Assessing Environmental Control of Sap Flux of Three Tree Species Plantations in Degraded Hilly Lands in South China
, Yann Salmon 4, Xia Chen 1,2, Lei Ouyang 1, Liwei Zhu 1, Guangyan Ni 1, Dan Sun 1, Xinquan Rao 1 and Teemu Hölttä 4Round 1
Reviewer 1 Report
Overall, the authors have revised the manuscript in accordance to the comments of all three reviewers. Thus, I believe the new version of the manuscript is now appropriate for publication in Forests.
I would, though, like to point out a few minor corrections, as follows:
Ln 209: I would recommend using the explanation the authors used for their response to reviewers, thus "Sap flow density and environmental effects".
According to the authors' response, the new figure is showing only day values. However on the figure's legend both daytime and nighttime values are included. The size of fonts used in legends of figure 1, 2, 4 is larger than the ones of figures 3, 5. Please correct.
Author Response
Overall, the authors have revised the manuscript in accordance to the comments of all three reviewers. Thus, I believe the new version of the manuscript is now appropriate for publication in Forests.
Response 1: Thank you for your comments.
I would, though, like to point out a few minor corrections, as follows:
Ln 209: I would recommend using the explanation the authors used for their response to reviewers, thus "Sap flow density and environmental effects".
According to the authors' response, the new figure is showing only day values. However on the figure's legend both daytime and nighttime values are included. The size of fonts used in legends of figure 1, 2, 4 is larger than the ones of figures 3, 5. Please correct.
Response 2: According to your suggestions, we have modified these sentences.
Reviewer 2 Report
The resubmitted manuscript is much improved and I find the submission to be scientifically sound and the results clearly presented. My original comments have been addressed, however I do have a few minor revisions I would recommend before publication.
Figures: I believe Forests requires that the letters in the panel figures should be lowercase. If a letter is included in a panel figure it should be addressed in the caption.
Line 56-57: change to “plantations decreases after approximately 20-22 years after planting”
Line 200: It appears the precipitation data is daily, but the LAI data in monthly, change to “Daily precipitation and monthly Leaf area index”
Table 4 and 5: I am not sure what the “T” lines under each parameter are indicating. This is not mentioned in the table caption and should be made clearer.
Author Response
The resubmitted manuscript is much improved and I find the submission to be scientifically sound and the results clearly presented. My original comments have been addressed, however I do have a few minor revisions I would recommend before publication.
Response 1: Thank you for your comments.
Figures: I believe Forests requires that the letters in the panel figures should be lowercase. If a letter is included in a panel figure it should be addressed in the caption.
Response 2: We have corrected the letters in all figures.
Line 56-57: change to “plantations decreases after approximately 20-22 years after planting”
Response 3: We have modified this sentence based on your suggestion.
Line 200: It appears the precipitation data is daily, but the LAI data in monthly, change to “Daily precipitation and monthly Leaf area index”
Response 4: We have changed this sentence in Line 118 and 205 in revised manuscript.
Table 4 and 5: I am not sure what the “T” lines under each parameter are indicating. This is not mentioned in the table caption and should be made clearer.
Response 5: “T” means “T-value”. We have modified “T” to “T-value” in tables to make it clearer.
Reviewer 3 Report
The reviewer has just read and checked the manuscript entitled as “Assessing environmental control of sap flux of three tree species plantations in degraded hilly lands in South China” written by Qian Wang et al.
The authors continued intensive sapflow measurement for 15 trees of each species (total 45 trees) for about one year. The data is recognized highly valuable to inform and discuss the characteristics of the three species to environmental factors. However, the reviewer considers that there are several significant issues remain as follows in this manuscript and thus it should be majorly revised before reach the standard for publishing the journal “Forests".
