SOS Forests

Reminds me of the old psychoacoustic modeling used during the development of MPEG… psychoacoustic my ass! They should just say degraded sound quality. It’s like opthalamorectumosis – it’s not dangerous but it gives you a shitty outlook on life…

Repeat over and over, “I am not a zombie puppet,” until you receive further instructions.

An observation from my elkless elk hunt on the corn flakes ground cover of a dry time on the east side of the Cascades in the Transition Forest….

I got into a pile of lodgepole blowdown in the Wilderness….and in that stand, maybe a mile long and a half mile deep, there were some residual Shasta Firs, and maybe an Idaho white pine and a doug fir. The pine was a three footer with a viable top, having yet to be infected with blister rust. The others were 4 or 5 foot on the stump, and maybe 100′ tall. No reprod of their species under or around them. Singular survivors of a fire. And the new stand was lodgepole, at least 100 years old.

My guess, just a guess, is that when the old growth stand burned, the whole of the temperature regime changed, and absent the thermal cover of the older stand, only lodgepole could now utilize the burned area. The big old trees had enough water, and bountiful sunlight, but the temperatures are too cold in spring or too hot in summer for anything but lodgepole to germinate and grow there. I would take this to mean that it is colder, and has been colder, than when the Old Growth stand was established long ago.

I now expect you research foresters to tell me where my thinking is awry.

Erase the lodgepole in your mind’s eye and what do you see? An open, park-like stand of old trees. Based on the variation in old tree diameters, most likely uneven-aged. Where did that stand come from? What forest development pathway leads to open, park-like, uneven-aged, multi-species stands?

Answer: frequent, seasonal fire, largely anthropogenic. Lightning alone doesn’t do it. Wrong season, too infrequent. Only regular autumnal light burning gives rise to what in essence was a conifer savanna.

Then the burning stopped. The torch-bearers, the indigenous residents who set the frequent, seasonal fires were displaced from the locale. Not by a change in climate but by Euro-American emigrants and the Old World diseases they introduced.

In the absence of yearly burning the lodgepole pine seedlings, which were always germinating, were no longer killed by the autumn grass fires creeping under the old pines and firs. Those weak LP seedlings survived in the absence of regular fire and occupied the site.

Now, 100+ years later, two cohorts are present. The older cohort is really a collection of cohorts; each old tree is a cohort in itself. The younger cohort is even-aged, however.

That age structure is the classic, common, multicohort structure found across the West. The species may vary from landscape to landscape, but usually the older cohort is heavy to ponderosa, sugar, and/or white pines, with a contingent of Douglas-firs. The younger cohort is typically lodgepole, true firs, larches, and/or incense cedars; prolific seeders that produce weak seedlings prone to high mortality, especially in grass fires.

The climate of the 18th and 19th Century was no different than today’s climate, and no different than when the lodgepole thicket germinated. Then, as now, the winters were cold and the summers hot. Then, as now, summer drought was the dominant weather pattern. Then, as now, lightning struck irregularly but mostly in summer. It was not “climate change” that altered the forest development pathways, because the climate has not changed.

Human beings were essential players in the ancient forest development pathways. The old-growth forests of today were established by virtue of human tending of the landscape.

I realize that the Anthropogenic Fire Theory is not widely known, let alone understood. That’s why I call it the New Paradigm. But it is actually old knowledge that has been forgotten, not a new discovery. Be that as it may, frequent, seasonal, anthropogenic fire was the phenomenon that sculpted our forests for millennia.

Thank you, bear, for your sharp observation and excellent forest example. I know that you knew the answer all along. Hope I passed your test.

In support of bear bait’s observations and conclusions, I have seen similarly structured stands around here (S end of the Willamette) on the westside in high elevations: Stands of widely dispersed, large diameter Doug-fir poking out of a matrix of silver fir about 150-200 years old. When areas like this were clearcut (when we used to do such things) folks planted DF back since it was on the sites originally. Unfortunately in these high elevations (around 4500-5000′) the little DF saplings get squashed by the snow (these areas usually have a 4-6′ snowpack, and some years much more than that) and ultimately could not compete with the advance silver fire regen that was still on the site.

