The Value of Hybrid Aspen Coppice Investment under Different Discount Rate, Price and Management Scenarios: A Case Study of Estonia

Round 1

Reviewer 1 Report

The issue addressed in the paper discusses the value of hybrid aspen coppice investment. The leading problem was analysed based on price volatility and expected rate of return under different management scenarios. The authors proposed an important and interesting topic, compatible with the scope of the journal.

Such studies are partially analysed in literature. It would be worth presenting the state of the art in a broader way. I suggest a more dilligent, comparative description of other scientific research from the literature. State of the art is cursory (very general, only partially related to the topic of the study)  and - in my opinion - insufficient.

I recommend a few corrections to improve the quality of this article:

- to precisely define the research scenario (it is very general); needed to clarify the scope of the study and consequently a clear, step-by-step, simple, synthetic research pattern; yes, the methodology is described, but I recommend more precision, as the reader should know how to repeat a similar analysis on this basis (please consistently correct and complete section 2);

- to improve the readability and description of tables (3,4), and figure 2 (since they are the basis for analysis verification), supplement the history of their description, a clear and not laconic reference in the paper); please explain clearly how the regression model was constructed.

- to explain briefly whether there is  need to use, for instance, other methods;

that is, supplement the summary descriptive analysis. Does the conclusion answer all the questions posed at the beginning of the paper (expressed in objectives and hypotheses)? Please complete it and also correct it. The conclusion needs to be supplemented.

I also strongly suggest that recommendations for specific, practical, not only general (and not entirely clear) applications of this research shall be provided (please complete point 4). Please assess whether, however, the verified hypotheses are not too general - and it is difficult to justify the entitlement to their practical verification (more in it suppositions / visions, dreams - than economic, empirical and useful recommendations).

The language of this paper is relatively correct, however some descriptions would benefit from being more concise. I recommend that the authors work with a native speaker to improve the text (language) of the paper.

Author Response

Response to Reviewer 1 Comments

 Point 1: Such studies are partially analysed in literature. It would be worth presenting the state of the art in a broader way. I suggest a more dilligent, comparative description of other scientific research from the literature. State of the art is cursory (very general, only partially related to the topic of the study)  and - in my opinion - insufficient.

Response 1: to the best of our knowledge, this study is the first estimation of the profitability of different thinning and management alternatives for the second-generation hybrid aspen stands in Northern Europe. Early corridor thinning treatments and intensive biomass coppicing systems with aspen have not been compared from economic perspective in published research articles. There are only a few recent economic studies in Northern Europe about early thinning in deciduous forests (e.g. Witzell et al 2019; Bergström et al 2014; Dahlgren Lidman et al 2021; Jylhä et al 2015; Di Fulvio et al 2011), which we had also cited. Much more literature on economics of such short-rotation forestry systems is available from more southerly regions of Europe and other parts of the World, but those studies are not good reference to us because of different forest growth conditions (much higher yields and shorter rotations in the south) as well as different specialties of regional wood markets, hence we did not include those studies to our ms. Forest management in Northern Europe has mainly focused on conifer species (Norway spruce and Scots pine) managed with long rotations but the interest in deciduous species and short-rotation plantation forestry has grown during the recent decades (driven by climate changes, biodiversity conservation needs in old forests, forest industry developments etc.), but the respective economic studies are scarce. Therefore, the main reasons for our study were that hybrid aspen short-rotation systems are new to the region and the experience how to manage them in economically best way is insufficient.

 

Point 2: I recommend a few corrections to improve the quality of this article:

- to precisely define the research scenario (it is very general); needed to clarify the scope of the study and consequently a clear, step-by-step, simple, synthetic research pattern; yes, the methodology is described, but I recommend more precision, as the reader should know how to repeat a similar analysis on this basis (please consistently correct and complete section 2);

Response 2: we have implemented the methods in the revised ms following also comments made by Reviewers 2 and 3.

