Projected decrease in wintertime bearing capacity on different forest and soil types in Finland under a warming climate

Lehtonen, Ilari; Venäläinen, Ari; Kämäräinen, Matti; Asikainen, Antti; Laitila, Juha; Anttila, Perttu; Peltola, Heli

doi:https://doi.org/10.5194/hess-23-1611-2019

Articles | Volume 23, issue 3

https://doi.org/10.5194/hess-23-1611-2019

© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/hess-23-1611-2019

© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 23, issue 3

Research article

|

19 Mar 2019

Research article |

| 19 Mar 2019

Projected decrease in wintertime bearing capacity on different forest and soil types in Finland under a warming climate

Ilari Lehtonen, Ari Venäläinen, Matti Kämäräinen, Antti Asikainen, Juha Laitila, Perttu Anttila, and Heli Peltola

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Final revised paper (published on 19 Mar 2019)
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Preprint (discussion started on 19 Jan 2018)
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Interactive discussion

Status: closed

AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment

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RC1: 'Review', Anonymous Referee #1, 02 Mar 2018
- AC1: 'Reply to referee #1', Ilari Lehtonen, 27 Apr 2018
RC2: 'hess-2017-727-RC2', Anonymous Referee #2, 31 Mar 2018
- AC2: 'Reply to referee #2', Ilari Lehtonen, 27 Apr 2018

Peer-review completion

AR: Author's response | RR: Referee report | ED: Editor decision

ED: Reconsider after major revisions (further review by editor and referees) (04 Jun 2018) by Patricia Saco

AR by Ilari Lehtonen on behalf of the Authors (06 Jul 2018) Author's response Manuscript

ED: Referee Nomination & Report Request started (25 Jul 2018) by Patricia Saco

RR by Anonymous Referee #2 (27 Aug 2018)

RR by Anonymous Referee #3 (10 Oct 2018)