The authors applied a multiple regression function with logarithmic transformation (Eq . 4 in the manuscript) estimate the effect of environmental factors on tree transpiration. However, the reviewer could not understand the theoretical reason/background to apply this type of function here: The reviewer found a research report in which normal (not logarithmic) multiple regression function was applied to estimate the effect of potential evaporation (PET) and relative soil water content (RSWC) on tree transpiration (Maréchaux et al., 2018, Functional Ecology, 32), but they probed no cross correlation between PET and SWC at daily scale. Meanwhile some prevailing and useful functions were applied in previous studies to estimate such effect on transpiration estimated with sapflow measurement (e.g. Granier and Bréda, 1996, Annals of Forest Science 53; Pataki and Oren, 2003, Advances in Water Resources 26). Please seek them and select much more suitable function to discuss the effect of environmental factors. Further, instead of (or in addition to) Js, it is strongly recommended to apply each-tree transpiration values and gc (canopy conductance) for the analysis. The reason that the growth of C. lanceolata was severely degraded than other two species should be described in detail. The reviewer suspects that the C. lanceolata stand placed under strongly worse light condition than usual planted forest stands. Unless the objective C. lanceolata represented for those grown around the area, the authors should not consider to compare it with others without additional explanation. Although the authors set the potential problem of plantation as consuming the water especially for dry season, the dry season is cool/cold season and vegetation activity may usually decrease regardless of dry or wet. Thus, original species may have tendency to be dormant under cool—cold condition. Further, the annual rainfall (1600+mm/year) of the observation site is enough to keep SWC +20% even in the cool-dry season, which might not induce severe ET depression for any species at present. Please consider these viewpoints and discuss about them.
The followings are some minor points until the Section 2.
L67: run off --> runoff or flood runoff
L72 : "…no comparative research on…" is recommended to change as: " …no comparative research has been found on…"
L79-L80: "…after more than 30 years. These … influence of a monsoon climate." is recommended to simplify as: …after more than 30 years under a monsoon climate.
L99: Is 1600mm/y actual evapotranspiration? If so, it is very high!
L112: Please describe the details of meteorological instruments (manufacturer, model number, producing country) and measurement heights.
L125: Show also the details of data server if possible.\
L140: ΔT was determined once per week, or determined by 7 days moving window (the day ± 3 days) for each day?
L142: Show the web site from which the program was downloaded.
L147: Js would be equal to transpiration after multiplied by sapwood area.
L156: Daytime average may be more suitable for the analysis instead of using daily average. Please consider.
The reviewer expects that the Result section and Discussion section will be rather revised, therefore only a few things are suggested here about the figures and tables of these sections:
Figure 1 and 2 should be combined, arranged vertically and drawn wider. 3-4 profile lines should be drawn in Figure 3: For example, lines for Jan.-Mar., Apr.-Jun., Jul.-Sep. and Oct. Dec. are recommended. Error bar should be also drawn in the Figure. For reader's easy understanding, numerical tables should be moved to Appendix if they remain, and figures should be increased.
Again, very nice data was obtained by the authors. The reviewer looks forward to the carefully revised manuscript sent soon.
Author Response
The authors continued intensive sapflow measurement for 15 trees of each species (total 45 trees) for about one year. The data is recognized highly valuable to inform and discuss the characteristics of the three species to environmental factors. However, the reviewer considers that there are several significant issues remain as follows in this manuscript and thus it should be majorly revised before reach the standard for publishing the journal “Forests".
Response 1: Thank you for your comments and giving us an opportunity to revise this paper.
The authors applied a multiple regression function with logarithmic transformation (Eq . 4 in the manuscript) estimate the effect of environmental factors on tree transpiration. However, the reviewer could not understand the theoretical reason/background to apply this type of function here: The reviewer found a research report in which normal (not logarithmic) multiple regression function was applied to estimate the effect of potential evaporation (PET) and relative soil water content (RSWC) on tree transpiration (Maréchaux et al., 2018, Functional Ecology, 32), but they probed no cross correlation between PET and SWC at daily scale. Meanwhile some prevailing and useful functions were applied in previous studies to estimate such effect on transpiration estimated with sapflow measurement (e.g. Granier and Bréda, 1996, Annals of Forest Science 53; Pataki and Oren, 2003, Advances in Water Resources 26). Please seek them and select much more suitable function to discuss the effect of environmental factors. Further, instead of (or in addition to) Js, it is strongly recommended to apply each-tree transpiration values and gc (canopy conductance) for the analysis. The reason that the growth of C. lanceolata was severely degraded than other two species should be described in detail. The reviewer suspects that the C. lanceolata stand placed under strongly worse light condition than usual planted forest stands. Unless the objective C. lanceolata represented for those grown around the area, the authors should not consider to compare it with others without additional explanation. Although the authors set the potential problem of plantation as consuming the water especially for dry season, the dry season is cool/cold season and vegetation activity may usually decrease regardless of dry or wet. Thus, original species may have tendency to be dormant under cool—cold condition. Further, the annual rainfall (1600+mm/year) of the observation site is enough to keep SWC +20% even in the cool-dry season, which might not induce severe ET depression for any species at present. Please consider these viewpoints and discuss about them.
