An Old-Growth Biotic Pump Enviro Show

Listen to the conversation — or read the full transcript — with Massachusetts forest activists Don Ogden and Glen Ayers, hosts of the Enviro Show podcast. Followed by a list of biotic pump interviews.

In 2023, we attended the Eastern Old-Growth Forest Conference in Moultonborough, New Hampshire. I made a joint presentation with Prof. Susan Masino, co-author of the proforestation concept, on Forests and Global Well-Being. There was also a session on Climate Implications, which touched on two topics: carbon storage and impacts of climate change on the forests.

Biotic Pump and Biotic Regulation research explores a distinct and complementary perspective: how natural forests contribute to climate and environmental resilience by regulating the hydrological cycle. During our visit, we also learned about remarkable community efforts in forest preservation, such as Save Massachusets Forests and Restore: The North Woods.

So when Glen Ayers and Don Ogden — hosts of the Enviro Show and long-time supporters of forest preservation in Massachusetts and beyond — invited me to speak about the biotic pump, I was happy to accept.

Please listen to the podcast above or read the slightly edited transcript below. At the end of this post, I discuss what was the most difficult part of the interview. I also list several other interviews from the past five years discussing the biotic pump and biotic regulation more broadly.

Introduction

Glen: How about a Quote of the Week?

Don: All right. This one I think is fitting for our show.

Those who contemplate the beauty of the earth find reserves of strength that will endure as long as life lasts. There is symbolic as well as actual beauty in the migration of the birds, the ebb and flow of the tides, the folded bud ready for the spring. There is something infinitely healing in the repeated refrains of nature—the assurance that dawn comes after night, and spring after winter.

And that’s a Rachel Carson quote [from The Sense of Wonder].

Glen: Rachel Carson, really a great poetic writer, if you’ve never read any of her books, and she has several great books besides Silent Spring. Very beautiful, eloquent writing.

Don: I think this brings us to our interview, Glen.

Glen: Yes, our interview with Anastassia, who explains some of these concepts behind forest protection, having to do with the need to protect large areas of forest, because forests actually regulate the global climate.

And this concept of the biotic pump is a big part of that.

So let’s hear from Anastassia and I hope you find this interesting.

Today on the Enviro Show, we are joined by Anastassia Makarieva, who is joining us amazingly from Russia. And we found out about Anastassia from watching a video, a YouTube video about forests and this concept of the biotic pump.

And I don’t want to try to explain that, Anastassia, because this concept is kind of mind-blowing for us.

And we’re forest activists here in the United States.

But if you would introduce yourself a little bit, tell us about you and then tell us about this idea of how the forests act to essentially create the climate or create the environment. The self-sustaining environment.

Anastassia: Thank you, Glen.

First of all, thank you for the invitation. It is a pleasure to be here and to share my knowledge with your listeners who I know are as concerned or maybe even more deeply concerned than me about how to preserve natural forests, which is our common heritage, independent of where they are.

So about myself, I work in the theoretical physics division in a research institute in St. Petersburg, Russia. So I’m a physicist, but historically my work was devoted to investigating the mechanisms, both physical and ecological, by which natural ecosystems do indeed create and maintain a favorable environment — the processes by which life keeps our planet habitable.

The Water Problem

And as we live on land, for us, I mean for all living creatures who inhabit land, of primary importance is the water cycle.

The water cycle consists of several processes.

It is precipitation. So we get some liquid water or solid water from the skies.

It is river runoff. So part of this moisture drains away to the ocean.

And we also have an invisible process, but which is very, very important.

And this process is evaporation.

Everybody knows about evaporation.

If we have a saucer with water and leave it in our kitchen, then we come back and see that there is less water or no water at all.

It is evaporation.

But there is a more important, ecologically or, as we say, biotically mediated process, which is called transpiration.

And it is ensured by green creatures, green things, by plants.

And it consists in the following.

When green leaves open those tiny holes — those tiny openings called stomata — to catch CO₂ molecules, because they need CO₂ to produce food for the rest of the biosphere, at that moment the moist inner milieu of the leaf opens, and huge amounts of moisture are emitted into the atmosphere. In fact, for every CO₂ molecule fixed, hundreds of water molecules can leave the plant.

