Mixed Pine Plantings

[Gary_C]

I was recently looking at some pine plantations that are up for thinning and walked into this one that is every other row being white or norway (red) pine.

 



This is not a good picture because it was late in the day and I had probably walked over 5 miles up and down some difficult terrain. Also the red pine was somewhat thin in these rows although the plan calls for removal of about twice as much red over white pine, but these are operator select and not marked and could just be SWAG. So there could have been an unusually high early mortality in just these particular rows.

I don't have the particulars on this stand, but based on others I saw that day, it probably is a 40-50 year old stand.

Is there some advantage or reason for mixing two different species in alternating rows? Most of the time I see mixed species in a stand, particularly hardwoods and softwoods, they are antagonistic towards the other species. So it seems like this would be a bad idea from the start. Or is that not so true with pines?

[woodtroll]

I am not an expert on red and white pine, But in my opinion most trees are antagonistic to each other regardless of species. They don't know who is next to them. They compete for light and water. They just compete differently for each species. Some grow fast, some handle shade better and so on. The idea of planting a long lived tree in a mono cultured stand if you have a choice seems foolish. How many ash crp plantings have you seen, they are getting wiped out with the ash borer. Beetle problems out west hit single species stands hard.
That being said some thought needs to be given when planing a mixed planting. How will the trees compete? Will the fast growing trees dominate a more desirable slow growing tree? will one species be a good trainer for the other trees.
Who knows why your stand was mixed 40 years ago, it could just be the only trees they had available, so they stuck them in.  The spacing could be natural mortality.

[SwampDonkey]

A few land owners plant them that way simply for diversity. Also on old field with a lot of natural white spruce that may be 4-8 feet tall, they will often be filled with red pine because they take grassy sites well and will catch up to the established white spruce quite well. That was an actual planned strategy to ensure a site is fully stocked. Forestry companies will also plant a secondary species like white pine in with their spruce, maybe 1:1000 ratio for diversity. But also to reestablish the white pine as it's hit hard up here by weevil and rust. Most young white pine we call "cabbage pine" because the bugs and fungus kill the tops (moose to) so you get a whorl that turns up making multi-tops.

[Ron Scott]

We have a lot of mixed pine plantations here also. Many were planted with one row of jack or white pine and one row of red pine. Others are in small blocks of alternate species. They seemed to have done more of the mixed pine plantings years back, especially during the CCC days.

We would now rather have solid blocks of red pine rather than the species mixtures when thinning such areas since we get the best values for the red pine.

[Clark]

Gary - I don't know exactly where this stand is, but if it is in SE MN, then it is on the edge of the range for both red and white pine.  My guess is that they wanted pine, but weren't entirely sure how either would do in the long run.  The white pine could get hit by weevil or eaten by deer before they even grow while the red pine might produce nothing but oxbowed trees since they might not be on a good site.

Obviously neither of those entirely came true, but from your description it sounds like they may have had some issues with red pine early on but overall they seem to be doing fine. 

For estimating the age of red pine, start at DBH (4.5') and count the whorls above that including the leader, add 8 to this and you will be within one or two years of the actual age of the trees.  From what I see I would call this stand ~30 years old, but you had a better view of it then me!

Clark