Science AMA Series: I'm Brian Buma, an Assistant Professor of Ecology at the University of Alaska in Juneau. I maintain and study the longest running series of permanent plots studying vegetation change, succession, and ecosystem response to warming in the world, in Glacier Bay, Alaska. AMA!


I am an ecologist that studies big questions about how landscapes change and what direction they will go in the future. Are our landscapes, forests, and fields resilient to climate? Will they adapt, fail, or be replaced? Fundamentally, how and why do ecosystems grow, change, and end up looking and functioning like they do? Most of the time, that involves fires, hurricanes, landslides, and other catastrophes, or more sedate change as glaciers retreat and life invades.

But there’s one fundamental difficulty all of us scientists grapple with – change takes time. Hundreds of years in many cases. We’ve come up with a variety of ways to work around that problem – looking at young and old landscapes and comparing them, for example (called a chronosequence). But nothing substitutes for seeing things with your own eyes, for actual, observational, ground-level data on how a region actually changes and evolves. It requires just sitting still and watching a system grow, change, and emerge all on its own – long-term research, research which spans multiple generations and lifetimes.

It turns out that the longest running study along those lines – watching an ecosystem grow and emerge from scratch (so to speak) is located in Glacier Bay National Park, in Alaska, USA.

Via funding from the National Geographic Society, I led a group of researchers to rediscover these plots – which turned out to be a bit of an Indiana Jones endeavor. The study was initiated in 1916 by William S. Cooper, one of the founding fathers of the science of ecology in the United States. He went to Glacier Bay and saw a landscape where he could just sit and watch an ecosystem assemble in the wake of warming-induced glacier loss (the warming was from the end of the Little Ice Age). He visited several times until the 1930’s, then his graduate student took over and visited until the 1980’s. It seems simple, but reality is of course much more difficult. Cooper’s directions from 1916 involved orienting by large glacier erratics, visible from shoreline in his day, magnetic compass bearings, distances measured in paces or strides, and crosses painted on rocks. It was a literal treasure map. But shoreline has changed – isostatic rebound from the retreating glaciers has altered sea level and shoreline dramatically. Vegetation has obscured sightlines. Cooper utilized compass bearings – but magnetic north isn’t what it used to be (if you weren’t aware, true north is not your compass magnetic north, and magnetic north changes over time!). Paint has worn off. Soil has built up and buried Cooper’s metal pins. And all of this occurred in the back of Glacier Bay, Alaska, populated by far more bears, wolves, and whales than visitors and where the silence is punctuated by glaciers crashing ice in the fjords.

Through a combination of archival data, old field notebooks, hand-drawn sketch maps from the 1916 trip, photographs from the 20’s and 30’s, modern satellite imagery, and a sturdy but temperamental metal detector, four of us set out to re-find the missing plots via kayaks and foot. After over a week of rain, bear encounters, long kayak traverses, and wandering we were successful. The plots were found, re-igniting what is now a 101-year observational study, the longest of its kind in the world. We now have a precise, high resolution record of vegetation change at multiple locations. These data are being used to test assumptions about our “shortcuts” for monitoring change – like chronosequences. In 2017 we revisited and expanded the plots, bringing them into the 21st century with ongoing work on things like community change, spatial patterning, bacterial and fungal genetics (led by Dr. Sarah Bisbing), and dendrochronology (led by Dr. Greg Wiles).

This work was featured on National Geographic online (, Atlas Obscura (, a variety of newspapers, and featured as the cover story in Ecology (

For more info, check out the website:, with some more pictures here:

More pics and info at my long-term collaborator site Dr. Sarah Bisbing:

…and Dr. Greg Wiles:

I will be answering your questions at 1 PM ET, AMA!

Hello and thank you for doing this AMA.

What are the most impressive changes you've been able to make out? The most surprising?

Is there evidence that these ecosystems are efficiently adaptating themselves, at least partially, to this climate change?


