Potential of a Light Combined Harvester/Forwarder to Reduce Wildfire Risk in Mediterranean Forests: Comparison with Current Work System
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThe article deals with actual topic connected to forest fires prevention. I consider it to be up-to-date and bringing new insights on the topic. In my opinion, it is more beneficial for operational practice than from a scientific point of view.
I have the following comments on it:
For Figures 4 and 5, I recommend to the authors to state that the sum of the % for individual plots is 100 for both harvester and forwarder combined.
Table 9 - Description should be on the same page as the table. The abbreviations used in the table (A1 - 4, WP1 - WP 4) should be explained.
Author Response
COMMENT: For Figures 4 and 5, I recommend to the authors to state that the sum of the % for individual plots is 100 for both harvester and forwarder combined.
RESPONSE: Thanks for the comment, we completely overlooked this detail. We added a note in the caption of both figures.
COMMENT: Table 9 - Description should be on the same page as the table. The abbreviations used in the table (A1 - 4, WP1 - WP 4) should be explained.
RESPONSE: The abbreviations used in the table had been inserted in Material and Method section.
Reviewer 2 Report
Comments and Suggestions for AuthorsThe risk of forest fires in the Mediterranean basin is potentially very high. This is influenced by relatively high temperatures largely related to climate change. It is clear that this risk is also related to the specifics of each forest stand (species composition, tree density, growing stock). Therefore, it is important to properly manage such areas, including the form of clearing or thinning.
The article presented for review fits into these issues. In general, it was written correctly. It contains all the necessary chapters. Statistical analysis is also not objectionable. Before publishing it, the following suggestions should be taken into account:
- The resolution of the photos should be improved.
- Lines 165-167. Please clarify what the data related to stand damage bring about the subject? Does it affect the possibility of fires?
- Lines 176-179. The subsection is too short. Please expand it or eliminate it.
- Table 4. Why only 150 days of machine use per year (1200/8) were assumed. Repair cost ratio - on what basis was the quantity of this ratio adopted? For harvesters it is usually in the range of 80 to 120%. What does Agricultural fuel mean - is it biodiesel?
- If possible, please separate Results from Discussion.
- Figure 5. Forwarder in the description write please with a lowercase letter.
- Please compare the achieved labor productivity results with the average results presented for several countries in the publication “Timber Harvesting Methods in Eastern European Countries: a Review” (CROJFE).
- Figure 6. Description of the y-axis. The abbreviation „s” is used rather for time. In this case if there is a reference to a tree it should be changed.
- Figure 7. The lines do not correspond to the legend, where continuous lines are presented. Please eliminate also one dot at the description of the figure.
- In Conclusions the second paragraph should be eliminated as it is a description of the research conducted. Conclusions should refer directly to the results achieved.
Author Response
COMMENT: The resolution of the photos should be improved.
RESPONSE: High quality photos have been uploaded on the Forests Submission Portal for their inclusion in the final manuscript.
COMMENT: Lines 165-167. Please clarify what the data related to stand damage bring about the subject? Does it affect the possibility of fires?
RESPONSE: The data related to stand damage provide essential information regarding the quality of the thinning operation and its implications for wildfire risk reduction. Reduced damage to residual trees ensures better overall stand health, which is a key factor in enhancing forest resilience against fires. Specifically, minimizing wounds on the remaining trees reduces the likelihood of pathogen entry and branch desiccation, both of which could increase the availability of dry fuel and, consequently, the risk of ignition and fire spread. Furthermore, the lower incidence of ground disturbance and bark damage in mechanized operations, as highlighted in our results, contributes to preserving soil structure and maintaining ground cover. We added a section in the introduction with these considerations (lines 97-99)
COMMENT: Lines 176-179. The subsection is too short. Please expand it or eliminate it.
RESPONSE: the subsection has been integrated with further details and the time requested by the operation. We consider that this section is very relevant as it describes an operation that is unique for this type of Combo machines and enables more work flexibility and lower relocation costs.
COMMENT: Table 4. Why only 150 days of machine use per year (1200/8) were assumed. Repair cost ratio - on what basis was the quantity of this ratio adopted? For harvesters it is usually in the range of 80 to 120%. What does Agricultural fuel mean - is it biodiesel?
