Treeline-Quo Vadis? An Ecophysiological Approach
Round 1
Reviewer 1 Report
Summary: In this manuscript, the authors aim to review the literature on changes to treelines due to climate change and land use. The authors suggest a definition of the tree line as the limit of up-right trees with a minimum height of 2-3m, explicitly excluding krummholz, which consists of non-upright trees of lower height. Based on the literature, the authors describe recent changes to the alpine tree line. They find that individual trees have increased growth in recent decades only at low density. They conclude that while the ecophysiological limits change with climate warming, land use changes are equally important for the future of treelines. The paper is generally well prepared; however, the language should be revised for grammar, and simplicity and clarity. For example, the use of “life-form tree” is confusing and the term should be defined once at the beginning. The distinction between “tree” and “krummholz” is clear and can be used without any potential for confusion after an initial definition. This literature review does contain data (Figure 2). However, the sample is very limited (only 6 trees from 1 site), the methods are not explained, and no statistical test was conducted.
Additional points:
- Line 27: for the treeline…?
- Line 28: Comma missing
- Line 29: rephrase “may keep alive”
- Line 33: to?
- Line 33: rephrase “climatic driven treeline”
- Line 34: physiological limits of trees?
- Line 36: rephrase “following on treeline structure”
- Line 46: Meaning unclear: “well coupled to the atmosphere”
- Line 47: Deformed implies some kind of external cause, however, often seed from krummholz trees will form krummholz phenotypes in any environment.
- Line 48: Here, this is ignoring ecotype
- Line 53: Remove “low”
- Line 53: The table provides a definition for “tree”, remove “life form tree” here and elsewhere for brevity and clarity.
- Line 61-62: Meaning of sentence unclear.
- Line 66: What global examination?
- Line 73-74: First part of sentence, meaning unclear. Please rephrase.
- Line 76: Is tree architecture the right term here? Shading of the roots is also influenced by density. Please provide reference for this statement.
- Line 89: Please provide better illustrations of the two categories. Beside differences in scale, the both tree lines look diffuse.
- Line 121: On individual tree growth
- Line 121: dot missing.
- Line 123: Please provide additional references supporting this result, 6 trees from 1 site are insufficient to make this point.
- Line 129: at the treeline?
- Line 136: is invading the correct term?
- Line 137: Rephrase favors
- Line 142: Rephrase sentence.
- Line 143: What is the reference for the second part of the sentence?
- Line 150: Increases instead of enhances
- Line 160: Yes, but effects might also compound.
Author Response
Dear reviewer,
thank you vey much for your detailed comments on this paper. Please find below our comments on your suggestions:
Summary: In this manuscript, the authors aim to review the literature on changes to treelines due to climate change and land use. The authors suggest a definition of the tree line as the limit of up-right trees with a minimum height of 2-3m, explicitly excluding krummholz, which consists of non-upright trees of lower height. Based on the literature, the authors describe recent changes to the alpine tree line. They find that individual trees have increased growth in recent decades only at low density. They conclude that while the ecophysiological limits change with climate warming, land use changes are equally important for the future of treelines. The paper is generally well prepared; however, the language should be revised for grammar, and simplicity and clarity. For example, the use of “life-form tree” is confusing and the term should be defined once at the beginning. The distinction between “tree” and “krummholz” is clear and can be used without any potential for confusion after an initial definition. This literature review does contain data (Figure 2). However, the sample is very limited (only 6 trees from 1 site), the methods are not explained, and no statistical test was conducted.
- The term life-form tree is now defined in Table 1 of the revised manuscript (see also response to additional point line 53).
- The term krummkolz is also initially defined (see also response to additional point line 47 and line 48).
- With respect to Figure 2 pleas see our response to additional point line 123).
Additional points:
Line 27: for the treeline…?
As recommended we inserted “the” before treeline. See line 27 in the revised version.
Line 28: Comma missing
We inserted the comma. See line28 in the revised version
Line 29: rephrase “may keep alive”
We rephrased as recommended. See line 29 in the revised manuscript.
Line 33: to?
We corrected. See line 33 in the revised version.
Line 33: rephrase “climatic driven treeline”
Line 34: physiological limits of trees?
As suggested we rephrased this part. See line 33 - 36 in the revised version.
Line 36: rephrase “following on treeline structure”
We rephrased as suggested. See line 38 - 40 in the revised version.