And so we have these three processes, precipitation, river runoff and evaporation and transpiration, the latter two sometimes are combined into one term, evapotranspiration [even if such a combination is not totally legitimate].

And what’s the problem that life has solved?

If we think on a large scale and imagine a moment in the history of our planet when there was still no life on land — and then it began to rise from the ocean and had these barren continents to conquer, so to speak — how did life manage to solve this water problem?

And what is the problem?

As land is elevated above the ocean, whatever water you store — for example, in soil — drains back to the ocean under gravity.

So it cannot be fully recycled.

It leaks.

And it leaks very quickly.

One of the key numbers modern people should bear in mind is how much water we actually have. People don’t know.

For example, if there were no import of moisture from the ocean, how long would it take for rivers to drain all available water from the land?

People can’t even guess.

But in fact, it’s just a few years.

We are not talking about very deep, ancient water — but about the water that is easily available.

So it is a very transient store.

The problem life was solving, then, was how to ensure the transport of moisture back from the ocean.

And that’s why, when we turn to the water cycle, our question was: how do natural ecosystems — and forests in particular — influence the water cycle in ways that make it sustainable?

The Water Solution

And it turns out that the answer is both very elegant and, honestly, mind-blowing, because water vapor in Earth’s atmosphere has a remarkable property.

It is a condensable gas.

So if we have enough moisture at the surface, and this moisture rises, it cools.

We know that if we go up into the mountains, the air gets colder and colder.

So when air rises, it cools, and water vapor condenses.

When it condenses and precipitates, there is now less mass in the atmospheric column.

As the mass decreases, air pressure drops.

And when pressure drops and an area of low pressure forms, it pulls in air from adjacent regions.

If we consider land and ocean, this low-pressure area will draw moist air from the ocean.

So if forests are able to keep the atmosphere over land moist, they sustain this process of condensation and precipitation.

This, in turn, draws in moist oceanic air, which rises, precipitates, and continues the cycle.

And this inflow compensates for the continuous loss of liquid water that occurs through rivers.

So how can we view this in everyday terms?

I sometimes compare it to an investment.

The forest has capital: soil moisture. It is a very important stock of a precious substance — water.

The forest transpires from this stock. It takes resources from this capital and sends them into the atmosphere.

Then, in the atmosphere, condensation and precipitation occur.

And there is an arrival of moist air from the ocean that compensates for this investment, rewards it, and also offsets the loss of capital through river runoff — which can be compared to inflation.

If the forest does nothing and simply tries to preserve its capital, it will disappear anyway. It will be eaten up by “inflation,” because soil moisture will drain back to the ocean.

But the forest is “wise” — and I put this in quotes, because there is nothing mystical about the process. It is physically transparent.

By transpiring moisture into the atmosphere, the forest changes atmospheric dynamics.

And this dynamic helps the forest sustain the water cycle and remain viable in water.

That’s how it works.

The Old-Growth Water Competence

Don: Anastassia, this is Don. I do have a question. Can you explain — and this is explained, of course, in the video that brought you to our attention — how old-growth forests move water better than, say, young forests?

Anastassia: Yes, this is a very, very important question.

You see, this moisture transport involves a complex set of processes, many of which include positive feedbacks.

For example, suppose the atmosphere is very dry, far from the dew point. If the forest transpires into this dry atmosphere, but condensation does not occur because it is too dry, then all the moisture the forest has “spent” will simply be blown away by the wind.

So this investment, so to speak, will be totally lost, because there will be no condensation, no precipitation, and no moisture inflow.

It is therefore important for the forest to transpire the right amount of moisture at the right time.

If we speak about old-growth, well-developed forest ecosystems that have evolved in a particular region and are well suited to its geophysical conditions, they do this properly.

Such forests transpire when the efficiency of the resulting moisture import will be greatest, and they avoid losing moisture.

But naturally, forests experience periods of disturbance — for example, fires or windthrow.

