Science Friday: “There may never be a single, widely accepted definition of old growth”—Tom Spies

Old growth longleaf pine forest

Some of us feel like we are revisiting the past.  Like I said, the mid-90’s there was a whole lot of defining going on.

I picked out this Science Finding  from the Pacific Northwest Station ( nice work PNW!) because I think the authors did a good job of summarizing the definition quandary . It’s from 2003, twenty years ago, now. I thought “uh-oh” when I read the first sentence.

Not all forests with old trees are scientifically defined as old growth. Among those that are, the variations are so striking that multiple definitions of old-growth forests are needed, even when the discussion is restricted to Pacific coast old-growth forests from southwestern Oregon to southwestern British Columbia.

What is an old-growth forest?
The question is not as simple as it may seem. The term “old growth” came from foresters in the early days of logging. In the 1970s research ecologists began using the term to describe forests at least 150 years old that developed a complex structure characterized by large, live and dead trees; distinctive habitats; and a diverse group of plants, fungi, and animals.

Environmental groups use the term “old growth” to describe forests with large, old trees and no clearly visible human influences. Many forest scientists do not see the absence of human activity as a necessary criterion for old-growth, but there is no consensus on this in the scientific community. This publication focuses on a scientific perspective of old-growth forests; however, this viewpoint is not the only possible one.

Recently, researchers and managers from Oregon, Washington, and British Columbia held a workshop on the development of old-growth forests in the region from southwestern Oregon to southwestern British Columbia. The group looked at what scientists have learned since the first major publication on ecological characteristics of old-growth forests in 1981. They focused on coastal Douglas-fir forests, but also included closely associated types such as western hemlock and Sitka spruce forests. “Coastal” included the area from the Pacific Ocean to the crest of the Cascade Range.

By using new technologies such as canopy cranes and laser scanning, scientists are learning much about canopy complexity and development in old-growth forests.
Of many challenging topics on the 3-day agenda, the question of definitions was the first one the group discussed. Many forestry textbooks lump all old-growth forests into one stage of forest development. Most scientists now agree, though, that the term “old-growth forests” actually includes forests in many stages of development, and forests that differ widely in character with age, geographic location, and disturbance history. Even within the specified geographic area, no one definition represents the full diversity of old-growth ecosystems.

Probably no single definition of old-growth forests and their values will ever exist.
“There may never be a single, widely accepted definition of old growth—there are just too many strong opinions from different perspectives including forest ecology, wildlife ecology, recreation, spirituality, economics, sociology,” says Tom Spies, research forest ecologist for PNW Research Station.

Spies and Jerry Franklin, University of Washington professor, developed a generic definition of old-growth forests in 1989 for the Forest Service. The definition reads, in part: “Old growth forests are ecosystems distinguished by old trees and related structural attributes…that may include tree size, accumulations of large dead woody material, number of canopy layers, species composition, and ecosystem function.” Most scientists would now include vertical and horizontal diversity in tree canopy as an important attribute.

This definition of old growth is widely accepted but too general for forest inventory or planning. Most scientists at the workshop thought that multiple definitions of old growth are needed for the diversity of forest types within the region.  Also, they thought, old-growth definitions should be finetuned to the inherent patterns and dynamics of the forest landscape mosaic of an area. “At best, we thought it may be possible to converge on a small set of definitions for inventory or mapping purposes,” Spies says.

Even so, when these definitions are applied, some old forests might be just one large tree per acre below the required minimum or have too few large, down logs, and thus might not meet a rigid definition. “The boundaries of what defines old-growth forests are a lot fuzzier than we’d like,” Spies explains. “Some young forests have elements of old growth, and old growth often has patches of young forest. Where fire was common in the past, the dominant trees have a wide range of ages.” In the end, he comments, “Because we deal with complex ecosystems, we have to be comfortable with flexible terms and some ambiguity.”

My bold.

With regard to “accumulations of large dead woody material, number of canopy layers, species composition, and ecosystem function. Most scientists would now include vertical and horizontal diversity in tree canopy as an important attribute.” But fire-adapted forests often don’t have accumulations of dead woody material, number of canopy layers, horizontal diversity, as in the longleaf photo above.
Seems like a national definition would be a heavy, and perhaps unnecessary and unhelpful lift.

I’ll going to write the Sierra Club folks and ask (1) if they have a definition and (2) what projects they know of with this problem.  I’ll report back. Meanwhile thanks to Susan Jane for listing a project where old growth has been called out as an issue.  I’ve got another one to discuss next week, and please put any others in the comments.