Response 2: Thank you for your comments and giving us an opportunity to revise this paper. There are many types of functions that have been used in the literature to describe the relationship between environmental factors and tree transpiration rate. Therefore, the choice of which function or format to use is a difficult one and was based mainly on the goodness of the fit. We have tried many functions and found that type relation in equation 4 gave best fits. Note that it corresponds to a power function relationship between the environmental drivers and tree water use, as is written on lines 165. This type of function also resembles quite closely the functions used in the widely used optimal stomatal control model (e.g. Hari et al. 1986, Hari & Mäkelä 2003) and Medlyn model (Medlyn et al. 2011) to describe stomatal behavior in response to light and VPD (they describe transpiration rate being approximately proportional to VPD0.5, and transpiration rate being a saturating function of PAR or linearly related to photosynthesis rate). Based on other reviewers’ suggestion, we deleted all the content of transpiration and only focus on sap flow. Therefore, using the sap flow values in the analysis is to maintain consistency throughout the paper. From Table 4 and equation 4, we can know the relation between canopy conductance per sapwood area (g) and environmental factors in line 236-238 in revised manuscript.
Sorry, we did not think that the C. lanceolata stand placed under strongly worse light condition than usual planted forest stands, because the LAI in C. lanceolata site was lowest of three sites. We have added one paragraph to discuss why the Js of C. lanceolata was severely lower than other two species (in line 355-377 in revised manuscript).
We agree that now the annual rainfall (1600+mm/year) of the observation site is enough to keep SWC +20% even in the cool-dry season, which might not induce severe ET depression for any species. However, long-term observations have shown that rising air temperature in southern China has shifted the rainfall patterns toward intensified rainfall (i.e., more floods) but has not raised the soil water content (SWC) in the wet season, while droughts are becoming frequent and more severe leading to declining SWC in the extended dry season. Rising air temperature will also increase the VPD with the potential problem to create atmospheric drought, which may lead to stomatal closure. Hu et al. (2018) also showed that the dry season extended from November–March during the 1964–1983 period to October–April during the 2001–2010 period in the Heshan area (our sites), and they found that the extended dry season reduced transpiration in Schima superba (same family as S. wallichii). For two original species, the positive correlation between Js and SWC indicates that water availability was limiting their water use in the dry season. So we speculate that the more drought sensitive native species S. wallichii and C. lanceolata could suffer more severely from water stress under future meteorological and soil conditions. Considering your insightful viewpoints, we have added another paragraph to discuss how the three species respond to changing climate in the future (in line 378-388 in revised manuscript).
Hari, P., Mäkelä A., Korpilahti, E., Holmberg, M. (1986). Optimal control of gas exchange. Tree Physiology, 2, 169-175.
Mäkelä A., Hari, P. (2003). Annual pattern of photosynthesis in Scots pine in the boreal zone. Tree Physiology, 23, 145-155.
Medlyn, B. E., Duursma, R. A., Eamus, D., Ellsworth, D. S., Prentice, I. C., Barton, C. V., ... & Wingate, L. (2011). Reconciling the optimal and empirical approaches to modelling stomatal conductance. Global Change Biology, 17(6), 2134-2144.
Hu, Y.T.; Zhao, P.; Shen, W.J.; Zhu, L.W.; Ni, G.Y.; Zhao, X.H.; Zhang, Z.Z.; Rao, X.Q.; Ouyang, L.; Zeng, X.M.; Sun, D.; Lin, Y.B. Responses of Tree Transpiration and Growth to Seasonal Rainfall Redistribution in a Subtropical Evergreen Broad-Leaved Forest. Ecosystems. 2018, 21: 811-826.
The followings are some minor points until the Section 2.
L67: run off --> runoff or flood runoff
Response 3: According to your suggestion, we have modified this sentence.
L72 : "…no comparative research on…" is recommended to change as: " …no comparative research has been found on…"
Response 4: Sorry, we think that “no comparative research on …has been published” might be better.
L79-L80: "…after more than 30 years. These … influence of a monsoon climate." is recommended to simplify as: …after more than 30 years under a monsoon climate.
Response 5: We have changed this sentence based on your suggestion.
L99: Is 1600mm/y actual evapotranspiration? If so, it is very high!
Response 6: Sorry, we checked this sentence and deleted it.
L112: Please describe the details of meteorological instruments (manufacturer, model number, producing country) and measurement heights.
Response 7: We have added these details in line 115-116 in revised manuscript.
L125: Show also the details of data server if possible.\
Response 8: Sorry, the station staff provided this soil water content. We did not have the details of data server.
