Large crack in felled Cedar stump

[bjam1964]

We have just spent a couple of cold days felling a 100 odd year old cedar. There had been considerable storm damage to the canopy, especially in the upper crown and most of the branches overhanging the neighbours property had been removed. Sadly, an impending building project, permission granted, required the premature removal of the tree.

 

After "stunt" felling the tree I was surprised to see a prominent crack across the stump. There were no external signs of this split, the cause unknown. After digging out the stump (6 hours with a 3 ton excavator) I managed to split the tree in half using nothing but hi-lift felling wedges and a bit of sledge hammer effort. The wedges were placed in the crack which extended all of the way through the root plate and into the soil.

 

Has anyone seen anything similar? A VTA based risk assessment was conducted before climbing but I could not see any external signs to indicate the presence of the crack. Your thoughts and comments appreciated.

 

The whole tree before felling

 

The stump with 660 36" bar for scale.

 

The crack!

 

The stump in two halfs - looking at the vertical face of the crack

Edited December 2, 2010 by bjam1964

[bjam1964]

I guess what I am asking here, from the more experienced members, is what they think may have caused this vertical crack in a tree of this size and what the likely hood of the trunk splitting in two under a severe rotational loading? Has anyone else felled a 36" Cedar and found such a significant weakness/fault with no external signs?

[Lee Winger]

Cedars don't grow very well here imo, I've seen cracks like this before quite often it looks like included bark, what causes this imo a combination of poor growing conditions, and as you say rotational loading, I guess the split carried on up the trunk? isn't this called shake, the tree in your picture looks a bit top heavy imo too

[Stephen Blair]

i would call that a shake and i reckon it wasnt there until you felled the tree, i find it happens when you take a lot of weight off quickly, i have knocked big crowns out of trees and the flush cut has been fine, give it a few minutes and along comes a big shake.

[Lee Winger]

i would call that a shake and i reckon it wasnt there until you felled the tree, i find it happens when you take a lot of weight off quickly, i have knocked big crowns out of trees and the flush cut has been fine, give it a few minutes and along comes a big shake.

 

Good point never thought of that

[Big 'Ammer]

I would say the shake is already there at the bottom, when you have knocked the top out the pressures change in the timber and it splits up further after a few minutes.

 

Happens with Turkey oaks a lot, too.

[Mark Bolam]

That's how I see it too. The shake widens as the compression is released.

 

That defect was clearly there before you felled it.

 

Could have been a really funky 50% reduction....

[skyhuck]

You say it was split in half with just wedges, but in the picture its clear that the left side has been cut with a saw.

[Treegeek]

Heart shakes dark discolouring shows it was there before felling the crown looks fairly unbalanced could be cavitation fracture IMO

[bjam1964]

You say it was split in half with just wedges, but in the picture its clear that the left side has been cut with a saw.

 

You are right - I started with the saw and, once the wedges were placed it fell apart along the crack and not where it had been cut!

 

I released this tree off the stump with a dogs tooth - good job as the crack was a felling incident waiting to happen - shocking.