While those open forests of big trees may well have been created/maintained by conscious use of fire, the fact that DF does not now regenerate very well on these sites tells me that those 400-600 year old DF got started during a warmer, drier climate regime, or at least one that had smaller snowpacks than what we see now. Make sense?

Tim, the climate 400 to 600 years ago was not warmer and drier, so no, it does not make sense.

Look, the density of 400 to 600 year-old trees was about 10 stems per acre. That means a new tree became established on an acre only once in 40 to 60 years.

One tree per acre per half a century is not a very good success rate. Surely there were many more seedlings germinating every year than that. Yet the successful establishment rate was so low!

What was responsible that poor success? Was it deep snow? Summer drought? Heck no. We have those today and somehow tree seedlings survive. And at a much higher rate than one per 50 years. And true firs seem to dominate the seedling mix rather than Douglas-fir. There is no reason to believe it has ever been different than that.

No, there had to be another factor at play that limited regeneration success and selected the species mix. That factor was fire.

It had to be frequent fire, too, because infrequent fire would have allowed many seedlings to grow to survivor-hood or else wiped out whole stands, but that’s not what we see on the landscape. We see multi-cohort stands as described, that were once open and park-like with ~10 trees per acre, dominated by thick-barked, fire-resilient tree species. Only frequent fire would kill almost all the seedlings every year, and select for thick-barked species over thin-barked species.

There is other evidence. The old trees exhibit characteristics of open-grown trees: wide rings at the pith, large limb indicators near the ground, low height-diameter ratios, etc. They were not stand-grown trees; they were open-grown, wolfy, loner trees. The old trees bear multiple fire scars. Testimony of tribal elders and pioneer journals confirm the historical stand conditions and the Indian burning. Etc.

The climate has not changed, at least not significantly. The same species (DF, PP, SP, etc.) have been present for thousands of years according to pollen records, despite the Climatic Optimum of 9,000 years ago, the Medieval Warm Period, the Little Ice Age, and all the other historical climate perturbations. Our tree species are adapted to a wide variety of conditions, as evidenced by their geographic distribution today. Climate does not rule the roost. It is not an important factor, or at least, it is not as important as some people today wrongly conjecture.

Of course it’s not fair to conjecture on the history of a stand that one has never seen, in an area whose soil, topography, and associated species are only generally alluded to, but here goes.

Alternative hypothesis #1. The old-growth trees are not survivors of a fire at all, but rather isolated bastard growth, seeded by wayward birds or other means into the area when it was a grassland or brush field.

Regular burning in the area by local Indians kept these trees from seeding in amongst themselves for a hundred years or more.

Subsequent herds of sheep, cattle, and/or wild ungulates possibly kept seedlings from being established for a while after the regular burning stopped.

Meanwhile, given the absence of fire, lodgepole began spreading like slow motion wildfire throughout the area. In the subsequent absence of possible grazing, it quickly seeded in around the isolated conifers.

Because lodgepole seedling grow so quickly and densely, competing seedlings from the older conifers were readily out-competed for water, nutrients, and sunlight. Shaded out of existence.

Unless, of course, evidence of an earlier stand of burned trees still exists as snags, stumps, or carbon prisms in the soil.

Alternative hypothesis #2. Climate change.

Hypothesis #1 has tons of hard evidence to support it.

Hypothesis #2 has no evidence in support.

Moreover, Hypothesis #2 is not a forestry hypothesis. That is, climate change or not, nobody (with one exception*) has conjectured a hypothetical forest development pathway, absent anthropogenic fire, that might lead to multi-cohort stands.

In fact, typically Old Paradigmers deny that multi-cohort stands exist. They persist in calling stands “even-aged” when the facts on the ground are utterly contrary. Anybody who has actually aged the trees in ancient forests is forced to admit that a wide spread of tree ages is present.