L140: ΔT was determined once per week, or determined by 7 days moving window (the day ± 3 days) for each day?
Response 9: ΔT was determined by 7 days moving window (the day ± 3 days) for each day.
L142: Show the web site from which the program was downloaded.
Response 10: We have added newest program’s web site in line 146 in revised manuscript.
L147: Js would be equal to transpiration after multiplied by sapwood area.
Response 11: We agree with the reviewer that Js would be equal to transpiration after multiplied by sapwood area. Here we just presume that Js is equal to canopy transpiration to estimate canopy conductance per sapwood area.
L156: Daytime average may be more suitable for the analysis instead of using daily average. Please consider.
Response 12: Many studies (e.g. Daley and Phillips, 2006; Marks and Lechowicz, 2007) have reported that there was nighttime sap flow. So we think it might be better to use daily average data.
Daley MJ, Phillips NG. 2006. Interspecific variation in nighttime transpiration and stomatal conductance in a mixed New England deciduous forest. Tree Physiology 26:411–419.
Marks CO, Lechowicz MJ. 2007. The ecological and functional correlates of nocturnal transpiration. Tree Physiology 27:577–584.
The reviewer expects that the Result section and Discussion section will be rather revised, therefore only a few things are suggested here about the figures and tables of these sections:
Figure 1 and 2 should be combined, arranged vertically and drawn wider. 3-4 profile lines should be drawn in Figure 3: For example, lines for Jan.-Mar., Apr.-Jun., Jul.-Sep. and Oct. Dec. are recommended. Error bar should be also drawn in the Figure. For reader's easy understanding, numerical tables should be moved to Appendix if they remain, and figures should be increased.
Response 13: Thank you for your very helpful suggestions. We have combined Figure 1 and 2 based on your suggestion. For Figure 3, in each site, SWC was measured every 30 mins, at 5, 10, 20, 30, 40, 50, 60, 90, 120, and 150 cm depths at three locations during 2017. We averaged each layer of three locations in each day to get one single point within season for each site. It was an integrative data over a long period. So we cannot draw 3-4 profile lines in Figure 3 but error bar have already been drawn in Figure 3. We have put the relevant numerical tables in the Appendix and only keep the necessary numerical tables in the manuscript.
Again, very nice data was obtained by the authors. The reviewer looks forward to the carefully revised manuscript sent soon.
Response 14: Thank you for your comments and we will revise the manuscript as soon as possible.
This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.
Round 1
Reviewer 1 Report
The ms ‘Environmental control of water use of three tree species plantations in degraded hilly lands in South China’ deals with an important topic related to the forest ecology and management and afforestation. The aim of the AUs was to select the more suitable species for planting in degraded hilly lands on the basis of their water use and adaptive water-use strategy, in a view of changing climate. The water use was compared in three species as two broadleaves A. mangium, S. wallichii, and a conifer C. lanceolata. Water use was estimated by canopy stomatal conductance upscaled by xylem sap flux density (Js) and the relative control of some environmental parameters and soil water content investigated. On the basis of their results, AUs concluded that the exotic species A. mangium, which prefers higher temperatures and drier soil, will become more suitable in southern China, whereas the more drought sensitive native species S. wallichii and C. lanceolata could suffer more severely from water stress under future meteorological and soil conditions.
Although the ms is well written and sound I have some concerns about the structure, the M&M section and the metodology applied to the canopy stomatal conductance determination.
About the ms structure, I found very confusing to present Fig 1, 2 and table 3 within the M&M section. I suggest to move them to the results section and to discuss the results accordingly.
Another obscure point is related about the critierion used by the authors to select “small and large trees” (line 199). Could you better explain? Is there a diameter threshold?
Line 224-225 – “mean SWC of all layers between the wet and dry seasons was greater at the A. mangium and S. wallichii sites than at the C. lanceolata” site (Figure 5)”. How is the se calculated (Were there experimental replicate for SWC?)? Regarding to the Figure 5: How did AUs calculate these data? Is it a single point within season or it is an integrative data over a long period?
These are only a few weak points of the M&M and I suggest AUs a deep re-organization with a more detailed description of the field experimental site.
