the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 23 Jan 2025
Radial growth of Picea abies is controlled by joint effects of temperature and nutrient availability at the lower part of treeline ecotone
Abstract. Treeline ecotones in complex mountain landscapes are exposed to pronounced differences in irradiation and soil nutrient availability. Different amounts of nutrients and direct solar energy can influence tree stem growth resulting in variation of growth rates and growth phenology across lower parts of treeline ecotone. We hypothesized that at two contrasting sites located on north and south-facing slopes, differences in nutrient availability outperform temperature differences in modulating stem growth rates while growth phenology is driven by the course of seasonal temperature. To test this hypothesis, we compared the growth phenology and kinetics of Picea abies in the lower part of treeline ecotone between a north-facing slope with relatively nutrient-rich soils and a south-facing slope with nutrient-poor soils. We analysed intra-annual wood formation and its response to ambient climate, as well as soil and air microclimate and soil and needle nutrient content. Our results showed that thermal differences in treeline ecotones between south and north-facing slopes in temperate mountains are small but nontrivial involving higher daytime temperatures at south-facing slopes and longer irradiation of north-facing slopes during the middle part of growing season. The timing of growth onset and maximum growth rate were almost identical on both slopes. Accordingly, annual stem growth at both sites was most sensitive to the meteorological conditions at the start of the growing season and around the summer solstice. However, the absolute growth rate was higher on the north-facing slope, consistent with a higher availability and content of base cations in the soil and the needles. Our results suggest that temperature governs growth phenology at the lower part of the treeline ecotone, but nutrient availability modulates the growth rate in the peak season when temperature no longer limits cambial activity. We conclude that the effect of nutrient availability can be superior to the effect of slope aspect for stem growth rates of Picea abies located in the lower part of treeline ecotone in temperate mountain range.
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The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
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Preprint
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The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
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(319 KB) - BibTeX
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- Final revised paper
Journal article(s) based on this preprint
Interactive discussion
Status: closed
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RC1: 'Comment on egusphere-2025-151', Anonymous Referee #1, 22 Feb 2025
The study “Radial growth of Picea abies is controlled by joint effects of temperature and nutrient availability at the lower part of treeline ecotone” compared growth phenology of Picea abies tree growth at the opposite slope aspect (North-facing and South-facing) which are considered to have contrasting soil nutrient dynamics. The study claimed that temperature governs the growth phenology of these species, but ambiguously conclude that nutrient availability modulate the growth rate during the peak growing season. I partly agree with these conclusion due to following reasons:
- Since the study only considered single site at each slopes (N-facing and S-facing), the result cannot be generalized, particularly in the mountain landscapes with higher influence of microclimates. Please clarify these issues.
- There is no any statistical analysis to support the conclusion that soil nutrients drive/modulate their growth.
- Precipitation is considered to play a major role in soil formation and development and also tree growth (also mentioned in line 37-39), particularly in the alpine treeline ecotone. However, variation in precipitation between two study sites has not been mentioned. These sites may exhibit difference in precipitation (e.g. windward/leeward effects), which has been largely ignored. At least, soil moisture will be largely different between North-facing and South-facing slope aspects. There are more references on topography-dependent growth responses in the mountain regions. Please clarify.
- The authors mentioned that soil samples collected during two field campaign (2012-2014 and 2023) were merged to determine soil nutrients, which for me seems to be random.
- In my understanding, Picea abies as a dark forest species, and cannot survive in sunny and south-facing slope. Based on the landscape photo in Fig. 2, it may be not fully source facing slope (east-south or west-south), or the slope is strongly influenced by shade of surroundings, thus have a shade-like environment for spruce forest.
Other comments
In my opinion, there is no strong evidence to state that “Radial growth of Picea abies is controlled by joint effects of temperature and nutrient availability at the lower part of treeline ecotone”. Thus, the title seems to be more ambiguous.
Please clarify the term “lower part of treeline ecotone”. It is confusing to me. For the landscape photo, it is not clear whether there is climatic treeline or not in your research sites. It looks to be that trees almost cover the mountain top.
The hypotheses mentioned in abstract and introduction are different.