Some of the most impressive changes in Glacier Bay have been geologic - specifically sea level drop due to isostatic rebound. The old directions and pictures show a land dominated by water, with big boats being dwarfed by natural harbors which now aren't much larger than our four kayaks. The ground is bouncing up quite quickly - 5.5 meters so far. It makes navigating around pretty difficult, as all the directions are based on topography that barely exists anymore.

Other impressive changes - that the temporal sequence of ecosystem succession many of us learned in school really isn't working out in these spots. The vegetation present early on really dominates what we see now, and strongly controlled by what showed up early in the 1900's. Flowers, willows, etc? It really does matter.

Why is that impressive? I think about it now all the time, in the alpine or by glaciers which are melting out. As you walk around, you step on plants occasionally of course, and now I wonder if harming that plant, or promoting another somehow (e.g., killing competition) will control what happens 100 years later in that spot. Based on what we're seeing in Glacier Bay research, it could!

So next time you kill a plant establishing in an empty lot, that action could have a legacy that lasts a lot longer than you.

What would you say was the primary lesson you learned from restarting the plots?

What overarching changes stuck out the most to you and your team?

And did you ever use the bear mace?


Bears... yeah, there's a lot of them. We've had a few easy winters, too, so all the browns we saw with cubs had at least two very healthy cubs, usually three. Never had to use the mace. If you make a lot of noise they run off, though obviously you got to be careful near the mamma's. I had to sit in a kayak for quite a while once waiting for a mother and her cubs to clear a beach.

So to your main question - the primary lesson is history matters. None of the plots conformed to what we might expect based on chronosequences done elsewhere in the Bay, or really anywhere - in other words, just saying "well, this place is 130 years old (say), it should be a conifer forest" was completely wrong. So simple expectations of vegetation change over time, that most of us are taught in school, were just incorrect.

The cool thing was instead of just scratching our heads, we have actual, on the ground records of EXACTLY what vegetation was in each place for the last 100 years. So we don't have to make assumptions or guesses - we know that if certain species showed up first, they monopolize resources and "prevent" succession from proceeding (I'm playing pretty loose with terms, but it gets the point across).

In this case, it's willows- if they show up, game over for succession, at least for a century.

The cool thing from that is now, think about the future. Climate change will favor certain species over others, especially in newly available habitat, be it glacial or Arctic. Will they similarly monopolize resources and prevent "normal" ecosystem development? We're already seeing slower than expected treeline advancement, likely due to shrubs preventing tree establishment (, or maybe hares:, exactly what we see in Glacier Bay.

How do compare what happened in the plots to what was expected to happen without climate changes?


Well, in a sense climate change brought us these plots. This part of the world has been warming since the 1800's with the end of the Little Ice Age, which is now being taken over by human induced warming.

In harsh environments, the dominant interaction between species is facilitation - essentially they benefit from being close. It helps ameliorate harsh conditions like wind and cold. In more benign environments, the dominant interaction is competition - we're seeing that become more and more important. So important, in fact, that it appears to be the dominant factor which is keeping these communities stable, despite expectations. Will that continue? All signs so far point to yes.

Has the intrusion of humans into the area had any negative impact on the naturally occurring species thus far? Do you predict that it might in the future?


That's a good question, and something we've thought a lot about.

The Glacier Bay area was actually inhabited for a long time, thousands of years likely - when it may not have been a bay at all, but a river valley. But the local residents, Tlingit groups who now live in Hoonah, were pushed out by the last glacial advance in the 1700's. The retreat of those glaciers left the Bay. Since then, nobody has really lived in there except a few miners, and nowhere near the plots (it's a big, big area).

So the biggest human presence historically has been researchers. We take precautions - we visit the sites in reverse order, furthest from the mouth of the bay first, to avoid bringing seeds from downbay on our clothes. We avoid clothes that collect seed (cuffs, for example).

As for in the future, hopefully not. I do worry about unintentional damage. Even just walking around damages vegetation, because it's so think you can't help but step on willows and alders, and the ground is covered. And our research says even small changes in early communities can alter whole trajectories...

