Final decision on bg-2015-347

Title: “Time since death and decay rate constants of Norway spruce and European larch deadwood in subalpine forests determined using dendrochronology and radiocarbon dating”

Authors: M. Petrillo, P. Cherubini, G. Fravolini, J. Ascher, M. Schärer, H.-A. Synal, D. Bertoldi, F. Camin, R. Larcher, and M. Egli


Dear Dr. Egli,

both reviewers provided a detailed and substantial evaluation of bg-2015-347. The reviewers highlight the scientific importance of the presented dataset and, however, indicate that there is potential to improve the scientific quality especially in the material and method section, analysis and interpretation of the obtained results.

After reading all comments. critics and suggestions of both reviewers, the short comments and your author’s responses and how you will address the indicated suggestions in the revised version of the manuscript, I am pleased to accept your manuscript for publication in Biogeosciences after a major revision considering the following remarks:

Reviewer 1 indicates to present more information on the sampling sites and wood composition (see also comments of Reviewer 2 considering the sampling of cores from living trees). Reviewer 1 also mentions that larch trees were mainly sampled at the south-facing sites while spruce was mainly sampled at the north-facing sites which is important to consider in the discussion.

Regarding the cellulose and lignin data, Reviewer 1 argues that the methods for their analysis is described in this manuscript while the results refer to already published data (Petrillo et al. 2015). Please clarify this.

Reviewer 1 claims on the comparison of the wood decay with decomposition of soil organic matter. He states that there are totally different processes and factors involved in the decomposition of soil organic matter that influences the degradation or preservation of its compounds. This should be better addressed in the discussion of a revised version of the manuscript.

Both short comments of Dr. T. Kahl and Dr. V.-A. Angers indicate that you should better acknowledge possible sampling biases which might explain the low decay rates (especially of larch which has a relatively low number of analyzed samples). As you indicated in your response, this issue will be focused in a revised version of this manuscript. V.-A. Angers also indicates that the discussion would be improved if the influence of species-specific snag fall rates were acknowledged. However, I suggest that the authors should be cautious in the discussion as fall rates of snags of the both studied trees are not known for the study region and any further discussion is based on many assumptions.

Major concerns of Reviewer 2 indicate that you should explain and also discuss more in detail the differences of the living tree-ring chronologies of both species presenting differences in their sensitivity (even if this is not the main focus of this study).

Another point raised by Reviewer 2 is the number of deadwood samples from larch trees (in the material and method section you indicate 12 collected deadwood samples from larch, while Tables 5, 6 and A1 indicate a larger number of analyzed samples.

Reviewer 2 also indicates that a comparison of the year of death indicated by cross-dating with the period of dead obtained by radiocarbon dating should be performed if these data are available to show if both dating techniques come up with the same result. In the case of differences this should be discussed (dating errors of both techniques).

Furthermore the influence of temperature and precipitation of the decay rates of coarse wood could be better addressed in the statistical analysis as those vary considerably along the altitudinal gradient of about 800m between the sampled sites.

A critical point is also the radiocarbon dating which has for most samples of the decay classes 4 and 5 a relatively low probability of 50-60% and wide variation of calibrated ages due to the Suess-effect which complicates dating wood samples in the period from 1640 to 1950. This should be considered more in detail in the revised version of this manuscript.

The number of tables in the manuscript is quite large and should be reduced as the few data of tables 3 and 4 are also indicated in the text.

Please indicate how you addressed the reviewer comments and short comments in your revised manuscript in a response letter.

Best regards,

Jochen Schongart
(Associated Editor of Biogeoscences)

Final decision on bg-2015-347

Title: Time since death and decay rate constants of Norway spruce and European larch deadwood in subalpine forests determined using dendrochronology and radiocarbon dating

Authors: M. Petrillo, P. Cherubini, G. Fravolini, M. Marchetti, J. Ascher, M. Schärer, H.-A. Synal, D. Bertoldi, F. Camin, R. Larcher, and M. Egli

Dear Prof. Egli,

your revised manuscript of bg-2015-347 sufficiently addresses the critics and suggestions of the two reviewers and two readers (T. Kahl and V.-A. Angers) as you indicated in the detailed author’s response. The incorporation of these in the revised manuscript and the additional performed analyses have substantially improved the manuscript bg-2015-347. The revised version includes now detailed information on sampling and analyses and critically discusses the problems of CWD age overestimation and radiocarbon dating. Therefore I consider bg-2015-347 for publication in Biogeosciences after some technical corrections. Thank you for choosing Biogeosciences for publication and my apologies for the delay in the review process.

Technical corrections:

P. 5 / L. 102: As you already indicated the abbreviation of coarse wood debris at the begin of the introduction there is no need to indicate it again.

P. 7 / L. 159-160: I think the correct term is master chronology, not master (dendro)chronology.

P. 8. / L. 179: I suggest to indicate the reference of Wigley et al. (1984).

P. 10 / L. 238: Add a space between “Karst.” and “and”. You can also delete the author’s name of the two species and indicate the initials of the genera as this information was already provided in the introduction.

P. 17 / L. 403: insert “was” before “based”.

P. 17 / L. 418-420: As you refer to “some other studies”, I suggest to cite here more than one study.

P. 18 / L. 436 and L. 447: The abbreviation "Fig." should be used when it appears in running text and should be followed by a number unless it comes at the beginning of a sentence.

Fig. 5/Fig. 7/Tables 3 & 4: units in the denominator should be formatted with negative exponents (g cm-3).

Tables 5 & 6: substitute yr-1 by y-1.