 

Point 3: - to improve the readability and description of tables (3,4), and figure 2 (since they are the basis for analysis verification), supplement the history of their description, a clear and not laconic reference in the paper); please explain clearly how the regression model was constructed.

Response 3: We have provided more details and original source (Kiviste et al. 2002) for the used models and improved the description of the sources of data presented in Tables 3 and 4 in the revised ms. We added the reference Hepner et al 2020 to guide the reader to the detailed description of the thinning trial. The operation costs data was obtained from the State Forest Management Centre (the largest forest owner and manager in Estonia) based on personal communication, we have highlighted this now more clearly. We included in the revised ms that the average operation prices in Estonia were used (due to relatively small size of Estonia, processing prices do not vary considerably).

 

Point 4: - to explain briefly whether there is  need to use, for instance, other methods;

that is, supplement the summary descriptive analysis. Does the conclusion answer all the questions posed at the beginning of the paper (expressed in objectives and hypotheses)? Please complete it and also correct it. The conclusion needs to be supplemented.

Response 4: we added in the revised Discussion two new paragraphs describing potential limitations of our study, as recommended also by the Reviewers 2 and 3. In the new text we also added some new aspects (e.g. climate change mitigation potential) on how to evaluate these alternative management scenarios.

 

Point 5: I also strongly suggest that recommendations for specific, practical, not only general (and not entirely clear) applications of this research shall be provided (please complete point 4). Please assess whether, however, the verified hypotheses are not too general - and it is difficult to justify the entitlement to their practical verification (more in it suppositions / visions, dreams - than economic, empirical and useful recommendations).

Response 5: We have now implemented discussion with also some practical suggestions for choosing the best management scenario for these stands. However, as we had written in the original Discussion, all of the compared scenarios have their strengths and weaknesses and the final choice depends on investor’s expectations. On the other hand, our study relies partly on modelled yield data (except for the empirically estimated yield of 5-yr energy wood coppicing scenario and starting points for growth modelling for the 25-yr rotation scenarios), hence we did not intend to be over-speculative or test more specific hypotheses.

 

Point 6: The language of this paper is relatively correct, however some descriptions would benefit from being more concise. I recommend that the authors work with a native speaker to improve the text (language) of the paper.

Response 6: As the Reviewers have evaluated that “English language and style are fine/minor spell check required” we will rely on the authors’ instructions of Forests, which state that “All accepted manuscripts undergo language editing”.

Reviewer 2 Report

Dear Authors,

Please find the comments in the attached file.

Regards

Comments for author File: Comments.pdf

Author Response

Response to Reviewer 2 Comments

Point 1: This study looks like a case study, if so name it

Response 1: We agree with the Reviewer and we have revised the title as follows:

The value of hybrid aspen coppice investment under different discount rate, price and management scenarios: a case study of Estonia

 

Point 2: This part belongs to methods

Response 2: We agree. As this information was already given in the Methods, we decided to remove the mentioned paragraph from the revises ms.

 

Point 3: The initial dencity reduction by 97% it is a lot. Please check these figures or if so please provide more information regarding number of planted trees and number of trees remaining after thinning

Response 3: The second-rotation hybrid aspen stand is not planted. It raised vegetatively from root and stump suckers after clear-cutting of the planted stand. After the first year, we counted the average number of stems: 94 000 trees/ha (Hepner et al 2020). The stand density reduction by 97% results in ca 2800 trees/ha, which is comparable to common forest planting density in Estonia. For better clarity we have provided the initial density in the revised ms.

 

Point 4: inform about its moisture, is it fresh or oven dried biomass?

Response 4: It is oven-dried biomass, we added this specification in the revised ms.

 

Point 5: Please provide the source for the model, or its evaluation, in figure 1 it does not look very reliable.

Response 5: The significance of the model is presented in Table 2 and it was <0.05. Therefore, we can consider the model reliable. We added the source of the model function (Kiviste et al 2002) to the revised ms.

