Beware of “Mommie Dearest” Trees?

Mother of the Forest, Circumference 78 feet bark off. Mammoth Trees of Calaveras Co., CA. The New York Public Library.

This article by Jenn Bernstein and Justine Karst is worth a read.  You can sign up for Damage magazine for free.

After I was taught at a church gathering that Mother Tree was absolutely true stuff (and the gates of my own knowledge did not prevail against it), I decided to look further.

First.. extraordinary claims require extraordinary evidence.  There’s a genetic component to be a mother.  If not, if they are adopted children, then perhaps the less emotionally compelling term “nurse tree” is more accurate.   But if there is a genetic component, how does the Mother Tree know which ones are her seedlings?

Don’t you have to propose,  and test a mechanism before you make this claim?

This seems to be a feature of current scientific norms. In old science, we did experiments to understand mechanisms, and we used to say “correlation is not causation”.  In today’s science, we leave the mechanisms to be explored by someone else, if there’s funding, but long after major findings are trumpeted by the university communications office and then the popular press.

Second (and I think that this step is often skipped), imagine an experiment that would test this idea.  How many species? How many different ecosystems?  How would you design it?  How would you handle the mycological aspect?  Would you do it in pots (not real) or on a forest site (way too many variables)?  Would you transplant seedlings or seed directly? How long would you wait before making conclusions? If your mind boggles. then it’s time for:

Third, if someone is making extraordinary claims based on not exactly impressive evidence (say, the genetic aspects of this work, which I have reviewed), then the right thing to do, in my view, is to jointly design experiments to further test the claims , with all the key disciplines and with skeptics. The sense would be joint curiosity, not defense.  There is no place for, as we have seen with this research, university administrators dissing the intentions of skeptical scientists (which now includes me. Hint: I am a supporter of all scientists working in good faith, and obviously don’t have a COI).  It’s about mutually learning about the world.. or is it about institutional hegemony or ideology or a kind of scientific popularity contest? And as we have seen and described in this post, leaving large trees is not a new concept and seems to be BAU in many quarters, known as variable retention and originally thought to be good for wildlife.

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Mother Trees” are described as the biggest, oldest trees in a forest. The metaphor was introduced in 2016 by forest ecologist Dr. Suzanne Simard. Despite having both male and female organs, these trees were dubbed “mothers” due to what Simard perceived to be their mothering behavior. Through common mycorrhizal networks, formed when fungi physically connect roots of the same or different plant species, Mother Trees are said to share resources with their seedlings, directly assisting in the survival of their kin. The story goes as far as to say that when “Mother Trees—the majestic hubs at the center of forest communication, protection, and sentience—die, they pass their wisdom to their kin, generation after generation, sharing their knowledge of what helps and what harms, who is friend or foe, and how to adapt and survive in an ever-changing landscape.” In her book, Simard argues that this kind of nurturing and caring dynamic has been obscured by the historic dominance of forestry by men, who see competition instead of cooperation.

Simard’s promotion of Mother Trees in forest conservation has been recognized as “revolutionary” and “pioneering.” Her TED Talk “How Trees Talk to Each Other” has been viewed over 5 million times.

Despite the clear popularity of Simard’s portrayal of forest dynamics, there are three crucial problems with metaphors that naturalize the relationship between women and the environment. First, metaphors that relate to nature and gender have highly problematic implications for gender equality and cultural progress. Second, the Mother Tree metaphor provides little guidance in addressing today’s most pressing forest management challenges. And finally, fusing normative goals with scientific practice risks the distortion of science in deference to a self-proclaimed sense of moral authority.

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Challenging Mother Trees

Metaphors bridge the unknown with the known to clarify concepts and establish meaning. They’re a powerful literary device that emerges from uncertainty to connect with understandings when there is not yet more precise terminology. A tree’s relationship with common mycorrhizal networks has courted metaphors because of our limited understanding of how these tree-fungal networks function. Interactions among trees connected below ground have been likened to the Internet (“wood-wide web”), and given their potential ability to distribute resources within a forest community, they’ve even been cast in political terms (“socialism in soil”).

