What is a 'climax forest'?

chain · October 27, 2011, 11:45:54 AM

What does the term 'climax' have to do with a forest?

Texas Ranger · October 27, 2011, 12:01:11 PM

It is the stable end results of site, soils, environment, climate, of the evolution of the site to the optimum plant and animal biome that can exist under those conditions. Sub-climax would be a biome that is held at a lower level by fire, mans usage, etc.

Ron Scott · October 27, 2011, 01:29:41 PM

From the SAF Dictionary of Forestry:

Climax

Ecology the culminating stage of plant succession for a given environment; the vegetation conceived as having reached a highly stable condition —note 1. some ecologists restrict the term to vegetation of mature sites and soils that they presume to have a high degree of permanence, others apply it to vegetation conceived to be stable only as long as the environment remains unchanged, or to vegetation that changes only in response to changes in climate or soil substrate that are slow relative to the rate of plant succession —note 2. Clements argued that, for a given region, there was only one true climax, i.e., stable vegetation on mesic sites determined by climate, and hence termed by him the climatic climax; sites with stable vegetation but influenced by factors other than climate received special names: preclimax (local unfavorable conditions preventing full vegetational complexity), postclimax (local favorable conditions permitting greater complexity), biotic climax (maintained by biotic factors), edaphic climax (maintained by soil factors) —see seral stage, subclimax, climax forestThis definition last updated 07/18/2008

Climax Forest

An ecological community that represents the culminating stage of a natural forest succession for its locality, i.e., for its environment This definition last updated 07/18/2008

SwampDonkey · October 27, 2011, 05:26:28 PM

It varies by soils and drainage or course. But on the moist well drained land the climax for our area is sugar maple, beech, yellow birch, hemlock, red spruce and white pine as these are long lived species. It will tend to be 70 % or more sugar maple. These sites are what get targeted for agriculture land clearing. On swampy ground with calcareous bedrock it is white cedar.

Ianab · October 27, 2011, 07:54:22 PM

It's especially noticeable with our local forest. The initial regeneration of the forest is nothing like it's eventual make-up.

If farmland is abandoned or neglected the first things that grows are species tolerant to full sunlight like gorse and manuka (weeds and scrub). These can take hold in pretty much any bare soil, or grass area.

They will only reach 10-20 feet, in as many years. Then they act as a nursery for the more delicate second stage trees. Rewerewa, tree ferns, mahoe, kamahi, lancewood etc will germinate below the scrub and eventually grow up through it and form a more permanent forest. But the true climax species are the ones that will only germinate under the sheltered forest. Rimu and Tawa etc, although delicate, are very shade tolerant. They grow in the full shade, can live as a seedling for 20+ years, and when one of the canopy trees naturally comes down, they are there to grow up through the resulting "light tunnel".

Eventually you can pretty much end up with a rimu / tawa only forest as they are pretty much the only trees able to regenerate in those conditions. This would be considered the "climax" forest, and exists as a steady system. Might take 500 years to get to that point, but after that, not much changes. Fire is not an issue in the rain forest, so things seldom "reset" and start again without a bulldozer, volcano, cyclone etc.

Ian

chain · October 27, 2011, 10:05:47 PM

Very interesting comments, I knew there was some controversy in defining the 'climax forest' as in ecologist vs. practical forestry definitions.

But why I asked is, my personal management goals of our forest. I try to take a hard look at each stand or compartment, short-leaf pine vs. red oak, white oak vs. maple, sweet gum. I will try to give an example of a natural progression. Let's take a bottom stand of Ozark timberland; this stand of nearly 90% red oak, a few red maple, hickory, a few white oak as the other 10%. Sometime back in the early 1980s nearly all red oak died, possibly a drouth began the die-off, various diseases set in. Now, nearly 30 years later a 90% stand of red maple stands as pole sized trees where the oaks once stood. Is this typical, in the progression of a climax forest or, will this new species eventually succumb to a more original species? Like, back to the future?

Ron Wenrich · October 28, 2011, 06:06:15 AM

Climax forests tend to be those that can sustain themselves by the amount of sunlight they need to germinate and to grow. The more intolerant species are those that are first in the forest progression. Those are usually called the pioneer species. Aspen and eastern red cedar are 2 of those that are found in my area. Pioneer species tend to have a shorter life span.

As the forest moves from seedling to sapling to poletimber and sawtimber, more tolerant species will take over the site. They germinate in more shade, then may hold in the understory until the overstory starts to die off or a disease or fire takes the forest to the next stage. You will see more disease and bug problems in monocultures, which is quite often what a pioneer forest is.

You may have several progressions of forests before you reach the climax stage. The most tolerant species in my area are hemlock, sugar maple, white oak and beech. The hemlock and beech have pretty well been weeded out as a species.

The more desirable trees from man's perspective tend to be those that are more in the middle range of tolerance. By varying the size of the openings in the forest, you can vary the species which will grow and thrive. If you clearcut, then you can grow those intolerant species. A seed tree cut will give more of the light seeded species needed for natural regeneration and be more intolerant in species. A shelterwood cut often takes out the understory while leaving the dominant species to regenerate. That is later removed and the new regeneration takes over. A constant thinning of sawtimber only trees will result in the more tolerant species.

In your case, the more tolerant red maple have been sitting in the understory and the overstory has died off. It may be the next step towards a climax forest, but it isn't at the climax stage. If nothing happens to knock the red maple off, the next stage may go to that 10% white oak that was there.

Diameter limit cutting is the predominant management strategy used by some foresters, many loggers and many landowners. That has resulted in the leading species in PA to be red maple. There's a good mixture of other species in the state, but red maple has been increasing due to cutting practices.