Suggestions for revision or reasons for rejection

Overall assessment
I believe that the study is interesting and of potential interest to the readers of HESS. However, though the manuscript has improved during the revision process, there are still significant issues that need to be addressed. My main concern is the poor description of the methodology, which is of particular interest to the audience of this journal. I find the description of the methodology quite confusing and lacking important information as described in more detail below. Some aspects of the results and discussion are also not clearly explained (details also below), which is at times aggravated by poor English usage.
Detailed comments linked to text
The authors refer to “model optimization” throughout the manuscript (starting with the abstract). They are indeed optimizing parameters but with the goal of “calibrating” the model. So this should be clear in the abstract and throughout the manuscript, because within our community model optimization often refers to a very different aim (optimizing water allocation, etc); while here the use of optimization is very clearly focussed on calibration.
Sections 2.1, 2.2.2, etc.: titles for these subsections: It would be clearer to use the term “description” rather than “outline”.
Section 2.1.2: Unfortunately, the description in this section is vague and unclear.
Page 5, Line 9, include the soil types for “Lompolojänkkä and Kaamanen ”.
Page 5, line 10-12: “measurements needed in the calculations were not available from Lettosuo, Lompolojänkkä and Kaamanen stations”, the next lines mention that nearby stations are used, but it is not clear what stations.
Page 5, Lines 13-30: “the optimal parameter values were set to each station and each available measurement depth.” This sentence is unclear. Do you mean that you calibrated the parameters for each station at different depths? What parameters were “calibrated”? It seems that you include the parameters used in the calibration in Table 2, but you should mention them in the text, with a justification of why are these parameters selected (are you calibrating all possible parameters?). You also need to justify the selected parameters ranges for calibration. Are you using a Monte Carlo approach? Please include a description of the calibration approach, with more technical details, with a more rigorous technical language as this will be easier to follow. For example :
lines 10-20 state: “For some parameters optimized values varied rather randomly within the sampling range between different depths and locations while, for example, KT seemed to steadily increase with soil depth, assumedly largely due to increasing soil moisture with increasing depth”
The calibration procedure needs to be described with more rigour, it is unclear what the behaviour of each parameter was... “some parameters varied randomly” which parameters? Why?
Line 21: “Zl was set to 6.8 m and fS to 9.0 at each location and depth” why these values?
Line 23: “after this second optimization round, all other parameters except KT were also set to their final values.” What do you mean by “final values”?
Lines 23-24: “KT,LOW and CS,LOW were given the same values at all depths and locations while CICE was set to depend on the soil type and CS the depth following asymmetrical sigmoid function.” There is no rationale on why this was done.
Line 25: It seems that in the end only Ks is calibrated?
Line 26: “Anjala, Sodankylä and Lettosuo stations were selected to represent clay/silt, sand and peat soil types, respectively” At what point in the calibration was this decided? Why? Shouldn’t this be decide at the beginning?
Lines 27-34: The rest of this section is also unclear.
Page 6, Section 2.1.3. Please clarify the procedure used here. The authors state:
Lines 2-5: “Apart from the stations used in calibration of KT for different soil types (Lettosuo, Anjala and Sodankylä), the modelled soil temperatures for clay/silt and sand soil types typically explained 90–99% of the observed variability in soil temperatures between the depths of 20 and 100 cm (Table S2).”
This sentence is unclear. You mention “apart from the stations” this suggests that you are going to use data from “other stations”?
Lines 5-6: “In spite of the generally high correlations, the modelled number of days with soil temperatures below 0 °C were still greatly overestimated, even by more than twofold on many stations.”
Where are you showing this? Please refer to the table/figure explicitly.
Page 7. Line 14. You are probably referring to the next section not chapter.
Page 10. Lines 11-14 states: “The calculations for the period 1980–2099 under changing climate were completed using daily data from six GCMs (listed in Table S4) participating in the CMIP5 (Taylor et al., 2012; Flato et al., 2013), as bias-corrected and downscaled onto the Finnish grid”. Please clarify: Table S4 does not contain much information. What are the variables/data that are being used? What is the “bias-correction” (note that you mention this later in some figures without any explanation. What is the downscaling? Please add a brief explanation, and if needed more info.
Page 11. Section 3.1: Figure 2 is discussed in section 3.1. It presents the results of the model on number of days with satisfactory bearing capacity for 1981-2010, which are compared to observations. Lines 14-19 state: “the used models generally reproduce the spatial pattern of wintertime bearing season length during the baseline period as expected as the model data has been bias-correct”. I am not sure what patterns are discussed here. The comparison of results from GCM/RCM to those using observation do not show a “general good agreement”. I would argue that the agreement is very poor. The patterns based on observation show a gradual trend from southern to northern portions that is absent from the ones produced by the ensemble forecasts, these last ones have a more random pattern. Please clarify. Please also explain the potential impact of this lack of agreement on the projected trends for climate change.
Page 11. Section 3.2: Lines 25-26 is unclear. It is also not explained why the focus has already shifted to drained peatlands as opposed to the other soils. The discussion should focus on all soil types for this figure.

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ED: Publish subject to revisions (further review by editor and referees) (09 Nov 2018) by Patricia Saco

AR by Ilari Lehtonen on behalf of the Authors (19 Dec 2018) Author's response Manuscript

ED: Referee Nomination & Report Request started (02 Jan 2019) by Patricia Saco

RR by Anonymous Referee #2 (03 Feb 2019)

RR by Anonymous Referee #3 (15 Feb 2019)

ED: Publish as is (03 Mar 2019) by Patricia Saco

AR by Ilari Lehtonen on behalf of the Authors (04 Mar 2019)

Short summary

Wintertime bearing capacity on different forest soils with respect to timber harvesting in the projected future climate of Finland was estimated by using a soil temperature model and a wide set of downscaled climate model simulations. The results indicate that, particularly, drained peatlands may virtually lack soil frost over large areas in most of winters during the late 21st century. There is thus a clear need to develop new sustainable and efficient logging practices for peatland forests.