I have some concerns about the use of equation 7 for the canopy stomatal conductance determination. As stated by AUs, the assumption is that Js is equal to canopy transpiration if Js is not influenced by hydraulic capacitance. Based on this point my feeling is that eq 7 could be used if the hydraulic capacitance of the trees are similar or if trees of the same species are compared. As water stored within plant tissues can sustain more than 1 or 2 days of maximum transpiration (Breda et al., 2006) and that the stem/root/shoot hydraulic capacitance can support canopy transpiration under water deficit condition, AUs could not exclude that the differences found between species could be related to different hydraulic capacitance of the woody compartments within each specie. As reported by Barnard et al., 2003 I suggets to AUs to calculate Huber value (sapwood to tota leaf area ratio) and to verify if the equation 7 could be used in their condition at least. In other words AUs should prove that compensatory mechanisms (related reduction total leaf area over the sapwood area) reduced the effects of different sizes of the species on Js.
Js was higher in A.mangium than S. wallichii but on June the lastes have a double LAI than former. How could be the effects of the LAI increase in S. wallichii on canopy stomatal conductance?
The discussion should be improved on these points:
Line 334-335. The period should be newly write in more comprehensive way.
Line 341-344. Table 3 did not report SWC...please check;
Line 344: …stomatal behaviour…the Aus did not measure stomatal behaviour but only sap flow density;
Line 346-347: this point is speculative. AUs cannot prove this statement. Please insert some evidences to support this point;
Line 352-353: the period should be newly written making more clear.
Line 354-356….The apparent canopy stomatal conductance response of these species was much
stronger in daily than in hourly scale during the dry season….this is another point supporting my concerns related to the equation 7;
Line 384-385: If this point was verified, the previous statment about the negative effects of exceeding water in the soil was not true anymore. Thus A. mangium trees could uptake water from the deeper soil layers where SWC was < of field capacity (Figure 5). This behaviour could partailly explain the higher SWC in the first layers of A. mangium (water uptake were reduced) than C. lanceolata;
Line 416: please specify the term AM and CL;
Line 416:… good access to radiation…please specify
Finally I suggest to modify the title as “Assessing environmental control over water use...”
Author Response
Please see the attachment
Author Response File: 
Author Response.docx
Reviewer 2 Report
The submitted manuscript investigates the environmental controls of water use in forest plantations of South China. Three tree species were included in the study two of which were native and one non-native species. The study was well designed and I commend the authors on for properly applying the TDP technique by including information on Tm calculation and accounting for radial variability in Js. The data analysis was well executed and the interpretation of results was well done. I found the manuscript to be very interesting and have no major concerns regarding the submission. I do, however, have several minor comments on how the manuscript should be improved and have provided these below. My changes are provided in bold for a given line.
Line 25: Define “Js” after “control”. This is the first appearance.
Line 27: “Using the thermal”
Line 32-33: “Demonstrate that the three”
Line 43: “Environmental”
Line 54-55: “Plantations decreases after about 20-22 after planting”. Also, I am not quite sure what you mean by “weakened the photosynthesis and water use.” Maybe a sentence like: “Observations show that the growth, photosynthetic rate and water use of A. mangium plantations decreases after about 20-22 years after planting [12].” Would work better.
Line 56: “Therefore, understanding the water use”
Line 58: “tree species used for timber production and”
Line 71: “comparative research”
Line 87: “studied”
Line 103: “The plantations were located close to each other”
Line 105-108: The discussion on LAI sounds more like a result. How was this measured? LAI methods should be included and results along with Figure 1 should be moved to the results section.
Line 94: Add some more information on the plantations in this section. Most importantly, how old were the trees? If you have information on silviculture activities such as fertilizer applications of vegetation management treatments, consider adding that as well.
Line 118: “and data was provided”
Line 119: “sites was 300, ”
Line 120: “Hourly averages were used for all meteorological data and we calculated VPD (kPa) according to Campbell and Norman, 1998 [27]:”
Line 138: “as follows Granier, 1987 [25]:”
141: “was determined on nights when VPD”
Line 164: “can be obtained from these”
Line 218: “accounted for 77%”
Line 231: “Monthly precipitation” [delete “change in”].
Line 234: “(C) relative humidity” This should be c you have b twice. Also change so that figure and panel letters are all lowercase.
Line 250: “The only significant difference found was”
Line 328: add a “.” To the end to of the caption
Line 335 and 336: The incorrect table is being referenced in this section.
Line 337: It may be worth to specifically point out that a low β2 indicates tight stomatal control as if this wasn’t the case increases in VPD would increase Js. This will help some readers to better understand your results. I can’t recall if this was done earlier in the manuscript.