Additional note: reading the Campaign it actually says “We are calling on the Biden Administration to enact a strong, lasting rule that protects mature trees and forest stands from logging across federal lands as a cornerstone of US climate policy. ” That would seem to place them at odds with the “cutting big to protect bigger” we’ve been discussing.

7 thoughts on “Science Friday: “There may never be a single, widely accepted definition of old growth”—Tom Spies”

  1. Talk about revisiting the past, why not go back to the 80’s, thats when trying to define “Old Growth” started in R6, Westside OR at least. Spies and Franklin, along with John Teply from R6 RO and others hatched a plan called MOMS (Mature & Overmature Survey) that was designed to “inventory” what most agreed at the time were old growth stands of timber. RO provided a budget of 2-3 million dollars and decided the Willamette NF was a good place to start.
    A few of us field going Forester/Tech types were pulled together to go through district filing cabinets, do some photo interp, and come up with candidate stands. We then took the whole dog & pony show (PNW, RO, and Forest folks) to some field sites to validate our assumptions. Were the big trees big and old enough? Did the stand display multiple stories and tree species? Was there standing as well as down and dead woody material? What about slope and aspect and elevation? What plant communities were present? After a few days and some good lunchtime debates we came up with what and how to measure for our inventory plot design. It was decided we would select around 200 stands throughout the forest and delineate a spot on the ground that could be found on an aerial photo. After we installed a few plots, it was decided that field plot installation would be contracted, and we would inspect for accuracy. I personally bored about a thousand trees with my 4″ coring tool(actually went thru 3 of them)
    Long story short, this survey type was carried to three other westside forests, did we decide on an agreed upon definition of “Old Growth”? The debate goes on!

    Reply
    • Cool story, Tom.

      Circa 1988, I was tasked with figuring out which Region 6 planned timber sales would log old-growth forests, aka northern spotted owl habitat. Required visiting each district office in western OR and WA to read through the shelf stock sale documents; about a day in each location. I had often to resort to “Large sawlog” as a proxy for old-growth because there were no other data, maps, or habitat descriptions in the timber sale project files.

      The result of this labor, a list of several hundred timber sales, became the motion for preliminary injunction in Judge Dwyer’s spotted owl case.

      Reply
      • Andy, the result of my old growth survey work finally got me a perm FS timber sale planning job on the Siuslaw NF after 13 years as a temp. After about 6 months Judge Dwyer’s injunction hit, and mine and others planning work was put on hold. Within a year our district timber dept. (Waldport RD) was disbanded. Most of our workforce was sent elsewhere or RIF’d. I managed to stick around on the Forest for awhile by feeding spotted owls at night, counting marbled murrellets, butterflys, and frogs, as well as trapping mountain beavers. Ultimately I learned to map spotted owl habitat, became a GIS analyst, moved to R3 to map another species of spotted owl habitat.

        Reply
  2. As I noted on a separate discussion, “old-growth” is a logger’s term going back to the early 1900s, and maybe earlier, that has to do more with a tree’s size and appearance — and marketability — than it does with age. Old-growth Douglas fir were called “yellow fir” in early cruises, and were typically 250+ years of age on the coast, and 300+ years in the Cascades.

    The 1945-1947 Weyerhaeuser Coos County study set the age at 191 years. Then the forestry professors began defining the term in the 1980s and making up entirely new criteria (Jerry Franklin) to define this condition. I hate rote memorization, maybe because I’m really bad at it, but Tom Spies came to one of my forestry classes around 1990 and encouraged everyone to remember the phrase that the goal of old-growth preservation was to produce a “non-declining, even-flow, naturally functioning ecosystem.” I have never forgotten those words.

    During the class I pointed out that in my travels and significant time spent in the woods, I had never heard or seen such a condition. Where is this happening, if at all? And why was it being presented as some kind of ideal? My comments were quickly glossed over, but my questions remain the same. No idea why people are pointedly excluded from this — and most other — definitions of “naturally functioning.” Or why it is perceived as a desirable result of management.

