Regulation of Vegetation and Evapotranspiration by Water Level Fluctuation in Shallow Lakes
, Liqiao Liang 3,*, Xiaomin Yuan 1,2, Sirui Yan 1,2, Miao Li 1,2, Shuzhen Li 1,2, Xuan Wang 1,2 and Chunhui Li 1,2Round 1
Reviewer 1 Report
The Present study deals with the effect of water level fluctuations in shallow lakes and their effect on vegetation and evapotranspiration. The study seems interesting however I have two main points which need further discussion.
- In conclusion (i) The abrupt rise in annual water level causes disturbances to aquatic vegetation communities. how and why?
- In conclusion(ii) why low water levels showed high ET values? The authors need to discuss this point in detail.
- Some minor comments: In the mat and method section; the study site, the longitude, and latitude of the mentioned lake should be mentioned there itself.
- In data and field experiments; references are needed especially from line no. 113-116.
Author Response
Comments and Suggestions for Authors
The Present study deals with the effect of water level fluctuations in shallow lakes and their effect on vegetation and evapotranspiration. The study seems interesting however I have two main points which need further discussion.
- In conclusion (i) The abrupt rise in annual water level causes disturbances to aquatic vegetation communities. how and why?
Response：Baiyangdian Lake belongs to a shallow-water lake system type, for which water-levels range from 6.5 m to 9.5 m. Due to its unique wetland topography and vegetation composition (mainly P. australis community), small water-level fluctuations typically cause significant alterations in vegetation cover and open-water area. To alleviate water shortages, ecological water transfer projects have been implemented in the lake since the 1980s to maintain its integrity, as showed in Fig. 2c. The abrupt rise in water level especially in the initial growing stage can alter the vegetation distribution.
- In conclusion(ii) why low water levels showed high ET values? The authors need to discuss this point in detail.
Response：As the Baiyangdian Lake belongs to a shallow-water lake (water level at 6.5 m is regarded as dying up water level), decreasing in water level means extending for the suitable water level of P. australis community. In fact, evapotranspiration for P. australis community is larger than evapotranspiration of open water. In this way, the expanding in P. australis area and shrinkage in open water area with decreasing of water inevitable cased the higher ET values.
3.Some minor comments: In the mat and method section; the study site, the longitude, and latitude of the mentioned lake should be mentioned there itself.
Response: The longitude and latitude of the Baiyangdian Lake has been added in the revised manuscript.
- In data and field experiments; references are needed especially from line no. 113-116.
Response：The references have been added in this section.
Reviewer 2 Report
The article describes processes of influence of water level fluctuations in shallow lakes on vegetation and evapotranspiration. The results indicate that water level fluctuation controlled biological and ecological processes and their structural and functional characteristics. The overall scientific level of the paper is very high. The authors specified three objectives which were very well explored using adequate techniques. There are some questions to be answered (see specific comments), after this is done satisfactorily the paper can be published in Water.
Specific comments:
Line 104 … which was obtained …
Line 139 … [21, 24] under the assumption of independence.
Question to the authors: was the independence tested?
Line 160 in the equation (4) I cannot find the definition for Sw , Sp,a,
Line 192 I cannot find the definition As in eq. (6)
Line 193 Ac ?
Line 208 Fig 2b: C1 and C2 is not defined, These are supposed to be abrupt changes for water level. Those changes should be better described. Also the 0.96 confidence bands are not discussed. Following the definition, 0.96 confidence bands imply that 96% of observations lie within those bands. It does not seem to happen. The authors should give some explanation what is happening.
Line 228 The same comments as for Fig. 2
Line 239-241: it would be interesting to know when such changed occurred.
Line 355 … This study explored water level fluctuations during ???? there is something missing
Author Response
The article describes processes of influence of water level fluctuations in shallow lakes on vegetation and evapotranspiration. The results indicate that water level fluctuation controlled biological and ecological processes and their structural and functional characteristics. The overall scientific level of the paper is very high. The authors specified three objectives which were very well explored using adequate techniques. There are some questions to be answered (see specific comments), after this is done satisfactorily the paper can be published in Water.
Specific comments:
Line 104 … which was obtained …
Response：Improved！
Line 139 … [21, 24] under the assumption of independence.
Response：Improved！
Question to the authors: was the independence tested?
Response：The Mann-Kendall test has been widely used to abrupt changes in the hydrometeorological variables. And hydrometeorological variables have been assumed as independence.
Line 160 in the equation (4) I cannot find the definition for Sw , Sp,a,
Response：The wetland vegetation parameters of each cell adopts a specific state, such as Sp.a, Sw and S0, representing the P. australis community, open-water area and arable or bare land area, which was presented in the revised manuscript.
Line 192 I cannot find the definition As in eq. (6)
Response：Total available energy for the surface is first partitioned by a layer approach into two portions: the canopy part (Ac) and the soil part (As). This has been added in the revised version.
Line 193 Ac ?
Response：Total available energy for the surface is first partitioned by a layer approach into two portions: the canopy part (Ac) and the soil part (As). This has been added in the revised version.
Line 208 Fig 2b: C1 and C2 is not defined, These are supposed to be abrupt changes for water level. Those changes should be better described. Also the 0.96 confidence bands are not discussed. Following the definition, 0.96 confidence bands imply that 96% of observations lie within those bands. It does not seem to happen. The authors should give some explanation what is happening.
Response：This has been explained in the caption of Fig. 2 as “The u representes statistics variables in the Mann-Kendall method, C1 and C2 is statistica variables calculated from normal and invert series. The intersection point of C1 and C2 located between the confidence lines (±1.96 at 95% confidence line) is the time of the abrup changes (Mann, 1945; Kdendall, 1948)”.
”
Line 228 The same comments as for Fig. 2
Response：This has been explained in the caption of Fig. 2 as “The u representes statistics variables in the Mann-Kendall method, C1 and C2 is statistica variables calculated from normal and invert series. The intersection point of C1 and C2 located between the confidence lines (±1.96 at 95% confidence line) is the time of the abrup changes (Mann, 1945; Kdendall, 1948)”.
Line 239-241: it would be interesting to know when such changed occurred.
Response: The decreases in P. australis mainly resulted from decreasing in suitable water level for P. australis, which has been added in the improved version as “In this study, an abrupt change occurred at an approximate water-level of 6.59 m, wherein P. australis area slopes were -46.24 and -1.91 km2 m-1 for water-levels ranging from 5.43–6.59 and 6.59–9.50 m with decreasing of suitable water level for P. australis, respectively”.
Line 355 … This study explored water level fluctuations during ???? there is something missing
Response：This sentence has been improved as “This study explored water-level fluctuations, analyzed their influences on fractional vegetation cover (Fv), and simulated vegetation patterns and evapotranspiration (ET) under different water-levels over time.
