Forest for the ages

I worked in air quality, water quality, range, wildlife and forestry with the U.S. EPA, and the U.S Forest Service. I did that in Nevada and eastern Oregon for over 30 years. Over that period, it was natural to develop an abiding love for the island forests and woodlands of the interior. and a deep interest in their development since the last glaciation. There can be few places more welcoming on a blistering summer day than under the sun-filtered canopy of an old-growth Ponderosa pine forest, and nothing more sublimely elegant.

Old-growth Ponderosa pine

Old-growth Ponderosa pine

How did they get here and how are they doing? They’ve been around a long time, and there should be more big ones that there are. That’s too bad since the plate-like bark, half a foot thick and often outlined in a mosaic pattern of fire-hardened scars – is nearly impervious to any but the largest blazes. Properly managed, these old-growth forests are the best hedge we have against wildfire in this widespread ecosystem. Even in death, the searing heat they’ve experienced over their 300-500 year life-span can seal the trunks off from rot for the next 80-100 years. They are then resurrected as crucial habitat for all the cavity nesting animals. Those creatures can, in turn, play an important role in kick-starting the next forest stand.

I’ve come to feel that, with climate modification a growing planetary concern, the interior western forests offer a crucial reservoir of genetic diversity. If there’s any hope of coping with the changes which might result from a catastrophic shift in the climate regime, it resides in the gene pool of communities like these dryland forests.

Ponderosa Pine (Pinus Ponderosa) defines the margin of many interior forests in the western United States. It’s the most drought tolerant giant conifer in North America. The Lost Forest Research Natural Area, Central OregonPaleobotanists examining the fossil record have found evidence that, in the recent past, forests of Ponderosa have existed in many different configurations. Plant associations which have no current analogs can be found in that record, an indication that “Range shifts occurred that could not have been predicted ...” and that these shifts “…apparently led to anomalous species associations

The implications of this research are of major importance. They offer up some hope of coping with the changes in the variation of seasonal precipitation and temperature which will result from broad-scale climate modifications.

That’s because, from the fossil evidence mentioned above, we now know that the genes of these forest types represent a large reservoir of unexpressed diversity. This diversity provides a crucial hedge against climate change. It allows drought tolerant Ponderosa pine forests to adapt quickly to altered conditions. That’s happened many times in the past, that’s what this evidence tells us.

Unfortunately, this diversity has gone unacknowledged resulting in the failure of silvicultural theory on both public and private lands in the West. Foresters chose to “liquidate” stands of old-growth Ponderosa Pine in favor of what they promised would be faster growing stands of other conifers. The idea was to make more money off these new forests. But this attempt at forcing moderate to low-elevation sites to produce as if they were industrial forest plantations has failed. Insects, well-adapted to that same variation in climatic forcing, re-worked overstocked stands of drought-intolerant species, just as if there’d been a change in the climate.

The message is clear: at the forest margin, trees other than Ponderosa pine are a minor component, so Ponderosa is what should be there. But since they are slow-growing many of these stands cannot be economically cropped now or in the future. Selective cutting, with its much lower rate-of-return, should be the only way we remove trees from these forests. The fact is, these pine forests are much more valuable for their water, forage, recreation and soil stabilization potential than as poorly managed quasi-industrial croplands.

We need to to insure the health of these forests. In their genes they carry a message from a long-distant past, one that may help us find our way in a very uncertain future.

Hikers in old-growth Ponderosa pine, Flagstaff, AZ ~1900.

Hiking in old-growth Ponderosa pine, Flagstaff, AZ, ~1900

Running on climate time

I recently had a chance to watch a video recorded as part of the series on Adapting to Climate Change a course for land managers developed by the US Forest Service and it’s excellent. It brought to mind an article I wrote years ago, in 1994 to be exact though it wasn’t published till 1997 in the Fall issue of the late great Wild Earth.

It was inspired by the work that was done coring the Greenland ice sheet, a real eye opener for me. During the last glaciation the planet would regularly transition from an average temperature that’s a few degrees warmer than now to a few degrees cooler in as little as 10, and maybe fewer, years. You can get a hint of these gyrations from the chart shown below:

Temperature proxy from ice cores

Temperature proxy from ice cores for the last 140,000 years (Wikipedia).

That’s an almost incomprehensible shift in the planet’s energy budget and it would have had a dramatic effect on the climate and the vegetation everywhere. This has huge implications for everything we think we know about forest, grassland, and desert ecosystems in the West. Yet those implications have, to this day, barely been discussed.

Here’s one of them: the gene pool of our western conifers has to contain the necessary diversity to deal with rapid climate change and we need to incorporate that into our thinking. That’s not an excuse for doing nothing. The potential social impact alone is enormous. It’s simply a statement of fact.