Reference: Kiviste, A., Alvarez Gonzales, J.G., Rojo Alboreca, A., Ruiz Gonzales, A.D., 2002. Funciones de crecimiento de aplocacion en el ambito forestal. Madrid: Instituto Nacional de Investigacion y Tecnologia Agraria y Alimentaria Ministerio de Ciencia y Tecno. 195 pp.

 

Point 6: quadratic mean diameter?

Response 6: Thank You for pointing this out. Indeed, its quadratic mean diameter. We revised the ms accordingly.

 

Point 7: I would sugest to present this model in the manuscript. Dont make the raeader to go and search for the model. It is much better then all important parts are in one place

Response 7: We added the model to the revised ms.

 

Point 8: source needed

Response 8: We added a reference in the revised ms.

Straka, T.; Bullard, S.H. The land expectation value calculated in timberland valuation. Appraisal Journal, 1996, 64, 399 – 405.

 

Point 9: I think it would be a good idea to provide standing volumes and total yield for all scenarios at age of 25 years.

Response 9: We have added these values in text boxes in Figure 3 in the revised ms.

 

Point 10: Please discuss the limitations or the weak sides of your findings. How your results are sensitive to selected timber prices or labour costs? Which management alternative would be the best taking present and future economic situation in Estonia. Are your results applicable in other countries?

Response 10: We improved the discussion in the revised ms according to the Reviewer’s suggestions. We have added two paragraphs in the end of Discussion to address these matters.

 

Point 11: Your study needs a conclusions part. If these are your conclusions please name them appropriately

Response 11: We added paragraph „Conclusions“ to the revised ms.

Reviewer 3 Report

This paper attempts to assess the economic feasibility of different management strategies of  hybrid aspen coppice stands, by applying forest thinning scenarios. Overall, I think that the manuscript is interesting and may contribute to the implementation of more profitable forest management alternatives. Still, some improvements are needed for the paper to achieve a higher scientific value.

The authors should explain the methodological procedure a little bit better. Particularly, could authors provide more details about the data introduced into analysis? Which is the source of the data?

Line 253-254: The authors mention that “the Energy-wood coppicing strategy is clearly the only one providing positive gains for an investor in case of non-extreme price developments”. Please provide some additional details to support this finding.

Please articulate the novelty and the significance of the paper in a clearer way.

Additionally, I think that the paper would greatly benefit from adding a conclusion section, where authors could present the key points of their survey.

 

Author Response

Response to Reviewer 3 Comments

Point 1: The authors should explain the methodological procedure a little bit better. Particularly, could authors provide more details about the data introduced into analysis? Which is the source of the data?

Response 1: We improved the methodology section by adding some additional formulas to the revised ms (as suggested by the Reviewer1). In addition, we improved the description of the thinning methods. Paragraph “2.1 Forest management strategies for hybrid aspen coppice stands” describes the source data with the reference to Hepner et al 2020. The input data for the growth modelling and economic calculations of the present study comes from the empirical data collected from the thinning experiment in Estonia. The early growth data was published by Hepner et al 2020, including schematic explanation of the experiment.

 

Point 2: Line 253-254: The authors mention that “the Energy-wood coppicing strategy is clearly the only one providing positive gains for an investor in case of non-extreme price developments”. Please provide some additional details to support this finding.

Response 2: We thank the Reviewer about the remark. For the clarity, we added an explanation in the revised ms that this result is only in the case of LEVs with 20% discount rate.

 

Point 3: Please articulate the novelty and the significance of the paper in a clearer way.

Response 3: The novelty of the study: The economic feasibility of different management strategies of hybrid aspen coppice stands has not yet been comprehensively evaluated in Northern Europe. Its already mentioned in the abstract (lines 15-16). In addition, we mentioned in the Introduction that the profitability of coppicing followed by different thinning treatments has not been comprehensively evaluated (lines 87-89). We highlighted the novelty of the study in the first sentence of  “Conclusion” paragraph in the revised ms.

 

Point 4: Additionally, I think that the paper would greatly benefit from adding a conclusion section, where authors could present the key points of their survey.

Response 4: Thank You for the suggestion. We added a conclusion section to the revised ms.