Line 340: “Water use strategy”
Line 344: Again, this is the wrong table reference
Line 345: Again, this is the wrong table reference
Line 346: Again, this is the wrong table reference
Line 348: Again, this is the wrong table reference
Line 354: Again, this is the wrong table reference
Line 358: Again, this is the wrong table reference. Check all table refences in the discussion. I will no longer mention this.
Line 371: Incorrect figure number referenced. Check all Figure and Table references.
Reviewer 3 Report
The authors dealt with the interesting topic of water balance in plantations in a subtropical monsoon region of south China. The topic is important in the light of climate change and the scientific approach is appropriate, but improvements in results' presentation are needed before the manuscript can be suitable for presentation.
My major remarks have to do with the results' section of the work, as indicated below:
In the abstract (Ln 29), in the keywords and in Materials and Methods (Ln 177-179), the canopy stomatal conductance (g) is mentioned. However, no such results are presented in Tables or Figures. There is no consistency in the way the data are presented. The seasonal variation of Js is not shown (as it is done for example for Q in Fig. 7). Data of Js are presented through the correlation of Js with each single environmental parameter (Fig. 6), although the statistical model describing the environmental control on Js tests the combined effect of at least 3 parameters. Thus, the rationale of Fig. 6 is not clear. I would suggest either (a) keeping Fig. 6 but adding R2 and p level in each subplot, so that one can see if the effect of each single environmental parameter is stronger or not that the effect of their combination or (b) replacing Fig. 6 with the seasonal data of Js (as for Q). Moreover, there is no point in including Js max of each tree in Table 3. Js belongs to the results and not in the materials and methods. It is, furthermore, not necessary to show the DBH and height of each single measured tree. It would be better to show mean tree DBH and height ± SE and include this data in Table 1. Water use (Q) is one of the tested parameters. However, no statistical analysis is done on the effect of environmental parameters on Q. Is it because Q and Js are not independent parameters? Still, it is unbalanced to present such a detailed analysis of Js and only a short description of Q. This cannot support the discussion on "whole tree water use" (Pg.12). Moreover, in this part why is Q discussed in relation to DBH range? Figs 7a,b,c do not show DBH, thus it is hard to follow what is written in Ln 312-320. This concept and the data presented in Fig.8 is interesting, but is not relevant to the objectives and the title of the manuscript, which is the environmental control on water use. The same applies for the discussion in Ln 398-418. In the Discussion there is a confusion between Tables (e.g. Table 3 should be replaced by Table 4 in Ln 336, 344, 345, 354 and Table 4 by Table 5 in Ln 354). Check the text carefully, since this makes reading difficult. The term "Water stress" includes both the stress resulted by flooding and by drought. Since both effects are found in this study, the authors should pay attention and precisely mention flooding stress or drought stress in the respective parts of the discussion.Minor comments:
Title: Since “water use” is used for Q (which is a small part of the work), it is confusing to use this term in the title. Please rephrase. Add in the abstract a short sentence explaining why the 3 species were comparatively studied, as you mention in the introduction. Ln 25: The explanation of Js should be given the first time the abbreviation is used. Ln 55-56: What is the purpose of this phrase? This is true for all trees, especially the fast growing ones. Be more specific. Ln 88-92: You don’t mention the assessment of Q in your objectives. As mentioned previously there is an inconsistency throughout the paper. Either keep only Js and refer to the study of sap flux, or present in more detail Q as well, and talk about studying the water use strategy or water balance in total. Ln 100-101: It would be helpful for the reader to add a bar on the X-axis of Fig. 1, 3, 4 indicating the wet and the dry season. Ln 104: Elevation, declination and slope are not given in Table 2. Ln 105-106: How was LAI measured? Table 1. What is the age of the plantations? Is the higher tree density and lower total stand basal area due to younger age of C. lanceolata? Ln 220-221: Although a difference in VPD is mentioned, this is not clear by fig. 4b. On the contrary VPD shows very high fluctuation and a more or less constant trend. Figs 3 and 4: Include precipitation as an additional subplot in Fig. 4 (daily values). Fig 3 is not informative as it is. Ln 239: What is meant by “regulations”? Ln 243-244: This is not precise. Ln 244-246: From Fig 4b it is not clear that VPD is higher during the wet season. It is mostly PAR and Tair that are really higher during this period. Ln 250-251: Delete this sentence. Ln 264: At which depth is SWC measured in plots C, F, L? 6: Since only daytime values are presented in fig. 4, night time values should be excluded also from fig. 6. Ln 289-291: Delete or transfer to discussion. Ln 425-428: Transfer this sentence to discussion.