Line 46: Meaning unclear: “well coupled to the atmosphere”
For clearness we reworded this “terminus”. See line 48 - 99 in the revised version.
Line 47: Deformed implies some kind of external cause, however, often seed from krummholz trees will form krummholz phenotypes in any environment.
and
Line 48: Here, this is ignoring ecotype
We now state that term krummholz designates environmentally dwarfed foms of tree specimem that become upright at favourable sites, the term scrub should only be applied to those treeline specimem, whose shrubby form is of genetic origin. See line51 – 54 as well Table1 in the revised manuscript.
Line 53: Remove “low”
We did as recommended. See line 60 in the revised manuscript.
Line 53: The table provides a definition for “tree”, remove “life form tree” here and elsewhere for brevity and clarity.
As the expression “life-form tree” is well established in plant ecophysiological treeline research (see pares by Körner, Hoch and others) we decided stay with this expression, which now is also defined in Table 1 in the revised manuscript.
Line 61-62: Meaning of sentence unclear.
For clarification we reworded this sentence. See line 68 – 70 in the revised manuscript.
Line 66: What global examination?
We changed examination to survey. See line75 in the revised manuscript.
Line 73-74: First part of sentence, meaning unclear. Please rephrase.
For clarification we rephrased this sentence. See line 83 – 85 in the revised manuscript,
Line 76: Is tree architecture the right term here? Shading of the roots is also influenced by density. Please provide reference for this statement.
Yes in our opinion tree architecture the right term here, because this holds also for isolated trees at treeline. We now also provide references. See line 86 – 88 in the revised manuscript.
Line 89: Please provide better illustrations of the two categories. Beside differences in scale, the both tree lines look diffuse.
We did as recommended. See new Fig 1
Line 121: On individual tree growth
We corrected as recommended. See line134 in the revised manuscript.
Line 121: dot missing.
We inserted the missing dot. See line134 in the revised manuscript
Line 123: Please provide additional references supporting this result, 6 trees from 1 site are insufficient to make this point.
With respect to Fig. 2 we agree that 6 trees from one site are a limited sample. Anyway, in line 128 of the revised version we now state that these data are originated from a case study. Furthermore, in the revised version of the legend to Fig. 2(see line 136 -143 in the revised version) we now provide details to the used methods and statistics of this preliminary case study. References underpinning our results are provided in line132 - 134 and line 144 – 150 of the revised version
Line 129: at the treeline?
At treeline is correct. See line 146 of the revised manuscript.
Line 136: is invading the correct term?
According to references 38,,52, 53, 54 and 55 invading is the correct term in line 154 of the revised manuscript.
Line 137: Rephrase favors
As recommended we rephrased. See line 155 in the revised version.
Line 142: Rephrase sentence.
We rephrased as recommended.. See line 160 – 161 in the revised version
Line 143: What is the reference for the second part of the sentence?
The References for the second part of the sentence are provided in line 162 of the revised version.
Line 150: Increases instead of enhances
We corrected accordingly. See Line 169 in the revised version.
Line 160: Yes, but effects might also compound.
For sure, thus, we now consider dryness as a factor counteracting a warming induces growth enhancement and treeline advancement. See line 181 – 183 in the revised manuscript.
Reviewer 2 Report
Dear authors,
I enjoyed reading your paper. I think that readers can learn a lot from this opinion paper concerning the treeline, its structure and dynamics. The manuscript is well-written and logically structured. I have only some minor comments and suggestions which you may find below.
Lines 13-14: This is something that has been done in the scope of the current paper, so I would prefer to see present instead of future tense.
Keywords: There is no need to use “treeline” as a keyword since it already appears in the title
Line 29: “keep alive” could be replaced by “provoke”
Line 35: “Krummholz” sounds rather German. Maybe you can also give the definition here (presented in Table 1). The readers may not be familiar with the term.
Line 32: “according to reference” can be deleted and the reference can go at the end of the sentence.
Line 33: replace “do” with “to”
Lines 36-37: “Moreover, following on treeline structure, the 36 focus will be on”. Consider revising. Future tense can be replaced by present.
Line 48: first “and” could be omitted
Table 1 is very useful, but its format needs to be checked.
Line 100: delete , after belt
Line 109: Do you mean that treelines do not respond similarly to climate warming at global scale? Some revision I think is needed here to make it clear.
