A question about transpiration in deforestation experiments

[Shuai Ma]

Dear all,
I have a problem while studying the effects of deforestation on runoff. I have used some data (such as, precipitation, runoff, evaporation, evaporation from soil, transpiration, etc) of deforest-globe experiments (r1i1p1f1 and r2i1p1f1) and piControl of the CESM2 model. Deforestation experiments caused increases in evaporation and evaporation from soil. However, increased transpiration was observed in deforested areas at lower latitudes, such as the Amazon. I also examined the change in transpiration over time (1850-1929) in these areas and found that transpiration was increasing over time. This may not seem normal. I am eager to know why this result occurs.

The following figure1 shows the average transpiration of the deforest-globe experiment in CESM2 model (r2i1p1f1) minus the average transpiration of the piControl experiment from 1900 to 1929.
The following figure2 shows the average evaporation of the deforest-globe experiment in CESM2 model (r2i1p1f1) minus the average evaporation of the piControl experiment from 1900 to 1929.
The following figure3 shows the average evaporation from soil of the deforest-globe experiment in CESM2 model (r2i1p1f1) minus the average evaporation from soil of the piControl experiment from 1900 to 1929.

I'm looking forward to your reply!

 

[oleson]

Trees were replaced with the nearest neighbor grass, so it could be related to high productivity of the C4 grasses.
See the following paper regarding this issue:

Boysen, L., V. Brovkin, J. Pongratz, D. Lawrence, P. Lawrence, N. Vuichard, P. Peylin, S. Liddicoat, T. Hamima, Y. Zhang, M. Rocher, C. Delire, R. Seferian, V.K. Arora, L. Nieradzik, P. Anthoni, W. Thiery, M. Lague, D. Lawrence, M.-H. Lo, 2020. Global climate response to idealized deforestation in CMIP6 models. Biogeosciences, doi.org/10.5194/bg-17-5615-2020.