In the methodology section, it was mentioned that Kruskal-Wallis test was conducted to investigate the difference in measured soil variables between two sites. Did you find significant difference between sites? Why are their significance not included in the result section and figures? Not only for soil but also for all other variables.
Which chronology (standard?) was used for the climate-growth relationships? Also, please provide the statistics of the chronology, at least in the supplementary information.
Please check for Picea abies and make it consistent throughout the text (Italic).
There are many long sentences with a lot of repetition, which is difficult and tedious to follow. This issue should be carefully revised.
Based on line 97-99, Line 11 “…..contrasting sites located on north and south-facing slopes…..” is not true.
Line 254: I suggest not to use the phrase “it is worth mentioning……” here.
Line 289: may not be true.
Line 300: also see recent work:
Li, et al. 2023. National Science Review 10, nwad182, https://doi.org/10.1093/nsr/nwad182
Line 302-304, Long sentence with repetition.
Line 306: Clarify the term “systematically”
Line 311: Why are there no any references for nutrients?
Line 312-315 It is very difficult to follow.
Line 367. I suggest to delete “which lags behind the pace of warming”.
Citation: https://doi.org/10.5194/egusphere-2025-151-RC1 -
AC2: 'Reply on RC1', Vaclav Treml, 27 Mar 2025
Please find attached our replies to comments of the Reviewer 1.
As it is the first time I am dealing with editorial process in EGU journals we have directly prepared modified manuscript based on the reviews. Our answers therefore also contain references to lines of the manuscript where the change has been made.
On behalf of the authors,
Vaclav Treml
-
RC2: 'Comment on egusphere-2025-151', Anonymous Referee #2, 24 Feb 2025
The manuscript “Radial growth of Picea abies is controlled by join effects of temperature and nutrient availability at the lower part of treeline ecotone” by H. Kuželová et al. provides insights in the treeline ecotone dynamics linked to climate and soil nutrient availability. The authors were able to show that soil conditions can play a crucial role in influencing the radial growth of trees and mitigating the impact of solar radiation, which varies significantly in mountainous environments depending on the slope's exposure. Many studies in dendroecology do not consider soil variables (temperature, humidity, and nutrients), and this work stimulate to include these parameters to better understand growth dynamics at landscape and regional scales. Below comments and suggestions that could help to improve the manuscript.
Main comment 1:
The justification for selecting the lower part of the treeline for data collection in your experimental design remains unclear. In various sections of the manuscript, including the title, specific reference is made to “the lower part of the treeline ecotone”. The reasons your hypotheses are only applicable to trees within this elevation zone are not specified. The introduction should provide justification for choosing this specific area of the treeline and explain why it is more suitable for conducting the study.
Main comment 2:
The ring-width chronologies have not been sufficiently exploited in the study. Only the results of the correlations between climate and growth have been shown. There is a lack of basic statistics of the chronologies, such as average ring width (or average basal area increment), maximum and average age, serial intercorrelation, mean sensitivity etc. Average basal area increments can be better analysed by comparing the long growth series (100 years?) of the 60 samples taken from north and south sites rather than only the 16 trees (3 cambial years) sampled with Trephor.
Main comment 3:
The estimation of insolation on each site does not consider cloud cover. The discussions lack a section indicating the potential influence of this factor. The results of the correlations between climate and growth show a negative relationship with precipitation in the period DOY 115-125. This relationship is not discussed in the article. The relationship could be due to the negative effect of cloud cover (associated with precipitation), which makes photosynthetic activity less efficient at the beginning of the vegetative period.
Minor comments:
L 9-10: see main comment 1.
L14-16: Please rephrase this sentence.
L 78-79 & L 88: Species names in italic.
L 95-96: Is Picea abies the only tree species at the treeline?
Figure 1: Consider moving Figure 1C and 1D in the results section. You explain how you obtain this graph in M&M (ll 121-123).
L 119-120: Please specify if you consider continuous period or not.
l 136: Please specify if these six trees are the same sampled with Trephor.
L 193: “standardization”.
L 201&210: “°C” instead of “K”.
Table 1: Indicate the unit for degree days.