RESPONSE: Thank you for your thoughtful questions. Regarding the machine use, the assumption of 150 days of machine use per year is based on typical working conditions for preventive silviculture operations in Mediterranean forests. These activities are often constrained by seasonal weather conditions, fire risk periods, and regulatory restrictions, which limit the number of operational days annually. Additionally, the machine's deployment is influenced by the availability of public subsidies and the mosaic-like forest ownership structure, leading to irregular work schedules.
The repair cost ratio of 70% was adopted considering the specific context of the study, where the machine operates in dense, post-fire regenerated stands with challenging conditions for maneuverability. These factors result in relatively high wear and maintenance costs. While we acknowledge that repair costs for harvesters typically range between 80% and 120%, the lighter nature of the Malwa 560C and its combined harvester/forwarder design justify a lower ratio. Similar values have been reported in studies on small-scale equipment used in early thinning operations.
In this context, "agricultural fuel" refers to a type of diesel commonly used in forestry and agricultural machinery, which benefits from reduced taxation in some regions. It is not biodiesel but rather a standard diesel fuel with a different tax rate applied to machines used in primary production activities. This aligns with local practices in Catalonia, where preventive silviculture is considered part of forest management activities eligible for agricultural fuel taxation rates. A note has been added to the table
COMMENT: If possible, please separate Results from Discussion.
RESPONSE: We separated the two sections.
COMMENT: Figure 5. Forwarder in the description write please with a lowercase letter.
RESPONSE: We have corrected it.
COMMENT: Please compare the achieved labor productivity results with the average results presented for several countries in the publication “Timber Harvesting Methods in Eastern European Countries: a Review” (CROJFE).
RESPONSE Thanks for the suggestion, we added the reference in line 458.
COMMENT: Figure 6. Description of the y-axis. The abbreviation „s” is used rather for time. In this case if there is a reference to a tree it should be changed.
RESPONSE: Yes, the abbreviation "s" is used for seconds referring to the Productivity of felling and processing, the legend below the Figure might cause confusion. We changed that. The figure is now number 5 as a previous figure has been moved to discussion.
COMMENT: Figure 7. The lines do not correspond to the legend, where continuous lines are presented. Please eliminate also one dot at the description of the figure.
RESPONSE: Thanks for the correction, indeed it was wrong! We added dotted lines in the legend and eliminated the dot in excess in the caption.
COMMENT: In Conclusions the second paragraph should be eliminated as it is a description of the research conducted. Conclusions should refer directly to the results achieved.
RESPONSE: We eliminated this paragraph as suggested.
Reviewer 3 Report
Comments and Suggestions for AuthorsReview
Forest fires have been a significant and growing problem for most countries in the world in recent decades. The increase in their occurrence and intensity is certainly associated with global climate change, where increasing ambient temperature, lack of precipitation and the occurrence of strong winds accelerate forest fires. The authors of the presented article deal with this issue in the Mediterranean region, for which forest fires are a traditionally occurring harmful phenomenon with very negative consequences. In their article, the authors analyze possible preventive measures limiting the occurrence and development of forest fires, propose a way to solve them using forestry logging technologies and assess the possibility of making them more effective compared to traditional manual methods of removing woody biomass, which can be a source of fuel for forest fires. The topic of the article is therefore very topical and beneficial both for the scientific sphere and, in particular, for the potential use of the results presented in the article in forestry practice.
I express my opinion on the individual parts of the article as follows:
The abstract presents the most important findings of the submitted article in a concise and understandable form. It justifies the importance of forestry measures for mitigating the risk of forest fires. It emphasizes that the tried and tested highly mechanized method of removing woody biomass is more advantageous under certain conditions than the current manual technology. I have no comments on the abstract.
Chapter 1 – Introduction presents a relatively wide range of information on the importance of forest fires, their causes and forestry measures that can mitigate the risk of forest fires. As one of them, the authors mention the removal of unnecessary woody plants by thinning. They also deal with the circumstances and factors associated with these activities. In my opinion, the chapter is written very well, it presents all the essential information (including the influence of the vegetation density factor on forest fires), and also states the basic objectives of the research study on which the text of the article is based, and therefore I have no comments or questions about it.
