Light Transmissivity of Tree Shelters Interacts with Site Environment and Species Ecophysiology to Determine Outplanting Performance in Mediterranean Climates
Round 1
Reviewer 1 Report
This paper is very timely for landscape restoration endeavors, especially when dealing with a very challenging ecosystem with unfavorable climate and site conditions. The information on this paper can provide vital information about the use of ecotechnological tools in tree planting. The manuscript is well-written. I love the flow of the story and the manner how they present the results. However, I have a few concerns and suggestions below.
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Line/s |
Comments |
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15 |
Is it ‘herbivory’ or ‘hervibores’? |
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21 |
‘In general.’ Into ‘In general,’ |
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70-71 |
‘…deep root system allows plants to escape the desiccation of top soil layers during the after planting dry season [26],…’ please consider revising. Hard to understand. |
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92-95 |
These two sentences are a little bit hard to understand, please consider revising or make it simpler. |
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109 |
Remove the dangling word ‘selection’ at the end of the sentence. |
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Fig. 2 |
How did you derive the final height and root collar diameter? How did you address the biases or differences in height and RCD at the time of planting for each sample seedling? Did you use the relative growth rate per year? What would be the final unit? |
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369-378 |
Light, soil water, and temperature cannot be disentangled. When light is not limiting (summer) and temperature is high, soil water limitation will have a more profound effect on carbon gain and water loss (transpiration). However, when soil water is abundant coupled with optimum temperature, the light will become the most limiting factor. A study published in Forests Journal of MPDI on carbon gain/water loss effect during extreme soil water depletion periods discussed these climatic drivers on physiological mechanism in plant productivity and water use efficiency when soil water is limiting. You might get some insights from this paper: https://www.mdpi.com/1999-4907/10/1/14 |
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394-301 |
Maybe the authors can also explore the characteristics of the root system of both species. It might be that P. halepensis has a good root mechanism being able to explore deeper soil water despite soil moisture limitations (hydraulic lift) as discussed in another reference: DOI: 10.1111/j.1469-8137.2010.03245.x.
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Figure |
The authors used many bar graphs. Maybe they could explore using linear regressions to emphasize the relationships between transmissivity and important measured parameters to see how well they are correlated and to see the variance explained in the model. Then dig into the sources of variations between species or sites. |
Author Response
Light transmissivity of tree shelters interacts with site environment and species ecophysiology to determine outplanting performance in Mediterranean climates (LAND 1281552)
RESPONSE TO REVIEWERS SHEET
Reviewer 1
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Line/s |
Comments |
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15 |
Is it ‘herbivory’ or ‘hervibores’? RESPONSE: both things are correct. Herbivors action is herbivory |
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21 |
‘In general.’ Into ‘In general,’ RESPONSE: done |
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70-71 |
‘…deep root system allows plants to escape the desiccation of top soil layers during the after planting dry season [26],…’ please consider revising. Hard to understand. RESPONSE. Reworded, now reads: “. A deep root system allows plants to escape the desiccation of top soil layers that occurs during dry season [26],” |
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92-95 |
These two sentences are a little bit hard to understand, please consider revising or make it simpler. RESPONSE: we made it simpler: “Another important feature of tube shelter to understand its physiological effects is the inextricably relation between its transmissivity and air temperature [28]. It is well known the heating effect of tree shelters during daylight hours in this season. This effect becomes more intense in shelters with high transmissivities. Differences as high as 6ºC in mean temperatures in summer between clear tubes and open air have been detected [20,29].” |
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109 |
Remove the dangling word ‘selection’ at the end of the sentence. RESPONSE: done |
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Fig. 2 |
How did you derive the final height and root collar diameter? How did you address the biases or differences in height and RCD at the time of planting for each sample seedling? Did you use the relative growth rate per year? What would be the final unit? RESPONSE: final height is the sum of growth and initial (after planting) height. There is not potential bias because, at the time of planting, seedlings were randomly assigned to each treatment,. |
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369-378 |
Light, soil water, and temperature cannot be disentangled. When light is not limiting (summer) and temperature is high, soil water limitation will have a more profound effect on carbon gain and water loss (transpiration). However, when soil water is abundant coupled with optimum temperature, the light will become the most limiting factor. A study published in Forests Journal of MPDI on carbon gain/water loss effect during extreme soil water depletion periods discussed these climatic drivers on physiological mechanism in plant productivity and water use efficiency when soil water is limiting. You might get some insights from this paper: https://www.mdpi.com/1999-4907/10/1/14 RESPONSE: thanks a lot for this comment and suggestion. However, this paper deals with the response of a tropical rain forest ecosystem at a global scale to changes in seasonal variables using a flux tower. Our paper studies the response at individual seedling (juvenile stage) level within a Mediterranean ecosystem. Under these conditions, rooting depth and access to water is a key issue that is not addressed in the mentioned paper. |
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394-301 |
Maybe the authors can also explore the characteristics of the root system of both species. It might be that P. halepensis has a good root mechanism being able to explore deeper soil water despite soil moisture limitations (hydraulic lift) as discussed in another reference: DOI: 10.1111/j.1469-8137.2010.03245.x. RESPONSE: sorry but I’m not quite sure to what idea you refer to. L394-301 (401?) deals with physiological explanation for lack of growth response of Q. ilex to light transmission in arid plot. Anyway, thegood root mechanism of P halepensis is explained in L419 and beyond. |
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Figure |
The authors used many bar graphs. Maybe they could explore using linear regressions to emphasize the relationships between transmissivity and important measured parameters to see how well they are correlated and to see the variance explained in the model. Then dig into the sources of variations between species or sites. RESPONSE: thanks a lot for this interesting suggestion. However, in our experiment we have one treatment (Control=Mesh) that cannot be incorporated in a linear regression model of light transmissivity, because this treatment involves very different environmental conditions (direct versus diffuse radiation, greenhouse effect versus external air temperatures, etc). At the same time, Control treatment was necessary to confront the shelter effect versus no-shelter for both species. Moreover, even though we could compare responses within tube shelter treatments, they are not usually linear, so fitting linear regression could be problematic. Besides, light transmissivity is not a continuous variable in the experiment, so the value of a regression approach seemed limited to us. Therefore, we decided to consider transmissivity as a discrete variable in the analyses and discuss the results of these analyses according to the observed trends in response to transmissivity values. Hence the abundance of bar graphs that capture better the observed trends, in particular given the fact that transmissivity increases in equal intervals of 20%. |
Reviewer 2 Report
Oliet et al.’s manuscript presents nice and important results for Mediterranean afforestation. The manuscript is well-written, apart from some minor issues. The scientific background is clear, leading to testable hypotheses that are properly addressed. Results are presented and discussed appropriately.
