 Report
Your paper is very interesting.
Before publication, I would change:
in table 1, the reflectance sign for the 480 is missing;
the background color of Table 2 and the letter size should be the same as in Table 1.
Author Response
Your paper is very interesting.
Before publication, I would change:
in table 1, the reflectance sign for the 480 is missing;
the background color of Table 2 and the letter size should be the same as in Table 1.
Thank you for your careful revision with attention to details. Both issues were addressed in the submitted version of the manuscript.
