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Pioneer species vs. Intolerant species ?

Started by BrandonTN, August 27, 2008, 10:15:57 PM

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BrandonTN

I'm reading my silviculture text, and am kinda confused.  Can a tree be considered "intolerant" without being a "pioneer"?

I understand what a pioneer species does(grows first after a disturbance), and understand what an intolerant species is(one that can't stand shade), but my book was saying that "Some intolerant species have to live long b/c they rely on infrequent disturbances to reproduce."  ...But then next paragraph it says: "Many pioneer species have even less capacity for individual longevity[than tolerant species]."  --it makes it sound like they're not necessarily the same thing to me.
Forester, Nantahala National Forest

WDH

Quote from: BrandonTN on August 27, 2008, 10:15:57 PM
I'm reading my silviculture text, and am kinda confused.  Can a tree be considered "intolerant" without being a "pioneer"?

Oh yes.  Take Black Walnut for example.  It is shade intolerant, but the large seed is not easily disseminated, so it is a poor pioneer species.  But it is decidely shade intolerant.  Another example is Cherrybark Oak.  Decidely intolerant as well, but the acorn does not float well in the wind, so a pioneer it is not. 

Shade intolerance and pioneer colonization is often synonomous, but there are notable exceptions.  A tree with a big heavy seed can be intolerant, but not be designed as a good pioneer.
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Brian Beauchamp

Pioneer species is a vague term because it depends on what species are present to determine what tree species shall be deemed as 'pioneer species' in any given location. Site has a huge influence on what competes well early on. In the Baraga Plains of MI, the sand dunes are going to likely be covered with Jack Pine after disturbance, yet on bottomland soils, they aren't as likely to be around because they just aren't able to compete as well as other species.

What the take home message is when thinking about pioneer species is...think about what is going to take the place of the trees that are present once they are removed or what is going to populate an area after a disturbance regime is reduced or eliminated and realize that, as a forester, you will make logical decisions based upon that information to manipulate stand composition. Knowing the trees of seed bearing size/age, seed dispersal distances and regeneration data will be vital information in making these decisions along with knowing what disturbance and timing of that disturbance creates conditions that are optimal for the species you want to be present, or in some cases, what you do not want to be present.

To me like I said, it is a vague term...and outdated. Early seral stage or early successional species are now more appropriate terms in my opinion.

SwampDonkey

Yellow birch is another tree that's kinda hard to fit the "criteria". It's not a pioneer, it's long lived, and has tons of seed in good years. Harvest a dominant sugar maple stand with a few scattered yellow birch as it grows up here and you might possibly have a new stand of hardwood dominated by another species. Instead of sugar maple, it's yellow birch which is intermediate in shade tolerance.  8)

Some sites I can't figure out. Sometimes the maple is over topped by the yellow birch and stagnates and on other sites the sugar maple grows faster than the yellow birch, all from seed not suckers. One site we are on now has yellow birch 7-8 meters tall and the maples are about 3 meters tall and skinnier than raspberry canes and thicker than dog hair.  ::)
"No amount of belief makes something a fact." James Randi

1 Thessalonians 5:21

2020 Polaris Ranger 570 to forward firewood, Husqvarna 555 XT Pro, Stihl FS560 clearing saw and continuously thinning my ground, on the side. Grow them trees. (((o)))

crtreedude

Here in the tropics, it is very, very important to plant pioneer species in the sun, otherwise you get bushes - not logs. Once we have the early trees growing, we can plant the slow growing ones between.

What is very interesting is the slow growing trees often have huge roots systems after a few years if you plant them in shade / semi-shade. They are getting ready for an opening in the canopy. Once a hole appears, they will shoot up, 6,10 even 15 meters in a year. Pretty fascinating really.

You often find trees that look like seedlings in the forest that are really 20 or more years old - just waiting for the chance in the sun.

So, how did I end up here anyway?

wisconsitom

I agree with Mr. Beauchamp that what we really want to talk about is seral stages.....where are we at any point in time with reference to a given site, its history, what propagules were/are available for regeneration....what has been there.

Take the big white pine/hemlock stands that were logged in the 1800s and early 1900s.  These stands were roughly 400 years old.  But white pine is not necessarily the endpoint for many of these sites.  Rather, they would ultimately end up as mixed hardwood/hemlock stands.