Specific comments:
I have seen plastic tube shelters my whole life, but still needed a minute or two to understand what these are. A small picture would be nice, for the benefit of readers who are less familiar with the technique.
L 52, 56, 57 and onwards: The first mention of plastic tube shelters is as “tube shelters”, the second is as “tree-shelters”, and the thirds is “tube shelters”. Please be consistent in terminology, especially when dealing with the main term of this manuscript.
L 65-67: A sentence or two about the mechanism would be nice.
L 74-80: Shaded plants allocate more resources to shoot growth (to reach sunlight) and thus invest less in roots.
L 93-95: “During summer daylight hours, temperatures within the plastic tube shelter can be as much as 6 C above the ambient temperature outside it”
L 113: What is the ecology of each species?
L 132-133: “Alcazar de San Juan (39 … 640 m a.s.l.) is…”
Fig. 1: It would be nice to add a small map showing the location of sites (maybe over a Koppen map of Spain, if available). This can also be the right place for a small picture of a plastic tube shelter.
L 202: Does this mean that no roots were found below 70 cm?
Table 3: What are the colours?
Fig. 2-3: Are these the same as Tables 3-4? If so, keep the figures, delete Table 3, and move Table 4 to the supplementary information.
Author Response
Reviewer 2
Specific comments:
I have seen plastic tube shelters my whole life, but still needed a minute or two to understand what these are. A small picture would be nice, for the benefit of readers who are less familiar with the technique.
RESPONSE: a picture showing the four types (light transmissivities) of tree shelters has been included in Appendix
L 52, 56, 57 and onwards: The first mention of plastic tube shelters is as “tube shelters”, the second is as “tree-shelters”, and the thirds is “tube shelters”. Please be consistent in terminology, especially when dealing with the main term of this manuscript.
RESPONSE: for consistency, we have change every “tube shelter” by “tree shelter” along the text (including title). However we have kept the term “tube” when named alone to avoid reiteration and when referring to wall characteristics of the tube.
L 65-67: A sentence or two about the mechanism would be nice.
RESPONSE. Done. Now the sentence reads: Low light levels inside tube shelters elicit well-known physiological and morphological responses, like an increase in leaf specific area, stomatal density, and biomass allocation to shoots, and reduction of root growth [23]. These responses have been reported to decrease plant overall resistance to drought stress [24].
L 74-80: Shaded plants allocate more resources to shoot growth (to reach sunlight) and thus invest less in roots.
RESPONSE: I do not understand this comment. Anyway, at the beginning of this paragraph and in response to previous comment of this Reviewer, we have included the above sentence that describes the shade tolerance syndrome (Biomass allocation to roots)
L 93-95: “During summer daylight hours, temperatures within the plastic tube shelter can be as much as 6 C above the ambient temperature outside it”
RESPONSE: we have already reworded this sentence in response to Reviewer 1. Anyway we have removed “in this season” and incorporated “summer”
L 113: What is the ecology of each species?
RESPONSE: we mean the ecological characteristics of the habitats where the species thrive. They are explained in the following lines
L 132-133: “Alcazar de San Juan (39 … 640 m a.s.l.) is…”
RESPONSE: done
Fig. 1: It would be nice to add a small map showing the location of sites (maybe over a Koppen map of Spain, if available). This can also be the right place for a small picture of a plastic tube shelter.
RESPONSE: a picture showing the two site locations in Spain has been included in Appendix
L 202: Does this mean that no roots were found below 70 cm?
RESPONSE: we have added this sentence: “This depth is beyond subsoiling limits, where most new root tissues of planted seed-lings presumably thrive [26]. “
Table 3: What are the colours?
RESPONSE: colour removed
Fig. 2-3: Are these the same as Tables 3-4? If so, keep the figures, delete Table 3, and move Table 4 to the supplementary information.
RESPONSE: no, they are not the same. Table 3 is the annual growth in height and root collar diameter for first and second seasons; Table 4 is the ANOVA analysis for these results. Figure 2 includes the absolutes (final) height and root collar diameter at the end of second season; and Figure 3 depicts information about biomass. We decided to separate annual growth in height and RCD from final (absolute) growth because response of those magnitudes where different across both seasons (Table 3), while final height and RCD (Fig 2) gave the final picture of accumulated variables.
