Why do sugar maples have high % sugar

[BCPP]

Hi all
We run an evaporator during a maple festival that gets around 40,000 visitors so lots of questions about everything maple! One came up yesterday that I'd not thought of so looking to see if anyone knows the answer!

Why do maples, especially sugar maples, have such a high % sugar in their sap? Things don't evolve in nature without a reason so what is the evolutionary advantage that these trees gain by having higher sugar content than say birch or walnut?

[Openwater]

I always assumed that maple trees had high sugar % sap because they generally have more foliage (leaf surface area) than other trees; definitely more than walnuts which have pretty little/scant foliage. Less foliage means less sugar producing capacity. This is just my assumption, but I'm sure there's a more accurate scientific explanation.

[DrTimPerkins]

Why do maples, especially sugar maples, have such a high % sugar in their sap? Things don't evolve in nature without a reason so what is the evolutionary advantage that these trees gain by having higher sugar content than say birch or walnut?

Different trees have different anatomical and physiological strategies for dealing with the functions of life and stresses. We cannot say for sure why sugar maples tend to have a higher sap sugar content (just having substantial sugar in the xylem stream is unusual in itself), but the osmotic forces generated by high sucrose levels are helpful in the xylem embolism refilling process (water uptake from soil) in the spring. Emboli form in the vascular systems of plants due to subfreezing temperatures. Different types of trees cope with these emboli in the vascular system by a host of different mechanisms. Maples (a "diffuse porous species") do this by generating stem pressure that helps to redissolve the bubbles into solution. Birches do it by generating root pressure. Conifers restrict emboli formation by having small trachieds (instead of vessel elements) and other structures to limit emboli spread beyond individual cells or small groups of cells. Oaks and other "ring porous" species grow new vascular tissue very quickly in the spring. So in general...just a variety of ways to skin the "vascular system repair/replacement problem" cat.

[sapman]

In my opinion, they have higher sugar because they were created that way.

[DrTimPerkins]

In my opinion, they have higher sugar because they were created that way.

Yeah, that’s the shortened version of what I said.