Despite the Mother Tree metaphor having cultural resonance, many of its claims are dubious, untested, inconclusive, and downright false. For example, core to the Mother Tree narrative is the idea that common mycorrhizal networks mediate belowground resource transfer, enabling the Mother Tree to help her seedlings survive. But whether common mycorrhizal networks actually function in this way has been disputed for 25 years. The narrative also implies that seedlings should be more abundant and grow better when closer to Mother Trees, but some researchers have concluded the opposite, at least for pine trees in boreal forests.

Recently, a number of critical commentaries have been published about the basic metaphor, calling into question the mechanisms purported to facilitate nurturing of seedlings by Mother Trees. In the most recent experiment to date, there was “no evidence of biologically significant carbon transfer between neighboring tree seedlings that shared fungi in common. Many in the forest management community have simply ignored the idea altogether.

And with good reason. Like all organisms, trees vary in how they respond to other species. They can be in competition with each other for water, light, and nutrients, depending on the characteristics of each forest ecosystem. These relationships vary significantly between climatic zone, forest composition, successional stage, and management regime. Uncertainty, context-dependence, and inconclusive results from this difficult-to-study system are left behind when mycorrhizal trees in a forest are conceptually morphed into Mother Trees. Might there be just as many Mommie Dearest Trees as Giving Trees?

Despite such gaps, the popular media has been credulously fascinated with Mother Trees. A National Geographic video depicts trees in old growth forests signaling distress to each other through a common mycorrhizal network. This idea is based on a single experiment done on seedlings grown in pots in a greenhouse—a far cry from an intact forest. The idea that dying Mother Trees send their resources through mycorrhizal networks to nearby seedlings has never been tested in a forest.

Nevertheless, the Mother Tree story has been embraced by media organizations such as BBC and PBS, resulting in children’s booksdocumentaries, and pushes to change forest management. It appears irrelevant to these communities that significant parts of the story are based on little to no peer-reviewed research.

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7 thoughts on “Beware of “Mommie Dearest” Trees?”

  1. Perhaps the larger lesson is that lots of important things are going on underground in forests. Root grafts, biological nitrogen fixation , mycorrhizae and a huge array of fungi, bacteria, insects and animals are functioning there and critical to forest health and productivity. They have often been ignored or neglected in forest management and conservation. In many forests, for example, carbon fixation and storage are limited by availability of soil nitrogen.

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  2. John, I think that we might be talking past each other.
    Many things go on underground. Some of them have been studied intensely for a long time (I actually got my in start (50 years ago) measuring root growth). Yes, washing seedlings off and measuring new root growth with a ruler.
    But folks have been thinking about forest soil biology since at least 1953. https://www.journals.uchicago.edu/doi/abs/10.1086/399309?journalCode=qrb

    Even before I got out of the reforestation biz the role of mycorrhizae was appreciated, at least to the extent that some folks did soil inoculation.

    So I wonder what specific practices you are thinking of that would not involve “ignoring or neglecting” those concerns.

    You mention “for example.. carbon fixation and storage are limited by availability of soil nitrogen”.. I relate this to my local forests in which “carbon fixation and storage are limited by” lack of water, presence of cold weather, and in some places very little soil development and moisture holding capacity.

    Like I said, I think we’re talking past each other, but I don’t know where you’re going with that.

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  3. Huh? I was reluctant in commenting because I thought this story was a joke of some kind; I’m more likely to believe in a miniature sleigh and eight tiny reindeer and a rabbit that hops down the bunny trail laying eggs, than this…..

    What about a divorce? Does the mommy tree and daddy tree split the kids? Since both sexes occur in the same tree does this account for a DEI target? What about a affair? If a true divorce occurs, who gets the alimony? Not that cheating sassafras, that’s for sure!!!!

    Color me even more skeptical than normal for this one….

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    • Ha, Jim, no the Mother Tree is is a Real Thing. And many earnest, well-meaning people believe all of it, including some of my church buddies.