Even without human impact, we know that on such disturbed sites natural succession occurs. The ecosystem has the capacity to self-restore.

If there is a disturbance, non-random processes take place that gradually recover both the environment and the ecosystem.

However, during this process of self-recovery, the ecosystem is unable to regulate external conditions as efficiently as it can when undisturbed. Its resources are focused on recovery.

For example, early successional plants — herbs or grasses — transpire less than trees in an undisturbed forest.

So a recovering ecosystem, and the young forest that forms, exist at the expense of the moisture transport ensured by the old-growth forest that still surrounds the disturbed area.

But today, forests have been disturbed to a very large degree. Essentially everywhere we see disturbances.

There is no proper regulation of the water cycle.

That is why early successional, recovering forests — or tree plantations, which is another story — are unable to regulate the water cycle effectively.

Evolutionarily, disturbed areas were usually a minority. They did not need the full capacity to regulate the water cycle efficiently.

One specific mechanism present in old-growth forests and absent in younger stands is the so-called under-canopy temperature inversion.

When we have a closed canopy with tall, large trees, sunlight is absorbed in the canopy, and the canopy becomes warmer than the surface.

So we have relatively cool air near the ground and warmer air in the canopy.

Because cool air does not rise, there is no spontaneous loss of soil moisture.

Soil moisture remains under the control of transpiration. It is used for transpiration and not wasted.

For example, if there is wind, it could otherwise be blown away — but under these conditions, this does not happen.

Fires follow logging

When we disturb the old-growth canopy — for example, replacing it with shorter, more scattered trees — we increase wind speed.

More importantly, we remove this temperature inversion.

Now the land, no longer protected by green leaves from sunlight, becomes the warmest layer in the vertical profile.

Soil moisture then evaporates — not through transpiration, but through direct evaporation — into stronger winds.

This depletes the ecosystem of moisture.

That is why fires often follow logging.

This disruption of the local water cycle depletes local water stores in a young, fragile ecosystem that is trying to recover from disturbance.

When we log — even selectively, thinking we remove wood so that it does not burn — we disturb the water cycle so strongly that flammability actually increases.

Recent global studies show that ecosystem vulnerability to drought correlates with the degree of disturbance.

The more we disturb forest ecosystems through logging, the less capacity they have to withstand drought.

But this — temperature inversion and increased wind speed — is only one aspect of a very complex set of processes that constitute the biotic pump and, more generally, the regulation of the water cycle by forests.

Another important aspect is temperature regulation through cloud formation via biogenic cloud condensation nuclei.

This capacity is also compromised in disturbed ecosystems.

So there are many aspects to this.

Landscape Trap

Glen: I just want to say we’re talking with Anastassia Makareva, the co-originator of the concept of the biotic pump. And I want to give you a real-life example that I experienced when I lived in Colorado, in the high-elevation areas of the Rocky Mountains.

I’m talking about elevations above 10,000 feet.

The U.S. Forest Service had gone in there in the 1960s and logged extensive areas of old growth.

When I lived there in 1990, those areas still had not grown back into forests — more than 30 years later.

In fact, the Forest Service had replanted those areas at least three or four times.

The young trees they planted died. They replanted every couple of years — and they kept dying.

If you look on Google Earth now, you can still see that those forests have not recovered.

There’s no forest there. They’ve essentially turned into meadows, with very little tree growth at all — large patch cuts surrounded by high-altitude old-growth forests that, I believe, are self-perpetuating and create their own sustaining environment.

For me, that’s a real-life example of what you’ve been talking about.

When the forest was carelessly removed and drastically disturbed, its ability to regulate the water cycle was lost — and the forest has not returned, even after 65 years.

It’s likely that it would take hundreds, maybe even thousands, of years for that area to become a functioning forest again.

That’s a concrete example of how such drastic disturbance disrupts the entire ecology and all of these interacting processes.

Everything is broken.

And what you’re left with is a self-perpetuating, highly disturbed area — nothing like what was there before the damage was done.

Anastassia:I can testify that there are similar situations — for example, in the Bavarian forests, where there have been large-scale bark beetle disturbances.

