What are the bubbles that come out of the tree with the sap?

[PerryW]

Are the bubbles just air, or are they CO2? Always wondered. Seems like they comprise about 50% of the volume that goes thru my laterals.

[DrTimPerkins]

Are the bubbles just air, or are they CO2? Always wondered. Seems like they comprise about 50% of the volume that goes thru my laterals.

If they are leaks, then the bubbles are air (a mixture of gases, nitrogen, oxygen, carbon dioxide).

If they are truly coming out of the tree (which does happen, especially as it gets warmer), then it is air that is somewhat enriched in carbon dioxide and depleted in oxygen. Trees have to "breathe" too. When they metabolize (conduct physiological activity), in some of those processes oxygen is typically consumed and carbon dioxide is generated....except during photosynthesis (not a factor this time of year with no green leaves).

[PerryW]

thanks. I guess I always figured the all the photosynthesis happened in the leaves and that any gas exchange (CO2 -> O2) would happen there.