Take Ponderosa pine as one example. In the Southwest it has such a tightly bound relationship with Abert’s squirrel, that the only thing that critter sleeps in is pine-needle beds, and just about the only thing it eats are Ponderosa pine seeds. When I mentioned this years ago to a British geneticist, he said that probably represented at least 10 million years of co-evolution. If Ponderosa’s been a part of the Western ecosystem that long, the species has surely been through dozens and dozens of episodes of rapid climate change. It’s still around (and it’s also fast on its metaphorical feet as evidence has shown) so it has the diversity to make it thorough those rapid shifts.

At the same time as the results were coming in from the ice-sheet corings, we were just coming out of a spruce budworm outbreak in the Blue Mountains of Oregon. The forests were making a remarkable recovery after that episode. But the reaction to the 8+ year outbreak was very revealing. It seemed to induce a form of insanity in otherwise intelligent people. The budworm was imbued with demonic powers, a satanic force out to do us in. This wasn’t science as I thought I new it. The only people who made any sense at the time were entomologists such as Boyd Wickman. He and the others in his research unit kept saying that outbreaks have a way of ending quite quickly, and that the forest can recover just as quickly when it does. Their voices were subdued and rational, and just about completely drowned out by calls to log everything in sight.

I’m a mathematician by training and it smacked of the sort of perjorative language that discipline was riven with before “negative” and “imaginary” numbers were put on a solid footing. It’s also the same sort of language I heard used about one of the most versatile hardwood species in the world, red alder, when I first moved to the NW in the late 70s. “Professional” foresters called it a weed and insisted it had to be poisoned out of existence. Later I found out that it had such a tightly-bound relationship with nitrogen-fixing bacteria that it might as well be a legume. It’s so valuable for rehabilitating logged over lands that it gets star billing in this amazing book, one of only two species (Neem is the other) that has more than a single page entry. That told me all I wanted to know. Forestry, at least at that time (1978), was certainly not a science and it seemed to me barely an art.

So I wrote the article in reaction to the coring of the ice-sheet, and the evidence I could see on my own at the end of the budworm outbreak. It started as a letter to a good friend, then later I expanded it as a piece for Wild Earth.

My own opinion is that the budworm and its host species are so tightly intertwined that they’re really not seperable when I think of the ecosystem. That’s even more true for the mountain pine beetle and Lodgepole pine. The current beetle 17+ million hectare outbreak, draped like a multi-colored cloak across the mountain forests of Alberta and British Columbia in Canada, is a very dramatic example of the phenomenon I outlined in my article: a false climate signal brought on by years of fire supression that leads to an eventual rebalancing of the system. In the case of Lodgepole, that’s probably exacerbated by real climate change driving the ecosystem the other way, northward along the Rocky Mountains.

These ideas now seem to be gaining currency and that’s long overdue.

Central Asia as Surrogate

Years ago, at the Forestry and Range Lab where I worked, we hosted Alexander Isaev, then Forest Minister of the old Soviet Union. He’d been appointed to the position because, as he told me through his interpreter, he’d “complained so much that Gorbachev said ‘you take the job'”. The very first thing I’d questioned him about was his impression of traveling through Oregon. He’d just flown in from the other side of the Cascades the previous evening. That thin strip of well-watered forest usually draws all the attention from visitors, especially the lush temperate rain-forest in the coastal mountains. A world-away from the dry interior, it edges its way southward along the Pacific Coast down from British Columbia, finally tapering to a width of of no more than a few miles populated by redwood stragglers tucked away on isolated mountain peaks and in the hidden canyons fingering into Mediterranean California. I was expecting he’d reflect on that world. Instead he paused for a few seconds and looked up and away, into his past it seems. When he woke that morning and looked out his window, he thought of his first posting as a young forester, to Samarkand.

That’s a clue, and a good one. Much of Central Asia has a similar climate to the American West. I remember eagerly leafing through Heinrich Walter’s Climate Diagram World Atlas many years ago (some of which have now found their way online), quickly locating analogs to the climate of the region we’d moved to in Northeast Oregon. These analogs included places like Van, Turkey and Tashkent, Uzbekistan.

The difference is that such a vast place has been host to any number of nomadic tribes roaming from Europe to Asia and back, a human wave of aggregate demand on the land that was just as vast in its effects. We’ve all heard the stories of ransack, rape, and pillage. Notice that those are all human-centered observations. What usually gets lost in the telling is the ecological history of the Eurasian landmass.

Any number of  dramatic mountains and highlands  should, and at one time did, host thickly forested montane ecosystems. Some, such as the Anatolian plateau, the Lebanon, and anti-Lebanon ranges, and the Zagros mountains have been deprived of most of their forest cover.  Too often that has meant the soil that held them in place and nourished them has vanished as well. First the superstructure of trees that ameliorated the above-ground climate and tempered the erosive force of water was removed. Then the substrate that acted not just as a physical prop, but which hosted the nutrients needed to feed the trees, and likely the micro-organisms needed to produce future forest stands as well, was carried off by wind and water.

Other mountain systems have been subjected to an ever-retreating treeline which has pushed those ecosystems further and further up their heights. The Caucasus, the Tien-Shan, and other spectacular ranges have seen their share of human activity and the impact has been significant.