tree size/ sap production

[doop]

Do smaller trees 12"-17" diameter produce significantly less sap and sugar content than 20"-30" trees?

[DrTimPerkins]

Vacuum or gravity?

[JBUTCH2450]

How about on vacuum

[68bird]

I would like to know about gravity!

[doop]

Was thinking about gravity. I have about 50 12"-17 inch, closer to house and hundreds of 20"+ a mile into the woods and would be a pain to get sap out and would like to do a gravity line. Just wondering if It would be worth stringing a line on the smaller ones or if I should just figure a way to transport from the farthest bush..

[Sunday Rock Maple]

Those 50 trees should yield at least 10 gallons of syrup per year on gravity (double that with vacuum). Looks like a good ROI to me.

[spud]

Do smaller trees 12"-17" diameter produce significantly less sap and sugar content than 20"-30" trees?

Smaller trees do not produce significantly less sap then bigger trees (under high vacuum). There are people here on Trader that tap 10 inch trees under high vacuum and get between 25-32 GPT. PMRC has used test trees that were 7 inches (under high vacuum) and has gotten over 30 GPT. The sugar on a smaller tree could be lower though (it is in my woods). I would never not tap a smaller tree 9-12 inches in fear of low sugar. Your always going to have low sugar trees and high sugar trees in your woods. The best you can hope for is an average between 1.6-2.5%. Last year I tapped 5000 and averaged 1.7% under 28 inches of vacuum. I don't think I will ever have an average above 2%. I have over a dozen test trees in my woods that I tap just to test sugar and sap amount. All the test trees are not under vacuum. The smaller trees all tested just 1-1.2% although the big trees (30 inch or bigger) ranged from 1.6-4.0% (in the spring). Last fall the small trees tested just 1% but the big trees were 1.6-1.8%. I started keeping track of GPT last fall and the big trees averaged 8.2 GPT. The smaller trees only averaged 2 GPT (all with no vacuum). I reamed the bigger trees a few weeks ago and want to see how much more sap I will get this spring.

Spud

[Hop Kiln Road]

Last fall the small trees tested just 1% but the big trees were 1.6-1.8%. I started keeping track of GPT last fall and the big trees averaged 8.2 GPT. The smaller trees only averaged 2 GPT (all with no vacuum). I reamed the bigger trees a few weeks ago and want to see how much more sap I will get this spring.


Spud - Interesting. Can you elaborate? You've been running some test buckets since last fall? Also, how would you rate the overall vigor and crown sizes of your trees? Bruce

[spud]

I ran test buckets last spring and fall. Last spring I was only keeping track of sugar content and that is where I averaged 1.6-4.0%. The same big trees were tapped in the fall (November 14th) and averaged 8.2 GPT. Last fall I also tapped 12 smaller trees between 8-10 inches and found they only gave 2 GPT and their sugar was 1%. I concluded ( based on my woods ) that if I was to fall tap I would not waste my time tapping smaller trees. Although my poor man research center is still waiting to see what the smaller trees will produce in the spring for both GPT and sugar content. One year ago I measured a couple of my 8 inch trees and then remeasured them 12 months later. I found my trees grew 1/2 inch in diameter. I would rate my trees as being in very good health and their growth rate to be a bit higher then average. I have read that maples average 1/4 inch per year in a woods setting.

Spud

[DrTimPerkins]

Do smaller trees 12"-17" diameter produce significantly less sap and sugar content than 20"-30" trees?

In general, there is some trend towards increasing sap yields with increasing size (with a single taphole). The trend levels off at about 12" for sap collected on gravity, and somewhat higher, 16"+ for trees on vacuum. Very small trees (<6" produce relatively little sap).

One taphole in a reasonably-sized tree (12") on gravity will produce a given amount of sap. When you add a second taphole in a tree that is bigger (18"), you will produce nearly double (200%) the amount of sap (not quite, but close) cumulatively with the two tapholes. Trees on vacuum are different because we can move sap around more laterally (and vertically upward). In that case, a tree that is 16" will produce about 150% more with two tapholes and about 166% more with two tapholes than with one.

Sap sugar content is somewhat different. It is more related to genetics of the tree and the growth conditions. Trees that are suppressed or in sites with poor nutrition have poor growth, and this reduces sap sugar content. Trees with good genetics and good crown exposure will produce higher sugar content. This is irregardless of size, however you will tend to find lower sap sugar content in smaller trees primarily because they are more frequently suppressed.

One of the best things you can do to increase yields.....THIN! This will release the crop trees, resulting in higher diameter and crown growth, and higher sap sugar contents. Small trees in dense stands produce less sap and less sweet sap. The first thing that should be considered before retubing an area is a thinning.