So why were there these large areas of a mid-seral stage?  Evidently, as pointed out earlier, it just takes a huge disturbance to knock those stands down, or to burn them down, or to have them killed by disease, drought, insect attack....such that they begin to seem permanent.

Similarly, stands of species like white-cedar are very stable, but given a big enough push by some force, they too could be replaced by a later stage.  It just doesn't tend to happen much.

The early model of pioneer = shade-intolerant while "climax" = shade-tolerant and never the twain shall meet is too simple.

The general trend in the Great Lakes forest is the loss of yellow birch to a more shade-tolerant species-sugar maple.  I'd prefer the opposite, but there ya go.
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SwampDonkey

The only hardwood I planted as a reforestation tree (and not yard tree) was yellow birch. Timber companies here only want to plant spruce, very little else except a little jack pine or red pine. White pine is only planted because they put 1% or something like that in their containers when seeding for spruce. So might have 1 per 100 that is a white pine. But up here they don't have much chance.
"No amount of belief makes something a fact." James Randi

1 Thessalonians 5:21

2020 Polaris Ranger 570 to forward firewood, Husqvarna 555 XT Pro, Stihl FS560 clearing saw and continuously thinning my ground, on the side. Grow them trees. (((o)))

wisconsitom

I had to take deliberate action to grow good Norway spruce and white pine in weevil country.  I've mentioned this elsewhere and I've also mentioned the caveat that my acreage is small.  Big tracts?  Forget about what I'm about to say;

White pine weevil loves big, fat terminal buds of select conifers to lay its eggs.  The first half-way warm day of spring, mama white pine weevil is going to wake up in the duff layer and get right up to the tip of those white pines and especially Norway spruces, lay her eggs, and those larvae will hatch later, tunnel around and kill the terminal growth.  Lots of pine and spruce "bushes" can be so produced.

Well, I was so smart that I managed to plant thousands of these two species right next to each other!  As the trees grew rapidly in a good site, I began to see the drooped terminal growth and for a couple years, didn't even have the right insect in mind.  Hard to explain how stupid a man can be, but as a pro horticulturist, I was misdiagnosing my own problem.  Eventually, I got the right target, I got the correct info and control regimen, and now am able to grow great, single-leadered white pine and N. spruce.  

I go through the row in winter and prune out double tops, etc.  Basically, I am preparing for the next step.  Sometime typically in April, it will warm up into the 50's or so and it is time to get out with a synthetic pyrethroid insecticide with spreader/sticker.  I use benfithrin and recommend the same.  Be sure to get a formulation with that spreader/sticker.  Then, go down your rows of white pine and/or Norway spruce and spray the top leader and anything that looks like a leader, down to the first whorl of branches.  It's not so bad-you only are coating the tips of these trees.  The spreader/sticker keeps the material around along enough so that it is there when the larvae hatch.  Likely, adult females are affected by the material as well on their trip up the plant to lay eggs.  At least in my case, this has worked out very well.  You're never going to eradicate.  Just knock down the population is all that's needed.  My trees are doing great now and I think that after just a few more years of application, I will be out of that business as the trees reach heights at which the female weevil is no longer interested in attempting to lay eggs there.

Sorry for the off-topic bit.  The man-made forest I've planted there is heavy on these mid-seral-stage species.  But of course, I am controlling what grows where there.  We do seek to one day create legacy stands and have selected species that are roughly matched for longevity, this of course being far off in the future.  It seems most pine-family members as well as other non pine-family conifers like Thuja, etc. are in this category of plants that can and often do colonize open ground, but then if one were able to somehow go back three hundred years later, these same trees would still be there.  I would tend to lump these all into the category that can be pioneer, but then hang on for great lengths of time on a given site.  Long-term seral stages.  One in a series, but that "series" could be as long as centuries.
Ask me about hybrid larch!

SwampDonkey

Rust is bad here on pine and so isn't moose. :D The woods is full of ribies around here. ;) And rust will outright kill a pine, where the insect just damages it.
"No amount of belief makes something a fact." James Randi

1 Thessalonians 5:21

2020 Polaris Ranger 570 to forward firewood, Husqvarna 555 XT Pro, Stihl FS560 clearing saw and continuously thinning my ground, on the side. Grow them trees. (((o)))

wisconsitom

We can have rust-I take steps to limit-but no moose here in last oh, maybe hundred years!
Ask me about hybrid larch!

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