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Peer review report 1 on “On the variability of the ecosystem response to elevated atmospheric CO2 across spatial and temporal scales at the Duke Forest FACE experiment”
Agricultural and Forest Meteorology 217 (2016) 352
Contents lists available at ScienceDirect
Agricultural and Forest Meteorology journal homepage: www.elsevier.com/locate/agrformet
Peer Review Report
Peer review report 1 on “On the variability of the ecosystem response to elevated atmospheric CO2 across spatial and temporal scales at the Duke Forest FACE experiment”
1. Original Submission 1.1. Recommendation Minor Revision 2. Comments to Author General This study analyses a large data set of leaf level photosynthesis and transpiration measurements from the Duke FACE experiment, incorporating subdaily data over 10 years. The objective of the study is to explore the spatial and temporal variability of these physiological processes in relation to leaf properties and environment. The leaf properties are described here in terms of the parameters of the models applied. Secondly, the paper studies the implications of three different stomatal models in combination with the Farquhar photosynthesis model. The main conclusions are that a) a lot of variability can be found, and this is mainly due to the environment in short time scales but more due to model parameters in long time scales, and b) while all the different stomatal models fit well to current data, their implications on WUE and other variables indicative of e.g. climate change responses are variable and probably unsatisfactory on the whole. Especially when looking at their Table 2, it seems a concern that all effects studied seem significant for the key parameters of the Leuning and Ball-
DOI of published article: http://dx.doi.org/10.1016/j.agrformet.2016.09.003. http://dx.doi.org/10.1016/j.agrformet.2016.11.136 0168-1923/
Berry stomatal models, suggesting that using those models under variable conditions will be challenging. The topic of the manuscript is highly relevant and the data used is extremely valuable and unique. The manuscript is very well written and clear. I recommend that the study is published, however I have a few minor comments that need to be considered before that. Detailed line 255 Is there a mistake in the formula for calculating lambda? The formula given on line 253 is fine, but the denominator seems to be missing from here, i.e., a similar approximation for dT/dgs as here for dA/dgs. Is this a typo? An explanation is needed. line 333. A union of sets is indicated, but it is unclear what these sets are. I guess the idea is that the union goes over all possible time intervals t (all hours, all days or all years). This should be indicated. Also, it should be more clearly stated that the different time steps are considered separately, i.e., Stot is not over all time steps but separately for hourly, daily and yearly. This becomes clear in the results but should be more explicitly explained here. line 337. The same as above. line 340. The same as 333. Fig. 2: The x axis legends are unclear. It would be better to use negative exponents to make clear what is above and what is below the line. Anonymous Available online 2 December 2016
Contents lists available at ScienceDirect
Agricultural and Forest Meteorology journal homepage: www.elsevier.com/locate/agrformet
Peer Review Report
Peer review report 1 on “On the variability of the ecosystem response to elevated atmospheric CO2 across spatial and temporal scales at the Duke Forest FACE experiment”
1. Original Submission 1.1. Recommendation Minor Revision 2. Comments to Author General This study analyses a large data set of leaf level photosynthesis and transpiration measurements from the Duke FACE experiment, incorporating subdaily data over 10 years. The objective of the study is to explore the spatial and temporal variability of these physiological processes in relation to leaf properties and environment. The leaf properties are described here in terms of the parameters of the models applied. Secondly, the paper studies the implications of three different stomatal models in combination with the Farquhar photosynthesis model. The main conclusions are that a) a lot of variability can be found, and this is mainly due to the environment in short time scales but more due to model parameters in long time scales, and b) while all the different stomatal models fit well to current data, their implications on WUE and other variables indicative of e.g. climate change responses are variable and probably unsatisfactory on the whole. Especially when looking at their Table 2, it seems a concern that all effects studied seem significant for the key parameters of the Leuning and Ball-
DOI of published article: http://dx.doi.org/10.1016/j.agrformet.2016.09.003. http://dx.doi.org/10.1016/j.agrformet.2016.11.136 0168-1923/
Berry stomatal models, suggesting that using those models under variable conditions will be challenging. The topic of the manuscript is highly relevant and the data used is extremely valuable and unique. The manuscript is very well written and clear. I recommend that the study is published, however I have a few minor comments that need to be considered before that. Detailed line 255 Is there a mistake in the formula for calculating lambda? The formula given on line 253 is fine, but the denominator seems to be missing from here, i.e., a similar approximation for dT/dgs as here for dA/dgs. Is this a typo? An explanation is needed. line 333. A union of sets is indicated, but it is unclear what these sets are. I guess the idea is that the union goes over all possible time intervals t (all hours, all days or all years). This should be indicated. Also, it should be more clearly stated that the different time steps are considered separately, i.e., Stot is not over all time steps but separately for hourly, daily and yearly. This becomes clear in the results but should be more explicitly explained here. line 337. The same as above. line 340. The same as 333. Fig. 2: The x axis legends are unclear. It would be better to use negative exponents to make clear what is above and what is below the line. Anonymous Available online 2 December 2016