*The one exception is Chad Oliver, author of Forest Stand Dynamics. He hypothesized that “stem exclusion” via competition naturally thinned dense stands into sparse stands. Then “stem reintroduction” resulted in a second wave of tree establishment. However, subsequent research by John Tappeiner, Nathan Poage, and others (such as myself) have found that the old trees in multi-cohort stands were open-grown. They were not stand-grown. They were always competition-free. And they are uneven-aged (many ages in the old cohort). Those “anomalies” throw a wrench into Oliver’s hypothesis.

Yes, but the old DF I am talking about there do not have a great range of ages. And wasn’t there a Climatic Maximum that ended about 600 years ago? I think I heard that the Vikings’ colonization Greenland ultimately failed when the warmer climate regime switched to the Little Ice Age - didn’t that happen around 1400? There have been climate fluctuations on that sort of time scale for a long time and one needs to take that cycle into consideration when talking about such long term matters. And by the way, some 4,600 years ago there was a significant (statistically speaking) amount of Oregon white oak pollen floating around the Willamette Pass area (as evidenced from sediment analysis at Gold Lake Bog). For that to happen, it had to be considerably warmer and drier than it is now.

I should also have mentioned above that species presence does not say much at all about species distribution. Sure, Doug-fir has been growing on the west coast of N America for millions of years, but the places it may have occupied at any given time may have varied considerably. Too bad we’ll never know for sure; how many spotted owls were there 5,000 years ago?

After 100,000 years of the Wisconsin Glaciation, the Holocene erupted rapidly about 11,500 years ago. That coincided with the Milankovich orbital solar maximum. Although there have been small ups and downs, global temperatures have been trending generally downwards for the last 9,000 years, when temps were about 5 degrees C warmer than now.

We are in a neo-glaciation stage. Another Ice Age glaciation is coming, just as they have arrived like clockwork for the last million+ years.

So yes, it was warmer earlier in the Holocene. Not necessarily drier though. Warmer global temps cause greater evaporation from the oceans which leads to more precipitation. During the depths of glaciations precipitation is minimal.

Re the distribution of Pseudotsuga: the genus is found from Mexico to Alaska and west to Japan and China. Pseudotsuga is the only genus in the Pinaceae family with 13 haploid chromosomes (all the rest have 12). That means Pseudotsuga is a freak, a mutant, and a super tree with survival powers greater than any other conifers.

Even so, during glaciations Douglas-fir was confined to refugia. It is not a tundra species. Pollen studies indicate that DF first spread into Washington about 11,500 years ago, after the ice sheets melted.

Ponderosa pine is first noted in local (Oregon) pollen cores about 9,000 years ago, and western red cedar about 6,000 years ago. Humanity, on the other hand, has a recorded presence in the region dating back at least 13,500 years ago, before the ice melted!

All that means that Gold Lake oak may have been (probably were) part of a human-modified landscape.

And the range of ages of the DF in the vicinity has not been fully explored, so I hesitate to confirm your estimate. There is a distinct 375 yo DF cohort in the Lava Lake area that could have arisen after disease epidemics wiped out local tribes and anthropogenic burning was halted temporarily. Interestingly, there is not a 375 yo cohort of other species, indicating that burning resumed and weeded out the thin-barked species.

That brings up an important aspect of a frequent fire regime: the presence of an age cohort indicates a period (perhaps a decade or longer) of no fires.

Many people think of cohorts of trees as arising after a fire, with the age of the trees indicating a fire date. But in a frequent fire regime it’s just the opposite. Tree ages indicate a break (hiatus) in the burning. Since frequent fire regimes were largely anthropogenic, the tree ages (hiatus ages) indicate that something happened to the residents that caused them to cease burning for a time. Tree ages thus hold anthropological clues.

Indeed, the presence of the younger cohort of lodgepole pines in bear bait’s stand is a sign of a change in human (cultural) impacts, not a change in climate.

All these points are interesting. I will do another post on forest development pathways and anthropogenic fire.