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9/27/2016 6:53 pm  #1

Pine trees

I noticed that in many pine stands, healthy and not so healthy ones, the new undergrowth are not new pines, but hardwoods. This was especially noticeable along the pine trail ( big crow lake, in an piece of old growth forest), but in many other areas too, like around crotch lake ( healthy red pine stands there)

The only place I saw pine regrowth was along the hemlock bluff trail along hw60.

Does anyone know why this is?


9/28/2016 6:50 am  #2

Re: Pine trees

That's just the natural order of forest succession, I believe. Maples, beeches etc are called "tolerant hardwoods", because they're tolerant of shade -- they grow under the canopy of an established forest. Pines compete best in full sunlight and tend to take over an area when it's devoid of trees. Pines have serrotonous cones that "hatch" when there's a fire so they can be the first to regrow (jack pines are the most extreme example of this but red and white pines do it too to some extent). Red pines in particular are great at colonizing and replenishing depleted soils, which is why red pine plantations are created for this purpose in southern Ontario ex-farmland, with the intent of hardwoods gradually replacing some of the pines as they mature. And white pines never cease to amaze me with the sizes they can attain while perched on a boulder sticking out of a cliff side, in no soil at all but lots of sun.

I haven't done the Hemlock Bluff trail recently enough to remember the understory but if this was right at the cliff, the sunlight exposure from the west may be the reason pine was doing well even in the understory.


9/29/2016 7:41 am  #3

Re: Pine trees

Tentster, you are more likely to see pines colonizing the semi-shaded understory in poplar and paper birch forests... as Dan described, the deep shade of sugar maple forests like those in the Big Crow old growth pine reserve won't allow pine seedlings to survive. IIRC, there are some poplar/birch forests west of Whitney north of Galaeiry and west of Brent in the Cauchon area (the nature reserve there was created to protect a poplar/birch forest over formerly burnt-over lands and these might be colonized with young pines if there are any seed trees in the area). And many more scattered throughout the east side of the park.

Hemlocks are the most shade-tolerant of all the dominant forest trees and they will colonize in the heavy shade of sugar maples, but the process is very slow due to the low light levels and the time needed to transform from a sugar maple forest to hemlock might take hundreds of years. This also requires freedom from disturbance such as fire, wind, insects, or logging, so the chances of any given area escaping disturbance to allow hemlocks to colonize over a time frame of hundreds of years is less. But pines and poplars will move in after disturbance and both being fast-growing species, will grow up quickly to form forest cover.

The recent burn near Achray should show some poplar, birch and pine seedlings colonizing in several years and Bob and Diana McElroy may be documenting this (see their recent post on a TR on the Petawawa).


9/29/2016 12:42 pm  #4

Re: Pine trees

Thanks, thats actually very helpful, and logical now i think about it.  I hadnt thought that actual light requirements would make the difference as to what would grow up first. 

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