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  3. I agree with Dr. Zybach. The US Dept of Justice has civil attorney teams to gain damages for fire caused by ignition from private land. One of the losses they have gained in litigation is compensation for is “loss of grandeur of the landscape.” Beauty contest? Or art, as in is the forest a Picasso, Marin, or Warhol? Or an elephant scribbling with paper and trunk armed with a brush and paint? No value for “old growth” has been established in litigation because it can’t be. But the whole landscape can be valued. Where do snags and dead forests for miles exist in the “grandeur of the landscape?” Who is the arbiter of “grandeur?” How do you lose that grandeur? When reproduction grows higher than the viewpoint and you can no longer see the landscape, does it have grandeur? That is this whole argument.

    Forests appear to have a constantly changing age, and there is no Franklin constant or even consistency as every day the forest is older until some dramatic event erases the forest and the process of renewal begins anew. If that were NOT the “constant”, what would be there now after cyclonic storms, landscape total fire, and total stand removal by beetles the size of a small grain of rice or the behemoth machinery of ClearCutter Logging, Inc? Always, unless the Olsens used the clear land to make their farm, or Sinclair Lewis painted the word picture of it now being “Main Street.” Or was that “It Can’t Happen Here?”

    When you live and can’t keep people from killing each other daily, hourly, and you see what a pandemic looks like and the power it has to institute change, how do we actually think that we can define where trees grow and how, and still have metes and bounds, litigation and some cockamamy idea that you can actually “preserve” forests when all that we know is that they are absolutely dependent upon change to exist. Hence, in my mind, “old growth” is not a definition of a dedicated tract of trees, but the description of one tree based on its size and species, and what to expect from that tree in terms of useful materials to create products for continuance of the communities of mankind. All else is some fraction of the “grandeur of the landscape” and that is always changing. As I drove to Santiam Pass to ski last wednesday, the former grandeur of that drive has been seriously degraded by conflagration. The “Opal Creek Wilderness” had a 35 year life as “protected” wilderness, and now has the grandeur of Stalingrad circa 1944.

    Often not mentioned because of the deflection from the monetary needs of NGOs serially litigating to “protect” the forests as intact entities to grow fuel and burn, is recreational marijuana and the clandestine use of “protected” forests to provide water and sunlight in isolated security from discovery, to grow a crop to harvest and then abandon the site, leaving behind months of garbage and the tools of weed growing in the wilderness. Unfortunately, anticoagulant broadcast baits to kill plant eating rodents are part of the leavings, and now we face the issue of ESA listing of Pacific fishers, Humboldt Martens, and zero Northern Spotted Owl recovery. All now proven to be victims of illegal pesticides, not logging. 3500 Barred owls shot in a government/timberlands owners project to see if “invasive” Barred owl removal would result in NSO reoccupation of former territory. Remember territory and territorial in the description of the critters extirpated by cartel and others illegal weed growth sites. 3500 autopsied Barred owls revealed 42% had residue from anticoagulants. These are not owls taken in farm land. Not owls from town where rats are a problem. These are owls from behind locked gates and from wilderness and roadless areas. How and why are they compromised by illegal pesticides? Likely, by illegal weed grow sites and the use of poisons to kill plant eating rodents. And those rodents, poisoned, are struggling to live and easy prey for the animals now of concern. Only 12 spotted owls were in being held frozen when someone asked if they could be examined for pesticide residue, and 11 of 12 had anticoagulant residue. Cause of death was never sought. They were just “found” dead and turned over to authorities.

    All of which brings to mind the question of “what is an old growth forest” and where does systemic poisoning by clandestine users of the protected forests fall in the discussion? You know that to grow weed you need sun. That is not there in young forests. You need sparsely scattered trees and openings. And water. And fertilizers and pesticides. What do those do to the water used? To the soils and immediate area? How is plastic drip hoses and emitters, food packaging, and the detritus of human occupation for several months ensure “untrammeled by the hand of man” in the protected from logging “old growth” forests? Limited camping now. Permits to day hike. The issue of protection is not to protect the forests and landscapes, but to limit or deny human use for that is a bigger benefit to mankind.

    Is there an old growth forest if you are denied access to witness it? And how would the layman know if she or he were in an “old growth” forest is there is no definition of how large or small one can be? My lifetime experience as a timber buyer is that the “mosaic” of vegetative types the Feds regale us with when describing how “benign” the fire they are reporting is, and how it is skipping areas and burning others, only to report a week later that “Hot Shot crews are burning out islands of fuel to better protect the fire lines.” Double talk and old growth forest is the same. It is what it has to be to further the litigation against USFS and other land managers. The private timberlands have been forced by taxation and investment returns to be in short 40 year or less harvest cycles to serve the imperiled housing market that is further and further out of reach of Joe Sixpack and Jose Nuevo. Meanwhile, the “forest reserves” burn and are not salvage logged, as we cannot “Mug a burn victim.” Andy has never investigated the medical processes used to heal a burn victim. IT is not without pain and suffering and tearing out old burnt tissue to build anew. Bad analogy for self serving narcissism.

