Effects of Clonal Integration on Foraging Behavior of Three Clonal Plants in Heterogeneous Soil Environments
Round 1
Reviewer 1 Report
The manuscript is very well written and organized. The general organization is excellent. It´s quality is near to be published. I have only some questions/recommendations:
1) What consisted the high- and low-nutrient soil used in the study? I suggest you to put a table with the soil carachterization. Depending on this variations, you can have varying results! You should discuss it at the end.
2) Please check the text in the parentheses on line 15 (to allow clonal integration from the mother ramet); I think it should be: (to avoid clonal integration from the mother ramet).
3) On line 150 please check the therm "blue"; it should be "red"
Author Response
The work seems scientifically sound and provides interesting and sometimes unexpected results about foraging responses of three vegetatively propagating herbal plants.
Reply: Thank you.
Several notes for the authors to consider:
In the introduction, the authors claim that there are very few publications that assessed clonal integration and foraging responses of clonal plants simultaneously (page 2, lines 55-57); however the references to these few publications, if they are known to the authors, are not given.
Reply: As far as we know, no study has tested clonal integration and foraging response simultaneously. We thus have changed the text to “to our best knowledge, none has assessed them simultaneously” (line 57 in the revised manuscript).
Maybe a sentence or two, linking the topic of the article to forests, would be helpful (simply to justify the choice of a journal).
Reply: We have added a sentence to show that the study species occur at forest margins and/or forest understories (line 93-95).
In line 72 (page 2), I guess there should be "to prevent clonal integration" rather than "to allow", because "to allow" is again in line 73.
Reply: Thanks for pointing out this error. It should be “to prevent clonal integration”. We have corrected this error .
Reviewer 2 Report
The work seems scientifically sound and provides interesting and sometimes unexpected results about foraging responses of three vegetatively propagating herbal plants.
Several notes for the authors to consider:
In the introduction, the authors claim that there are very few publications that assessed clonal integration and foraging responses of clonal plants simultaneously (page 2, lines 55-57); however the references to these few publications, if they are known to the authors, are not given.
Maybe a sentence or two, linking the topic of the article to forests, would be helpful (simply to justify the choice of a journal).
In line 72 (page 2), I guess there should be "to prevent clonal integration" rather than "to allow", because "to allow" is again in line 73.
Author Response
The manuscript is very well written and organized. The general organization is excellent. It´s quality is near to be published. I have only some questions/recommendations:
Reply: Thanks for your comments.
1) What consisted the high- and low-nutrient soil used in the study? I suggest you to put a table with the soil carachterization. Depending on this variations, you can have varying results! You should discuss it at the end.
Reply: We are sorry that we have not measured the nutrient contents in the soil mixture and only measured those in the nutrient-rich compost. Normally sand contains very little amount of N, P and K so that the amounts of N, P and K in the compost-sand soil mixture roughly equal to those in the compost. Thus, the amounts of N, P and K in the high-nutrient soil is about 9 times higher those in the low-nutrient soil. Mixing nutrient-rich soil (e.g. compost) with sand at different ratios to generate low- vs. high-nutrient soils are commonly used in the literature of clonal plant research (e.g., Birch & Hutchings 1994; Wijesinghe & Hutchings 1997; Wijesinghe & Hutchings 1999; Fransen et al. 2001; and many other studies). We have revised some sentences in this section to make it clear (lines 116-133).
References
Birch, C. P. D., and M. J. Hutchings. 1994. Exploitation of patchily distributed soil resources by the clonal herb Glechoma hederacea. Journal of Ecology 82:653-664.
Wijesinghe, D. K., and M. J. Hutchings. 1997. The effects of spatial scale of environmental heterogeneity on the growth of a clonal plant: an experimental study with Glechoma hederacea. Journal of Ecology 85:17-28.
Wijesinghe, D. K., and M. J. Hutchings. 1999. The effects of environmental heterogeneity on the performance of Glechoma hederacea: the interactions between patch contrast and patch scale. Journal of Ecology 87:860-872.
Fransen, B., H. de Kroon, and F. Berendse. 2001. Soil nutrient heterogeneity alters competition between two perennial grass species. Ecology 82:2534-2546.
2) Please check the text in the parentheses on line 15 (to allow clonal integration from the mother ramet); I think it should be: (to avoid clonal integration from the mother ramet).
Reply: Thanks for pointing out this error. It should be “to prevent clonal integration” or “to avoid clonal integration. We have corrected this error and changed it to “to prevent clonal integration”.
3) On line 150 please check the therm "blue"; it should be "red"
Reply: Thanks for pointing out this error. “blue” should be “green” and we have corrected it.
Reviewer 3 Report
Dear Authors,
Your contribution has a valuable scientific output.
Some transformation of the text, additional data, explanations and corrections should be useful. The details are presented herewith below.
2.3. Experimental design
The text is confusing. It is impossible to understand, what the authors have done.
It is strange, why the authors decided to reduce a ratio of commercial compost for 81 times (1:9 and 9:1) in low-nutrient soil compared to high-nutrient soil? For what purpose did you mix this to different soils, in particular, for the homogeneous treatment? How did you provide the heterogeneity of the soil?
Figure 1. Schematic representation of the experimental design.
The explanatory text does not match the figure.
Lines 132-134
Water was added to the boxes and pots when soil surface became dry. To avoid mass flow of water and thus soil nutrients between adjacent patches within the box, water was added slowly to soil.
Please indicate the soil moisture, and what was the volume of water for soil watering.