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      • We Southern Baptists have not crossed that burden to bear, thankfully. I try to reside in the field of science, without the nemesis of evangelical angst…..🤠

        Or, we don’t cotton to that kind of talk…. 🤣

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  4. I read in the Journal Science, 35 or more years ago, that electron microscopy had revealed mycelia of some fungi invade nematodes to kill them for the nitrogen and other micronutrients in their bodies. The fungi were found in wood debris are their organic habitat. At the time I was selling mill sawdust to farmers who used the sawdust as confined livestock bedding, as mulch for berry fields and a weed control blanket. Those uses had replaced the use of sawdust as home heat fuel and sawdust furnaces. The mill sawdust production was taken as hog fuel by our wood chips for pulp market. We got fifty cents a unit, and about 15 units in a possum belly truck. $7.50 a truck load. Farmers had no access due to chip market and logistics of getting waste away from mills now that waste burning was no longer an option.

    I got $15 a unit from farmers. Our capacity to store sawdust was small and finite. So the farm trucks had to take 3 units minimum and had to be on site ready to receive at a time and date engraved in steel. No shows did not get another chance. A dairy would put someone in their truck and have that slot covered in an hour. Several good customers were blueberry farmers and prospective blueberry farmers stockpiling the sawdust to heat up and change sugars to whatever and have volume enough to bed a whole field.

    The mill closed a year after the Clinton Northwest Forest Plan went into practice. I went to work for a reforestation contractor. Then I found a job setting up and starting a blueberry farm, and to be the manager. Instead of fumigating the field pre planting, I saved those $2000 per acre and bought sawdust. Lots of it. We incorporated 40 units in 4 foot wide rows on 10 foot centers, and then mechanically spaded it into the soils about 18″ deep. 1995. I left the manager job in 2012. I gave my journal of every facet of horticultural practices, fertilizer and pesticide applications, rates, tractor speeds, gear, rpms, mix rates of water per ounce of pesticide. My daily weather and seasonal weather events. Total outline if followed the owner could run the farm himself. And he did. I was there in August and he is still harvesting ten tons or more per acre every year. All one variety on his acres and a late ripening low sugar variety. His market is baked goods as they can add sugar to be consistent. Too sweet and the fruit changes the outcome of the product. In the interim, another 60 units per acre cumulative has been added to the rows. Plants are on 30″ spacing in the row. All nutrients are delivered by variable speed pumping matching demand per drip emitter. Fertigation is ongoing all the growing season. And no diseases. No aphid spraying. Integrated pest management. Aphids get established so a majority of leaves have a small colony. Chemicals from aphids overwhelm the airshed and the predator base arrives somehow and in a week you cannot find any aphids; only exoskeletons. The aphids’ tip blighting makes the plant put out later and more fruit spurs. And no root diseases and I attribute that to vaccinium plants depend on fungi in decaying wood to save the root hairs from nematodes and thus no need for nematocides. Sawdust takes care of that. Just like it does for the huckleberry seed that started a plant in the red rot of the fire killed doug fir that has lost its top to rot and wind, as the decomposition of that bole is red rot and wind force blowing segments over from the top down, especially when humidity drops to single digits in summer heat waves and the cohesion of molecular water holding it all together is lost.
    Not even the long roots of the huckleberry plant running down the sap wood wrapper of the snag no longer can hold it upright.

    I created a blueberry farm with zero ag background, only forestry learned by observation. I used the symbiosis of native vegetation and a chance reading of an article in the Journal Science on electron miscopy and nematodes predated by fungi to mimic forest conditions to harvest ten tons of blues per acre since 2000. No aging planting losing vitality. The owner continues to replace decomposed sawdust with new from a small stockpile.

    The absolute threat to his farm is the ever decreasing number of sawmills and the ever increasing losses of private timber and timberlands production to federal fire trespass from wilderness, roadless, and all other “protected from logging” federal land management. The lost synergies of supplemental logs from federal forests is depleting the ability to use fire killed timber, and the advent of new 1000 hour fuels for the next iteration of fire, as “unplanned ignitions” as an opportunity for PODs and their use to foist “Prescribed fire opportunities presented by unplanned ignitions.” End runs around laws are the real threat to our Democracy.

    Reply

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