Chapter 2 – Materials and Methods first introduces the area in subsection 2.1 where the research observations were made. It is clear that this is an area with a relatively acute risk of forest fires – it is therefore correctly chosen for the given purpose. The authors carried out their observations in three experimental plots with different densities of forest stands of local pine. This allowed them to analyze the effect of stand density on the economic indicators of thinning carried out manually and using highly mechanized logging technology with a combined harvester/forwarder Malwa 560C Combi. In subsection 2.2 the parameters of this combined machine are characterized. It is clear that this machine (a harvester/forwarder, also known as a forwester) was chosen appropriately for the given purpose. The following subsections 2.3 to 2.7 describe in considerable detail the individual steps of the research investigation, including a description of field trials, data collection and individual steps (tasks) performed during thinning on the Malwa 560C Combi combined machine. The cost analysis is very carefully described in subsection 2.8. Subsection 2.9 briefly and clearly describes the statistical analysis method used. Overall, I conclude that Chapter 2 is written in a comprehensible manner, contains almost all the necessary information and its content demonstrates that the authors used appropriate and modern methodological procedures. I would recommend that the authors add a brief description of the existing manual thinning technology to Chapter 2, with which they compared the new highly mechanized technology. I have no further comments on Chapter 2.
Chapter 3 Results and Discussion first presents in subsection 3.1 the result of a time study of the work of the combined machine Malwa 560C Combi, first when used as a harvester (Fig. 3) and then as a forwarder (Fig. 5). Subsection 3.1 presents, among other things, the difference in the time required for the machine to work depending on the density of the forest stand (plots 1, 2, 3). The following subsection 3.2 assesses the productivity of a box plot per square meter per tree on individual plots. It is clear that this synthetic quantity also depends on the density of trees on individual plots. The next subsection 3.3 deals with the analysis of the costs associated with activities on individual plots. Here too, the influence of tree density on the costs incurred during thinning is clearly visible. Subsection 3.4 is significant, which presents the calculation of the costs that would be incurred for the same activities when using the classic manual pruning method. I consider it very positive that the authors did not only deal with technical and economic indicators in their study, but also evaluated the cultivation result of the farm (subchapter 3.5). Thanks to this, their research is comprehensive. Overall, I would summarize my opinion on chapter 3 as follows: the findings presented here correspond to the research intention, provide evidence of the dependence of working time consumption on thinning depending on the density of stands and document better results of the combined machine Malwa 560C Combi on plots 1 and 2 compared to classic manual motor technology. The results were obtained by measuring at three locations, so they probably cannot be completely generalized for the entire Mediterranean region, but the basic opinion on the usefulness of the new technology with the help of the machine Malwa 560C Combi can undoubtedly be obtained from the text of the article. However, I miss the Discussion section announced in the title in this chapter - I therefore recommend adding a Discussion section, both the polemics of the "authors with themselves" and the results of other authors.
Last chapter no. 6 – The conclusion briefly and concisely summarizes the results presented in the previous parts of the article. I have no reservations about this.
Author Response
COMMENT I would recommend that the authors add a brief description of the existing manual thinning technology to Chapter 2, with which they compared the new highly mechanized technology. I have no further comments on Chapter 2.
RESPONSE: Thanks for the detailed analysis and the fruitful comments. The manual working method is described in Chapter 3.4 (lines 365-375). Since we did not time record the manual system (figures were provided by the company) we prefer not to describe it in Chapter 2 where we describe in detail the work system object of time studies and product measurement.
COMMENT: Chapted 3: However, I miss the Discussion section announced in the title in this chapter - I therefore recommend adding a Discussion section, both the polemics of the "authors with themselves" and the results of other authors.
RESPONSE: Thanks for the suggestion, we separated the two sections in Results and Discussion chapters.
Reviewer 4 Report
Comments and Suggestions for AuthorsThis manuscript primarily investigates the potential of using a light combined harvester/forwarder (Malwa 560C Combi) to reduce wildfire risk in Mediterranean forests, and compares its performance with the current manual work system. The study was conducted in the Catalonia region of Spain, where three pine forest plots at different stages of development were selected, representing high, medium, and low tree densities. The article provides a detailed description of the study area, the machinery used, the experimental design, data collection methods, cost analysis, and statistical analysis techniques.
