Sapwood-heartwood conversion

[dickm]

Son in Law in Michigan was offered some beech from a storm casualty, and sent me the pic of the first trailerload. He wanted to know what caused the sudden colour change in the cross section, and this set me wondering about
the nature of the change from sapwood to heartwood. In these logs, the sapwood seems to occupy more of the cross section than I'd have expected. Any thoughts? (On the logs, not the elderly Saab - they have several of those)

 

[Sgian Dubh]

In some species the transition between living xylem (sapwood) and heartwood xylem is abrupt and clearly visible. Sapwood can remain as living protoplasmic cells for several years but this period varies from species to species, and even within trees of the same species. Has your son-in-law given you any indication of the number of growth rings in the darker ring of wood? Sapwood can remain active for a couple of decades or more, but it can also remain active for only three to five years. As above, sapwood longevity even within a species can vary significantly. I can't tell from your small image, but it wouldn't be a complete surprise to discover the pale core of the stem(s) is a mixture of the pith and some incipient decay, and the dark outer ring(s) is/are mostly heartwood with a near enough indistinguishable thinner band of sapwood. Sapwood in beech (American or European), like other pale heartwood species, can be quite hard to tell apart from the dead heartwood xylem. Slainte.

 

[dickm]

Thanks, SD. Had never really thought about this before, but it's probably not really surprising that the transition should vary between species and within species, depending on the life history. I'll copy your reply to S-i-L; it might take his mind off the broken starter cord on his chainsaw!

 

[Adam W.]

It might be worth showing a decent photo of that dark staining on the bark of the section at front left in the photo.

It looks like it leads to the dark staining throughout the heartwood.

phytophthora ?

 

[Devmeister]

This is crazy and interesting. My experience here is with ponderosa beetle kill. The dap picks up the blue stain and the heartwood doesn’t.

Previous poster mention the xylem. That moves juice up and down. Or is that the cambium.

Any way trees store food in the sap wood. They move it horizontally thru the ring perringee. As the sap dies off it becomes heartwood.

I love where these guys get these names. Very interesting to study the biology of the plants we all like to cut up.

 

[Adam W.]

@Devmeister The cambial layer is where the cell division takes place to produce bark and wood cells. You can also sub-divide these layers into further catagories from the outside inwards - phellem, phelloderm, cortex, phloem, cambium etc.. But it's generally termed phloem (bark) and xylem (wood) for simplicity.

The sapwood generally does the "juice" moving and is full of starch (which is why bugs and fungi like it) and the heartwood provides structural integrity and stores bound water, both contain parenchyma (axial and ray) cells which the tree draws on for nutrients in times of stress, such as drought.

Edit: The parenchyma rays don't always emit from the medulla (pith), but can be intermediate between the medullary rays, but generally they are all called medullary rays for simplicity, again.

Hope that helps.

 

[Old Chippy]

Hi dickm I know from my past woodturning as a hobby some years ago, that Beech particularly if its left lying on the ground for some time starts what was called SPALTING. That is the fungal spores enter into the wood which is the start of the rotting process of timber. This process when stopped by drying at the right time is much valued by artistic woodturners, Beech is noted to be one of the first timbers to start this process. Perhaps that is what's happened to these logs

 

[dickm]

I'll ask one of them to get a decent picture of a balk from the bottom of the tree and another nearer the top, assuming they've not already split everything for the stove. Their house is on the edge of a steep bluff, and daughter lost control of one large balk which skated over the edge and fortunately stopped 60 feet below, just on the edge of the garden of their neighbour their. Could have been VERY expensive.
Think the tree looked perfectly healthy before felling; it was just too near the property.

 

[dickm]

Right, got the story a bit straighter now. This is what she now tells me:-
"At the bottom of the beech tree the wood was actually splitting apart along the colour change, see picture below. The change in colour went along the branches too - you can see in the picture of a split below. And there is also a close up picture of a section from higher up the trunk. Apparently there is some beech disease in the area (I’ve forgotten what it is called I’m afraid) and this tree was taken down either because they thought it had it or it was going to get it."
So there probably is disease involved.

Still, the original question about heart/sap wood is still interesting.

 

[Adam W.]

Thought so, it's a pathogen.

It might be phytophthora, they shouldn't really be transporting it around on the back of an open trailer.

They should burn it all asap, as they've just brought it onto their property.

 

[Sgian Dubh]

It's hard to tell what you have there. I'm not an expert on this, and Adam's suggestion of phytophthora infection is plausible as descriptions I've read discuss mention reddish brown margins to the bleeding cankers formed because of infection. It seems possible to me that the red-brown bleeds could also discolour the tree's heartwood. Here's a link about some briefly described American beech diseases which might be worth a read.

And below is a snap of a cross-section of a yew branch with a bit of labelling identifying different parts. You can see conversion from sapwood xylem to heartwood xylem in this example is quite abrupt occurring somewhere between roughly eight and eleven years after being lain down by the cambium layer. Slainte.

 

[Adam W.]

Well, it doesn't look like Neonectria which leaves distinctive lumpy spots on the bark and is also present in Michigan.