L294: See main comment 3. It's not clear what is meant by 'entire lifespan of trees' (2012-2014 period or 1961-2013 period?).Citation: https://doi.org/10.5194/egusphere-2025-151-RC2 -
AC1: 'Reply on RC2', Vaclav Treml, 27 Mar 2025
Please find attached our replies to comments of the Reviewer 2.
As it is the first time I am dealing with editorial process in EGU journals we have directly prepared modified manuscript based on the reviews. Our answers therefore also contain references to lines of the manuscript where the change has been made.
On behalf of the authors,
Vaclav Treml
-
AC1: 'Reply on RC2', Vaclav Treml, 27 Mar 2025
Interactive discussion
Status: closed
-
RC1: 'Comment on egusphere-2025-151', Anonymous Referee #1, 22 Feb 2025
The study “Radial growth of Picea abies is controlled by joint effects of temperature and nutrient availability at the lower part of treeline ecotone” compared growth phenology of Picea abies tree growth at the opposite slope aspect (North-facing and South-facing) which are considered to have contrasting soil nutrient dynamics. The study claimed that temperature governs the growth phenology of these species, but ambiguously conclude that nutrient availability modulate the growth rate during the peak growing season. I partly agree with these conclusion due to following reasons:
- Since the study only considered single site at each slopes (N-facing and S-facing), the result cannot be generalized, particularly in the mountain landscapes with higher influence of microclimates. Please clarify these issues.
- There is no any statistical analysis to support the conclusion that soil nutrients drive/modulate their growth.
- Precipitation is considered to play a major role in soil formation and development and also tree growth (also mentioned in line 37-39), particularly in the alpine treeline ecotone. However, variation in precipitation between two study sites has not been mentioned. These sites may exhibit difference in precipitation (e.g. windward/leeward effects), which has been largely ignored. At least, soil moisture will be largely different between North-facing and South-facing slope aspects. There are more references on topography-dependent growth responses in the mountain regions. Please clarify.
- The authors mentioned that soil samples collected during two field campaign (2012-2014 and 2023) were merged to determine soil nutrients, which for me seems to be random.
- In my understanding, Picea abies as a dark forest species, and cannot survive in sunny and south-facing slope. Based on the landscape photo in Fig. 2, it may be not fully source facing slope (east-south or west-south), or the slope is strongly influenced by shade of surroundings, thus have a shade-like environment for spruce forest.
Other comments
In my opinion, there is no strong evidence to state that “Radial growth of Picea abies is controlled by joint effects of temperature and nutrient availability at the lower part of treeline ecotone”. Thus, the title seems to be more ambiguous.
Please clarify the term “lower part of treeline ecotone”. It is confusing to me. For the landscape photo, it is not clear whether there is climatic treeline or not in your research sites. It looks to be that trees almost cover the mountain top.
The hypotheses mentioned in abstract and introduction are different.
In the methodology section, it was mentioned that Kruskal-Wallis test was conducted to investigate the difference in measured soil variables between two sites. Did you find significant difference between sites? Why are their significance not included in the result section and figures? Not only for soil but also for all other variables.
Which chronology (standard?) was used for the climate-growth relationships? Also, please provide the statistics of the chronology, at least in the supplementary information.
Please check for Picea abies and make it consistent throughout the text (Italic).
There are many long sentences with a lot of repetition, which is difficult and tedious to follow. This issue should be carefully revised.
Based on line 97-99, Line 11 “…..contrasting sites located on north and south-facing slopes…..” is not true.
Line 254: I suggest not to use the phrase “it is worth mentioning……” here.
Line 289: may not be true.
Line 300: also see recent work:
Li, et al. 2023. National Science Review 10, nwad182, https://doi.org/10.1093/nsr/nwad182
Line 302-304, Long sentence with repetition.
Line 306: Clarify the term “systematically”
Line 311: Why are there no any references for nutrients?
Line 312-315 It is very difficult to follow.
Line 367. I suggest to delete “which lags behind the pace of warming”.
Citation: https://doi.org/10.5194/egusphere-2025-151-RC1 -
AC2: 'Reply on RC1', Vaclav Treml, 27 Mar 2025
Please find attached our replies to comments of the Reviewer 1.
