How to girdle a tree

[terry f]

     I had three fairly large doug fir trees that had huge witches brooms from mistletoe. The first one I fell, the second I left a six foot stump, and the third I want to leave as a wildlife tree. I cut a ring around it and put another one a couple inches above it. The bark was thick, so it was hard to tell how deep I was, but if anything I probably went too deep for what I want. I did this in october, how long before I'll know if it worked? Whats the right way to do this? Should I cut the bark back between the rings, or is chainsaw width enough?

[MHineman]

  I don't have specific knowledge about Douglas Fir, but double girdling is generally enough as long as you get through the cambium layer. 
  When doing TSI, we do a single girdle and squirt 25% glyphosate in the cut  for undesirable species.
  If a desirable species just has a damaged small, or very poorly shaped tree and we want to kill it, we double girdle it.  You can get "flashback" from the glyphosate through the roots to a same species tree nearby and kill or stunt it.

[BaldBob]

Terry,
The chainsaw kerf should be wide enough (especially with a double ring), IF you got all of the cambium layer entirely around the tree. Even a narrow sliver of intact cambium can keep a tree alive for a long time. If it worked you should see the needles turn red by early summer.

[terry f]

     Thanks, I'm sure I went deep enough, and I believe the mistletoe is fed off the cambium layer, so this should kill it too.

[ID4ster]

If you cut a double ring and got a complete cut on the cambium layer on either cut then the tree will be girdled and you'll know in a year or two if it is dead. The xylem layer which is further in the tree than the outer cambium (phloem) layer will allow the root reserves to keep the tree green for a year or two. With the connection from the needles (leaves) cut though the tree will starve since the root reserves can't be replenished.  The mistletoe may accelerate the death of the tree since it is a parasite living off the food of the tree also. I've found though the girdling a tree for wildlife isn't the best thing to do. Typically a girdled tree will fall over in 2-5 years after it breaks right around the girdled area. If you want a stob for wildlife use you would be better off to stand on the top of a CAT and cut the tree off at 15-20 feet in height. This height is enough for the wildlife to use and will provide a longer lasting and more stable wildlife snag than a girdle at 3'. If you really want to make sure the tree is dead though than just take an ax and cut away all the bark and cambium layer between the two chainsaw cuts making sure that all the cambium layer is severed between the two cuts. You only need to completely cut away the cambium layer just underneath the bark. You do not have to go very far into the trunk to sever that connection.

[g_man]

I girdled a 3' white pine the same way you did. I did it one February. For one and a half years after that it looked healthy as an ox. I thought I had failed. But it died during the second winter.

[John Mc]

... Typically a girdled tree will fall over in 2-5 years after it breaks right around the girdled area.

That has not been my experience. I've got a twin-trunked red maple (each trunk about 14") that I girdled 7 years ago (each trunk girdled separately), and a 14" hemlock that was that was girdled 8 years ago. Both are still standing just fine and showing no signs of toppling (and we had several monster wind events in 2011). These are near my home, and I pass them regularly.

Now you've got me curious. I'll have to go visit some other trees I girdled over the past few years and see what's up with them.

The one tree I did have fall after 3 years was a 6" DBH pine - and that one I cut much deeper than I needed to with the chainsaw.

[terry f]

    The two trees I cut down stayed green through most of last summer, then turned fast. I went up this weekend, and the girdled tree was lime green, a little lighter than the ones around it, but still looked healthy. Its been a year and a half, and if anything I thought I cut too deep, but I must have missed something. The mass of mistletoe is about 15 foot wide and 30 foot up, not sure what type of wildlife would use it, but does anyone think its worth keeping, or just firewood it.

[tgalbraith]

You will have to check with Victoria's Secret.  They are the experts in girdling :D :D 8).

[RynSmith]

     The mass of mistletoe is about 15 foot wide and 30 foot up, not sure what type of wildlife would use it, but does anyone think its worth keeping, or just firewood it.

Pretty sure it's used as nesting habitat (at least when it's alive) and I know that squirrels eat the shoots.