Teak Tree-Ring Cellulose δ¹³C, δ¹⁸O, and Tree-Ring Width from Northwestern Thailand Capture Different Aspects of Asian Monsoon Variability

Reviewer1

response

Unfortunately, the paper cannot be recommended for publication in Atmosphere in its current form. Scientific aspects proposed here would be worth being propagated, but some oversights in the proposed manuscript preclude such a verdict. Especially the definition of d13C correction is wrong.There is no information about physiological processes affecting d13C and d18O.

Thanks for the advice,

We have updated it as follows.

δ¹³C_corr = (δ¹³C_air-δ¹³C)/ (1+δ¹³C)/1000))

Where δ¹³C_corr and δ¹³C represent corrected and raw tree-ring δ¹³C, respectively. We used published values of δ¹³C_air for the period 1901–2003 from McCarroll and Loader (2004), and extrapolated the near-linear decline of δ¹³C_air over the last decades to estimate the values for 2004–2009. Please see line 175-179

Lines 100 – 104 Can be found: ”We selected 4 teak cores from 4 teak trees with the following selection criteria 1) the specimen is very old, 2) the tree-ring boundaries are visible, 3) the annual ring is not very  narrow, and 4) the age determination is correct. All four samples, cross-correlation were checked again using the COFECHA, to ensure that the re-collected samples matched each other well.” What can be said about the population signal for selected trees?

We have proven that the sample numbers have passed benchmark statistics by analyzing EPS and Rbar (Wigley et al. 1984).  Please see like 209-211

Lines 140-157 It would be useful to standardise the description of how the measurements were carried out in the two laboratories. For d¹⁸O measurement there is no indication of measurement standards. What was the furnace temperature for these measurements?

Thank for your consideration.

We extracted alpha cellulose and oxygen isotope analysis at the Institute of Geography, University of Erlangen-Nuremberg, Erlangen, Germany. At the State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi’an, China, we took the alpha cellulose we analyzed from the German lab for carbon isotope analysis, so no standardization is required.

We have added more details to oxygen isotope analysis.

The cellulose samples were converted to CO at 1,450° C by using an elemental analyzer (EA, HT Oxygen Analyzer, Thermo Fisher, Germany) linked to an isotope ratio mass spectrometer (Delta V Advantage, Thermo Fisher, Germany). The ratios of 18O /16O were measured with respect to the VSMOW standard (Vienna Standard Mean Ocean Water) with an analytical precision of ±0.3‰ and expressed as δ18O. The δ18O values were referred to the International Standard (Vienna Standard Marine Ocean Water: VSMOW): δ¹⁸O = [(R_sample/R_standard) - 1] x 1,000, where R_sample and R_standard are the 18O/16O ratios of the sample and standard, respectively).  Please see line 142-150

The formula for isotopic delta concerns only carbon isotopes, no reference is made to oxygen isotopes.

We have added more details to oxygen isotope analysis. Please see line 175-179

Line 164 - The formula is incorrect.

We have updated it.

δ¹³C_corr = (δ¹³C_air-δ¹³C)/ (1+δ¹³C)/1000))

Where δ¹³Ccorr and δ¹³C represent corrected and raw tree-ring δ¹³C, respectively. Please see line 175-179

“A logical standard value is the ‘pre-industrial’ d13C of the atmosphere, for which -6,4 % is a reasonable estimate. This is close to values around AD 1850 and also prior to the Little Ice Age (Francey et al., 1999). The values that need to be added in order to quote industrial tree-ring d13C values relativeto pre-industrial atmospheric d13C  are also presented in Table 2” (McCarroll, 2004).

Correction values (‰) for each year should be added to the corresponding tree ring d13C value.

Thank you very much.

We have updated it.

Table 2 is invisible

I'm sorry, it must have happened while the file was being sent. But I've added a table. Please see table 2

The discussion lacked an analysis of the correlation between d13C and  d18O including physiological processes (no analysis of information on stomatal conductance and assimilation rate).

I have further discussed the relationship between the two isotopes and tree physiology such as “Our results are consistent with the conceptual model of [52], who proposed a positive correlation of δ¹⁸O_TR and δ¹³C_TR, concluding that these isotopes were associated with the stomatal conductance response, while photosynthesis had no effect.” Please see line 432-435

Information on the temporal stability of the climatic signal is also missing. Is this signal as clear for the period of increased human activity as for the early years?

Thank you for your question. Although our three teak indices cover approximately 100 years and we did not analyze the moving correlation of the three indexes to the climate data. But we do expect that the relationship between the three indexes and climate will change over time because, according to climate data in Mae Hong Son Province, rainfall, temperature and relative humidity have fluctuated over 70 years.

Reviewer2

Article is focused on very interesting area of the climate – tree interaction research. O Is base on the modern methods and brings interesting results.  The form and structure is adequate . Used methodological apparatus  and statistical procedures are acceptable and modern.  Maybe the deeper interpretation   related to the tree –environment interaction will increase the article value.

Thank you very much for your advice and guidance.

Page 6: L Legend to the chapter 3,2, - mistake – the ratio of C is written twice

Thank you very much, we have fixed it.

Table 2 is empty 

We are sorry for the mistake, but we have added Table 2 to the revised version. Please see table 2