As it is the first time I am dealing with editorial process in EGU journals we have directly prepared modified manuscript based on the reviews. Our answers therefore also contain references to lines of the manuscript where the change has been made.
On behalf of the authors,
Vaclav Treml
-
RC2: 'Comment on egusphere-2025-151', Anonymous Referee #2, 24 Feb 2025
The manuscript “Radial growth of Picea abies is controlled by join effects of temperature and nutrient availability at the lower part of treeline ecotone” by H. Kuželová et al. provides insights in the treeline ecotone dynamics linked to climate and soil nutrient availability. The authors were able to show that soil conditions can play a crucial role in influencing the radial growth of trees and mitigating the impact of solar radiation, which varies significantly in mountainous environments depending on the slope's exposure. Many studies in dendroecology do not consider soil variables (temperature, humidity, and nutrients), and this work stimulate to include these parameters to better understand growth dynamics at landscape and regional scales. Below comments and suggestions that could help to improve the manuscript.
Main comment 1:
The justification for selecting the lower part of the treeline for data collection in your experimental design remains unclear. In various sections of the manuscript, including the title, specific reference is made to “the lower part of the treeline ecotone”. The reasons your hypotheses are only applicable to trees within this elevation zone are not specified. The introduction should provide justification for choosing this specific area of the treeline and explain why it is more suitable for conducting the study.
Main comment 2:
The ring-width chronologies have not been sufficiently exploited in the study. Only the results of the correlations between climate and growth have been shown. There is a lack of basic statistics of the chronologies, such as average ring width (or average basal area increment), maximum and average age, serial intercorrelation, mean sensitivity etc. Average basal area increments can be better analysed by comparing the long growth series (100 years?) of the 60 samples taken from north and south sites rather than only the 16 trees (3 cambial years) sampled with Trephor.
Main comment 3:
The estimation of insolation on each site does not consider cloud cover. The discussions lack a section indicating the potential influence of this factor. The results of the correlations between climate and growth show a negative relationship with precipitation in the period DOY 115-125. This relationship is not discussed in the article. The relationship could be due to the negative effect of cloud cover (associated with precipitation), which makes photosynthetic activity less efficient at the beginning of the vegetative period.
Minor comments:
L 9-10: see main comment 1.
L14-16: Please rephrase this sentence.
L 78-79 & L 88: Species names in italic.
L 95-96: Is Picea abies the only tree species at the treeline?
Figure 1: Consider moving Figure 1C and 1D in the results section. You explain how you obtain this graph in M&M (ll 121-123).
L 119-120: Please specify if you consider continuous period or not.
l 136: Please specify if these six trees are the same sampled with Trephor.
L 193: “standardization”.
L 201&210: “°C” instead of “K”.
Table 1: Indicate the unit for degree days.
L294: See main comment 3. It's not clear what is meant by 'entire lifespan of trees' (2012-2014 period or 1961-2013 period?).Citation: https://doi.org/10.5194/egusphere-2025-151-RC2 -
AC1: 'Reply on RC2', Vaclav Treml, 27 Mar 2025
Please find attached our replies to comments of the Reviewer 2.
As it is the first time I am dealing with editorial process in EGU journals we have directly prepared modified manuscript based on the reviews. Our answers therefore also contain references to lines of the manuscript where the change has been made.
On behalf of the authors,
Vaclav Treml
-
AC1: 'Reply on RC2', Vaclav Treml, 27 Mar 2025
Peer review completion
Journal article(s) based on this preprint
Data sets
Data and scripts associated with the manuscript “Radial growth of Picea abies is controlled by joint effects of temperature and nutrient availability at the lower part of treeline ecotone” H. Kuzelova et al. https://doi.org/10.5281/zenodo.14619874
Data and scripts associated with the manuscript “Radial growth of Picea abies is controlled by joint effects of temperature and nutrient availability at the lower part of treeline ecotone” H. Kuzelova et al. https://doi.org/10.5281/zenodo.14619874
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Hana Kuzelova
Tomas Chuman
Jelena Lange
Jan Tumajer
Vaclav Treml
The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
- Preprint
(936 KB) - Metadata XML
-
Supplement
(319 KB) - BibTeX
- EndNote
- Final revised paper