Bark beetle outbreaks are related to disruptions of the water cycle, because when trees are weakened by drought, they are less able to protect themselves against beetles.

So first there was logging, then some disruption of the water cycle, then bark beetle outbreaks, which contributed to further forest decline.

Ultimately, in the most fragile areas — such as mountain tops — the forests are now essentially bald.

And recovery is, as you say, very, very slow, if it occurs at all.

These are examples of what Australian researchers have called a landscape trap — a concept developed in studies of ecosystem collapse.

It describes a stable but depauperate state into which an ecosystem falls when disturbance exceeds a certain threshold, below which it would still be capable of self-recovery.

They studied this using the example of mountain ash forests. These forests experience fires from time to time — they are not rainforests where fires are very infrequent.

But when logging occurs, the forests become drier.

Then the next fire destroys even more forest.

Then there may be further logging, and ultimately the forest reaches a state where it is no longer able to recover.

The more we disturb the forest, the drier it becomes.

The drier it becomes, the more susceptible it is to fire.

And ultimately, it is pushed onto a path of complete degradation.

Of course, there are regions where this is less likely because they are geophysically wetter.

But in regions where water is already limiting, forests may function well if undisturbed.

But when we add disturbance pressure, they crash — and their water cycle crashes with them.

This is important to understand because water-cycle regulation is a dynamic process.

The forest “spends” moisture in order to gain moisture.

If one link in this cycle breaks, the whole system breaks.

If the forest transpires but there is no condensation and no precipitation, the moisture is simply lost — and drought follows.

Evolutionary Paradox?

So these processes must occur in the way they have evolved to occur.

If we talk to plant physiologists, they sometimes discuss what they call an evolutionary paradox.

Why did plants evolve to be so “wasteful” with water? They could, in principle, transpire very little.

We know there are plants that transpire relatively small amounts — for example, cacti.

And yet plants, especially trees, transpire abundant amounts of water.

Why such apparent wastefulness? [Is transpiration an “inevitable evil”?]

But it is not wastefulness. It is, as I said, an investment in a more efficient water cycle.

If they did not transpire so much, they would not be able to moisten the atmosphere sufficiently to change its dynamics and to draw more moisture to the regions where they grow.

Recent Research

You were asking about our recent research.

Biotic pump research began by examining precipitation distributions over forests and over non-forested regions — so it was more forest-oriented.

But then we realized that the physical principles behind these moist air circulations are not sufficiently explored.

More recently, we have moved further into physics — for example, studying tropical cyclones and hurricanes.

In tropical cyclones, condensation and precipitation are very well measured.

There are many events, so we have good statistics.

If we are correct about the physical mechanisms underlying biotic pumping in forests, we should be able to quantify the same mechanism — moist air being drawn toward low-pressure zones associated with intense precipitation — in tropical cyclones.

Since tropical cyclones are purely physical phenomena — much simpler than forests or any living system — they are very useful to study in order to persuade scientists and the broader scientific community that these mechanisms are indeed very powerful.

For example, one of our most recent findings — which is very important — concerns cyclone intensification.

When a tropical cyclone intensifies, its wind speed increases and its central pressure drops.

In very strong cyclones, pressure can drop by as much as 100 millibars per day.

We compared precipitation rates in these cyclones with the rate of pressure drop.

Recall that I began by explaining that when precipitation removes moisture from the atmosphere, mass is removed from the atmospheric column, and pressure drops.

What we found is that pressure in these cyclones drops at the maximum rate permitted by precipitation.

It is as if precipitation removes mass and the pressure falls accordingly. Of course, the dynamics are more complex than that — but the rates practically coincide.

This is a new result.

There are thousands of researchers studying tropical cyclones — especially in the United States, where this is a major concern — but no one had examined it from this perspective.

This is very important. It shows that the precipitation mass sink — which also operates in forests — is fundamental to the dynamics of such systems and to the resulting moisture inflow.

So this is very exciting science.

Beyond the feeling that it may contribute to preserving ecosystems — which motivates my research — it is also beautiful and exciting in purely scientific terms.