Line 110: “weakness of the evaluation by reference”. Unclear meaning. Consider revising
Line 114: “some cases” sounds rather vague. Maybe you could give some examples
Figure 2: Why do not you give the same scale? Add location of the Mt. Patscherkofel, so as for the figure caption to be self-explicit.
Line 128: replace “is also known” with “are also known”
Line 132: replace “is” with “are”
Line 135: You are giving the full name for Alnus alnobetula. You should do the same for Pinus cembra and Larix decidua in line 118.
Line 160: You may also consider the ecological complex of dryness stands against a treeline advance.
Author Response
Dear reviewer,
thank you vey much for your detailed comments on this paper. Please find below our comments on your suggestions:
Lines 13-14: This is something that has been done in the scope of the current paper, so I would prefer to see present instead of future tense.
As suggested we changed to present. See line14 in the revised manuscript.
Keywords: There is no need to use “treeline” as a keyword since it already appears in the title
We deleted “Treeline” in keywords. See line 16 in the revised manuscript.
Line 29: “keep alive” could be replaced by “provoke”
We replaced accordingly: See line29 in the revised manuscript.
Line 35: “Krummholz” sounds rather German. Maybe you can also give the definition here (presented in Table 1). The readers may not be familiar with the term.
In line 32- 33 of the revised version we now give the definition for krummholz in brackets.
Line 32: “according to reference” can be deleted and the reference can go at the end of the sentence.
As recommended we deleted “according to reference” and set the reference number at the end of the sentence. See line 33 and 34 of the revised manuscript.
Line 33: replace “do” with “to”
We replaced accordingly. See line 33 in the revised manuscript.
Lines 36-37: “Moreover, following on treeline structure, the 36 focus will be on”. Consider revising. Future tense can be replaced by present.
As recommended, we considered revising and replaced future tense by present. See line 38 – 40 in the revised manuscript.
Line 48: first “and” could be omitted
We completely revised this sentence. See line 55 -57 in the revised manuscript.
Table 1 is very useful, but its format needs to be checked.
We checked and corrected the format of Table 1 in the revised version.
Line 100: delete , after belt
We did so. See line 111 in the revised manuscript.
Line 109: Do you mean that treelines do not respond similarly to climate warming at global scale? Some revision I think is needed here to make it clear.
and
Line 110: “weakness of the evaluation by reference”. Unclear meaning. Consider revising
As recommended, for clarification we revised this part. See line120 -122 in the revised version of the manuscript.
Line 114: “some cases” sounds rather vague. Maybe you could give some examples
For clarification we now reworded this section. See line 124 -127 in the revised manuscript. Examples are given in References 34, 37 and 38 (as it was also in the former version of the manuscript.
Figure 2: Why do not you give the same scale? Add location of the Mt. Patscherkofel, so as for the figure caption to be self-explicit.
In the revised version we now give the same scale and added the location in the Figure caption.
Line 128: replace “is also known” with “are also known”
We replaced accordingly. See line 145 in the revised version.
Line 132: replace “is” with “are”
We replaced accordingly. See line 149 in the revised version.
Line 135: You are giving the full name for Alnus alnobetula. You should do the same for Pinus cembra and Larix decidua in line 118.
As recommended, we now give the full name for Pinus cembra and Larix decidua. See line 130 and 131 in the revised manuscript.
Line 160: You may also consider the ecological complex of dryness stands against a treeline advance.
As recommended, we now consider dryness as a factor counteracting a warming induces growth enhancement and treeline advancement. See line 181 – 183 in the revised manuscript.
Reviewer 3 Report
This manuscript discussed the future treeline developments with respect to climate change, competition and land use changes. This information is very useful and the paper is well presented. I only have a few comments as follows.
1) The annual temperature data could be added to Figure 2.
2) Whether the Latin name of tree species includes the designated person, the full text needs to be unified.
Author Response
Dear reviewer,
as recommended we took all your suggestions into account (in Figure 2 temperature data were added; species names included).
Round 2
Reviewer 1 Report
Figure 2: Please add the statistical test used. Using alpha=0.1 for small sample sizes is questionable. Instead of using letters to indicate significance, displaying the actual p-values would provide more transparency.
Author Response
As recommended, we now indicate the P values in Fig. 2