There are a few points for improvement that deserve attention.
- The manuscript presenteda statistical analysis of the potential for using lightweight combine harvesters/transport aircraft to reduce wildfire risks, but lacks theoretical research. It is recommended to strengthen theoretical research by improving the performance of lightweight combine harvesters/transport aircraft themselves and optimizing operational procedures.
- The study was conducted only in specific pine forests in the Mediterranean region, and cannot comprehensively reflect the situation in other types of forests or geographical areas. It is suggested to expand the research scope to include different types of forests and geographical regions.
- The study only tested and analyzed one model of lightweight combine harvester/transport aircraft, and compared it with traditional operational methods. It is recommended to increase comparative analysis research with other combine harvesters/transport aircraft.
- There are some formatting irregularities in the article, such as capitalization issues with the first letter of words on line 103 and punctuation issues on line 354. It is suggested to carefully proofread the entire text to improve formatting consistency.
Author Response
COMMENT: The manuscript presenteda statistical analysis of the potential for using lightweight combine harvesters/transport aircraft to reduce wildfire risks, but lacks theoretical research. It is recommended to strengthen theoretical research by improving the performance of lightweight combine harvesters/transport aircraft themselves and optimizing operational procedures.
RESPONSE: Thanks for your valuable comments. We think there is a typo error in the comment, probably due to the automatic text corrector: the study focuses on a professional combined forest harvester/forwarder, no transport aircraft is involved. Focusing on the specific comment, we do not understand completely the reference to theoretical research, and we apologize for this. Previous bibliography in thinning operations and machinery has been analyzed and described in introduction and compared in discussion. The principles of a correct wildfire-resilient forest management had been also considered, although this is not an exact science and depends on a plethora of uncontrolled factors: in principle it is commonly accepted that an overall fuel load reduction and the elimination of ladder fuels plays a crucial role in reducing risk and intensity of wildfires.
COMMENT: The study was conducted only in specific pine forests in the Mediterranean region, and cannot comprehensively reflect the situation in other types of forests or geographical areas. It is suggested to expand the research scope to include different types of forests and geographical regions.
RESPONSE: Thanks for the suggestion. In this specific case we focused on pine forests as these are the most relevant type of forest in the Mediterranean areas of the Iberic peninsula, besides being the most challenging in terms of wildfire risk. Performing this test with an innovative machine, not present in the Mediterranean forestry, has requested a considerable investment possible only in the frame of an EU project. As suggested, future research will expand the scope of this manuscript to other forest types, geographical regions deploying the same or a different type of innovative equipment.
COMMENT: The study only tested and analyzed one model of lightweight combine harvester/transport aircraft, and compared it with traditional operational methods. It is recommended to increase comparative analysis research with other combine harvesters/transport aircraft.
RESPONSE: Thanks for the comment, as stated in the previous response, we demonstrated an innovative machine for the local scenario. Clearly, this is just an example and several other equipment would be interesting to be tested in the same scenario or a different type of forest. This will be object of future publications.
COMMENT: There are some formatting irregularities in the article, such as capitalization issues with the first letter of words on line 103 and punctuation issues on line 354. It is suggested to carefully proofread the entire text to improve formatting consistency.
RESPONSE: Thank you for your comment, the issues you identified have been solved.
Round 2
Reviewer 4 Report
Comments and Suggestions for AuthorsNot sufficiently modified.
Author Response
1) At the starting of the "study area" there is a mistake in the reference number;
RESPONSE: Thanks you for identifying the mistake. We corrected the reference
2) In the text pay attention to the line spacing it is not the same in all the text;
RESPONSE: We homogenized the line spacing in all the text.
3) some measurement units are wrong, for example: Lt is not correct only l; PMH15-1, pay attentio to the apex and subscript, 15 is subscript but -1 must be apex of PMH not of 15.
RESPONSE: We have corrected the unit of measurement from "lt" to "l." As for PMH15-1, we have verified that in Word, the formatting already has 15 as subscript and -1 as superscript for PMH although it does indeed seem that -1 is a superscript of 15.
4) Discussion, the sub chapter 4.5 needs for more discussion and comparison with other scientific papers.
RESPONSE: We integrated the sub chapter 4.5 with more discussion and comparison with other scientific papers.