    Old growth forests is an idea. Likely not a reality. Not when you are also looking at successional understory to maturity and death, and replacement, all while the old pines and firs, cedars continue to grow and age because they are in the right spot and have the size and ability to hog water and sunlight. Luck. Random luck and serendipity. Over a long time.

    I would note, because it is important to all of those interested in “saving” old growth, that Randy Moore, 14 years as Regional Forester for Region 5, was promoted by President Biden to Chief of the USFS, in June of 2021. IN the four months following his appointment, Region 5 had its worst fire season ever. Whole rural villages were consumed. CA had its first million acre fire. And more than 20% of ALL the Sequoias in the Sierras OVER 4 feet in diameter breast high were killed. More will likely die this year due to the loss of green limbs and needles needed to get water to the existing tissue.

    You can go to the USFS Chief’s Office to see the video of his inaugural speech which was not about science and protecting existing forests. Old Growth forests is a political issue, and the science is not settled. But CRT and equity and equality are. Evidently, the way to protect forests is through thoroughly structured human resource management that is by design a protection amorphous social welfare goals and hopefully, someday, a stand of trees and a few species of critters with perilous population deficiencies. I won’t hold my breath. Not when the pot heads who “saved the forests from industrial pesticide spraying” continue to kill charismatic wildlife with directed use of rodenticides with cascade killing results. Not when illegal water diversions kill young coho salmon and steelhead. Not when progressive legalize drug use and then take no responsibility for expanded demand that is met by criminal illegal use of publics lands with zero enforcement and investigation, all to avoid permits, fees and taxes, and thus able to undercut the market and drive the weed to other states to sell it. More permitted weed in Oregon than the legal market buys by a factor of TEN. Where does the 90% go? Where are the “water masters” from State Water Resources Board? Where are State Police? OLCC investigators with marijuana jurisdiction? All that “protected” forests and land and all we get from it is fire and poisoned wildlife. $680,000,000 private contracts awarded to Oregon fire suppression companies this month by USFS and BLM. Private landowners form fire protection districts and pay for insurance and for State fire protection. Have for decades. Build Back Better is paying for “suppression”, not protection or proactive fire prevention. There is a difference. Not that you would notice. Only because fuel removal does not meet the NGO of Green goals. Worse, the fire contractors are not Union. I bet they will be in two years. And dues to pay for political campaigns for progressive left candidates.

    You protect trees from fire by putting out the fires asap. To do that today is heresy. Funny, when you trust the heretics more than your elected officials.

    Find the components of “grandeur of the landscape” and you can then define “old growth” and still you won’t be able to pin down trees and forests that are mostly dead before age 80, and burned by age 120. Maybe “old growth” is “holocaust survivor” Doug Fir, his cohabitation partners Thuja, Tsuga and brother Pinus. Abies is away at Yeshiva. Alnus is racing young Doug Fir’s children. All are survivors or the children of survivors of past fire. All are saddened by the loss of so many of the aged Sequoia family in the 2021 fires. The good news is that of the whole Sequoia outfit, they only lost about 3% of the trees. But losing so many of the oldsters of size, over 20%, is painful. The protectors of our wild heritage failed us, but still get promoted. Why we so respect government. Laughingly.

    Reply
  4. I’m surprised Sharon didn’t launch into her “construct” criticisms because “old growth” is definitely that. It’s not what old growth is but what it does. Pick what function you want old growth to perform and you can define what characteristics it has so that it can be identified. But maybe it’s simpler than that – why not just protect whatever is rare and at-risk about old growth, however anyone chooses to define it?

    In Forest Service planning recently, it has mostly been about whether a stand (is that still a thing?) fits into a structure class that we have historic data about so that we can come up with a desired condition based on the natural range of variation. That’s a mappable planning proxy for whatever functions (especially species viability) the oldest forests have provided to their ecosystems. However, this desired condition is a pretty blunt tool, and could/should be supplemented with other direction/restrictions based on characteristics that could be identified based on site examination prior to any management.

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