Concluding Remarks

Glen: We’ve been talking with Anastassia Makarieva. And Anastassia, before we go, I’d like you to tell our listeners how they can find out more about your research.

Can they follow you anyway online? And do you put any of your information out for public consumption, such as on YouTube or Substack or any of those kinds of venues?

Anastassia: Yes, thank you, Glen. I run a Substack called Biotic Regulation and Biotic Pump: How Natural Ecosystems Keep the Earth Habitable.

The address is bioticregulation.substack.com. You’re very welcome to read the materials there — and I also try to answer questions.

Glen: Great. Well, we really appreciate you putting some time from your research to talk with us and give our listeners kind of the intro to this biotic pump concept.

And also really appreciate your concerns about preserving forests and the importance of these old, mature and intact forests that we also share that love here in the United States.

But really want to appreciate you coming on to the show. And we will sign up for your Substack.

Anastassia: Thank you very much. And I want to say that I greatly appreciate the work American scientists have done in this field.

You should especially be proud of the proforestation concept that originated in the United States. I believe this idea should be broadly supported — proforestation meaning allowing forests to develop according to their own ecological laws, so they can reach their maximally competent environmental state, where biotic regulation operates at maximum efficiency.

Unfortunately, we are not progressing very well with this forest preservation. We’re losing every now and then. Not so many victories.

Glen: As one of our heroes said, wilderness needs no defense, just more defenders. And that’s where we’re at. We’re defenders of wilderness and the forests. And I agree.

You know, sometimes it seems like we’re not winning, but we actually feel like we have been making some progress here in Massachusetts.

That’s not the whole United States. Obviously, things are not going well in other areas, but we have been making some progress in Massachusetts here.

Anastassia: I wish you every success. When we were in the U.S. in 2023, we met people involved in forest preservation, so we know you have a vibrant community.

Glen: We do. And we’ll never give up. That’s the key.

Anastassia: Good. Champion this cause, and we will follow!

Don: I just signed up for your Substack, too.

Anastassia: Thank you — I truly appreciate it.

Glen: Thank you so much.

Anastassia: Thank you. Bye-bye.

Glen: Bye.

Don: Well, there it is. That video is a must-see — and we’ve posted the link on the blog.

My Summary

The most difficult part of this interview was explaining why old-growth forests are superior in terms of climate regulation. Given that we know very little about undisturbed ecosystems, this argument necessarily involves an appeal to complexity. (Complexity is central — we even organized a conference on it.)

Environmental regulation is a highly complex process. It involves enormous fluxes of matter and energy, and high rates of information processing — “very,” “high,” and “huge” all in comparison with the capacities of our civilization.

When a process is complex and we do not fully understand how it works, we cannot expect it to continue operating at the same efficiency once we interfere with it (i.e., log the trees). That is the crux of the argument — to which one can add specific mechanisms (such as under-canopy temperature inversion, and many others).

But all this requires a certain basic capacity to comprehend complexity — something that may not be easily cultivated in simplified urban environments.

There is also a vicious circle: being unable to appreciate complexity, we ignore it in wild nature, destroy it, and are left with even less complexity.

It remains an open question whether the same scientific knowledge persuades people equally, given different baseline levels of comfort with complexity. However, likewise, the same emotional appeals can produce even more drastically different responses in people with different backgrounds.

Thus, while I agree with Rob Lewis’ concerns, expressed in his recent thoughtful piece “Are facts enough?”, that relying purely on scientific explanations of why wild nature matters may cause us to sacrifice something internally important, I still believe that rational arguments linking wilderness preservation to human well-being can have broader, more universal appeal.

At the same time, we should use every means available.

Recent Biotic Pump Interviews

2025 The Great Simplification — with Nate Hagens: Why We Need Forests: Their Vital Role in Climate Dynamics, Rain, and The Biotic Pump

2023 The Return of Old Growth Forests, a Ray Asselin film: Biotic Pump explanation

2022 Pascal Cuissot’s film “Rivers Above the Canopy”

2022 Climate Water Project — with Alpha Lo: Biotic Pump

2021 Planet: Critical — with Rachel Donald: Save the Forests to Save the Planet