Lines 263-269
As expected, clonal integration promoted the growth of the offspring ramets in both the homogeneous and heterogeneous soil environments for all three clonal plant species at no cost to their connected mother ramets (Table 1, Fig. 2). These results are consistent with previous findings of many experimental studies [10,15,18,20,66] as well as two meta-analytical studies[18,19]. The promoted growth of the offspring ramets is likely due to the importation of carbohydrates, nutrients and/or water translocated from their connected mother ramet, as reported before [9,10,16,20,66].
If the homogeneous or heterogeneous soil environment did not make a difference, and this fact is well-known, why did you decide to use these options in your original experiment?
The environmental heterogeneity, no doubt, influences a growth of every plant species. Unfortunately, you failed to incorporate and show this circumstance correctly in your methodology.
Author Response
Your contribution has a valuable scientific output.
Some transformation of the text, additional data, explanations and corrections should be useful. The details are presented herewith below.
Reply: Thanks for your comments. Please see our point-by-point response below.
2.3. Experimental design
The text is confusing. It is impossible to understand, what the authors have done.
It is strange, why the authors decided to reduce a ratio of commercial compost for 81 times (1:9 and 9:1) in low-nutrient soil compared to high-nutrient soil? For what purpose did you mix this to different soils, in particular, for the homogeneous treatment? How did you provide the heterogeneity of the soil?
Reply: Normally sand contains very little amount of N, P and K so that the amounts of N, P and K in the compost-sand mixture roughly equals to those in the commercial compost. For the high and low nutrient soil, we mixed the compost and sand at a volume ratio of 9:1 and 1:9, respectively. Thus, the amounts of N, P and K in the high nutrient soil is about 9 times higher than those in the low nutrient soil. Mixing nutrient-rich soil (e.g., compost) with sand at different volume ratios to generate low- vs. high-nutrient soils are commonly used in the literature of clonal plant research (e.g., Birch & Hutchings 1994; Wijesinghe & Hutchings 1997; Wijesinghe & Hutchings 1999; Fransen et al. 2001; and many others). Then we used the high and the low nutrient soil to create high and low nutrient patches, respectively, and we used an 1:1 (volume ratio) even mixture of the high and low nutrient soil to create the soil used in the homogeneous treatment. In this case, the total amount of nutrients in the homogeneous treatment is exactly the same as that in the heterogeneous soil, so that we can test the effect of soil nutrient heterogeneity (to avoid the effect due to different amounts of nutrients). This type of design for creating homogeneous vs. heterogeneous soil nutrient treatments are widely used in clonal plant literature (e.g., Birch & Hutchings 1994; Wijesinghe & Hutchings 1997; Wijesinghe & Hutchings 1999; Fransen et al. 2001; and many others). We have revised some sentences in this section and also in Fig. 1 to make it clear (lines 116-132 and Fig. 1).
References
Birch, C. P. D., and M. J. Hutchings. 1994. Exploitation of patchily distributed soil resources by the clonal herb Glechoma hederacea. Journal of Ecology 82:653-664.
Wijesinghe, D. K., and M. J. Hutchings. 1997. The effects of spatial scale of environmental heterogeneity on the growth of a clonal plant: an experimental study with Glechoma hederacea. Journal of Ecology 85:17-28.
Wijesinghe, D. K., and M. J. Hutchings. 1999. The effects of environmental heterogeneity on the performance of Glechoma hederacea: the interactions between patch contrast and patch scale. Journal of Ecology 87:860-872.
Fransen, B., H. de Kroon, and F. Berendse. 2001. Soil nutrient heterogeneity alters competition between two perennial grass species. Ecology 82:2534-2546.
Figure 1. Schematic representation of the experimental design.
The explanatory text does not match the figure.
Reply: We have corrected the errors of colors. We replaced “bule dot” with “green dots”, “thick blue lines” with “think green lines”, and “black circle” with “light gray circles”. Now the explanatory text matches the figure.
Lines 132-134
Water was added to the boxes and pots when soil surface became dry. To avoid mass flow of water and thus soil nutrients between adjacent patches within the box, water was added slowly to soil.
Please indicate the soil moisture, and what was the volume of water for soil watering.
Reply: We are sorry that the soil moisture and the amount of water added to the soil were not monitored during the study. The amount of water added varied depending on the weather conditions; this information was added to the text (line x163-164).
Lines 263-269
As expected, clonal integration promoted the growth of the offspring ramets in both the homogeneous and heterogeneous soil environments for all three clonal plant species at no cost to their connected mother ramets (Table 1, Fig. 2). These results are consistent with previous findings of many experimental studies [10,15,18,20,66] as well as two meta-analytical studies[18,19]. The promoted growth of the offspring ramets is likely due to the importation of carbohydrates, nutrients and/or water translocated from their connected mother ramet, as reported before [9,10,16,20,66].
If the homogeneous or heterogeneous soil environment did not make a difference, and this fact is well-known, why did you decide to use these options in your original experiment?
Reply: While the beneficial effect of clonal integration on plant growth is well known, not study has tested the effect of clonal integration on foraging response. The former is not the focus of our study, but the latter is.
The environmental heterogeneity, no doubt, influences a growth of every plant species. Unfortunately, you failed to incorporate and show this circumstance correctly in your methodology.
Reply: Please see our response to the comment on Experimental design. Note that the focus of this study is how clonal integration influence foraging response of clonal plants in heterogeneous environments. Effects of environmental heterogeneity is not the key question of this study. Please also note that not every plant species benefits from environmental heterogeneity, which has been already stated clearly in the original version and also demonstrated in our study (lines 353-356).