So we take a couple precautions. The sites are outlined with rope to avoid stumbling near them on accident. The sites are not going to be visited each year. The sites are not marked aboveground (you need a metal detector to find the corner markers, which of course requires getting pretty close without a mark).

Most importantly, the GPS coordinates are not public. This isn't to be secretive, but rather to avoid ecotourists. Only a few people a year kayak all the way back there, and the sites are no longer near the shore due to isostatic rebound, but I don't want folks to look for the oldest sites in the world... and step on them.

More broadly, there are invasive species in Glacier Bay. We had a scare this year when we thought we found a Eurasian grass on one site, but it was a local species lookalike, we just needed a microscope to confirm. There are invasives in the park, which is unfortunate:

The location of the plots WAY in the back, far from anybody, is likely keeping them safe so far.

A somewhat personal question: what keeps you up at night?


For a brief period of time, caffeine, but I pushed through it with more coffee.

Seriously though...
1) The further rise of anti-intellectualism in the US and other countries. Really undermines our future.

2) The unknown-unknowns in climate change, mainly associated around tipping points. We know when ecosystems change (often catalyzed by a disturbance like fire or wind, my focal area) they change fast, and it can stick. Tipping points are hard to anticipate. Those in the ocean may be even worse, as it's a bigger, slower system. Heck, it's been a weird weather year in Alaska. Will we know when things really change and simply won't change back?

3) Lately, unwillingness of people to compromise politically. The purpose of a democratic election is not electing someone that perfectly represents your views (unless you're the one running I suppose) but a person that meets the overall needs which almost by definition won't fit anybody perfectly.

4) Human driven extinctions. Certainly species go extinct naturally. But when we do it, it's a failure - morally, ethically, even religiously (most/all religions have stewardship language in them). By almost any philosophical measure, humanistic, naturalistic, religious, or whatever - it's just a failure.

That being said, there's a lot going well in the world too. Life's getting better in a lot of places, science is advancing despite everything, there's lots of great opportunities for students to get involved...

Thanks for doing this AMA!

Have you seen evidence at this site for "phenological reassembly" (changes in the timing of life cycle events in plant/animal species, leading to new combinations of species at different life cycles)? Have these reassembled communities become permanent, or were they just around for a year or two?

Full disclosure: I'm not an ecologist, so I'm not even sure if my question makes sense. But I heard of phenological reassembly when I was tasked with writing a press release about phenological reassembly on Mount Rainier during a warm summer in 2015.

Here's the paper the release was based on:

Thanks for your time!


Good question!

Phenological reassembly is associated with changes in seasonal timing of important community events (e.g. flowering and pollinator communities). We don't have that that temporal resolution - only plant community data every 5 years or so. I can't say, from these data, how fast the phenological events (e.g., flowering) are changing. They certainly are - old notes have flowering happening in August, we see it in July or earlier. But not more more detail than that.

As for the overall community - we are seeing permanent (at least on a century timescale) communities which wouldn't normally be considered permanent in this environment. Unexpected stability in willows, for example, is excluding later successional species pretty effectively - no seedlings, no nothing, of species like spruce despite seed sources.

As for why they are so stable, it's unclear. Certainly they can monopolize resources. And so the legacy of apparently random establishment early on got solidified by competitive exclusion, and remains so, despite expectations of a somewhat orderly progression from herbs/wildflowers - willows - alder - conifer. That's not happening. We know that in more benign environments, competition is most fierce - and this landscape is warming rapidly, and becoming more benign. So it's unclear where it'll go.

There's a lot to read here including the links. What exactly is the point of these spots/plots? Why are they important?


Sure. It's a long story!

The plots are important because they provide an observational record of change over 100 years. Think about how you normally would study a process of change that takes longer than a human lifespan - you would go to young areas, and old areas, and make comparisons. That's a chronosequence (space-for-time substitution). It's often the best we can do. But it's an inferential method, you're inferring that the differences you see are due to time.

These plots don't make that assumption. We see differences, and we know exactly what happened over the last 100 years (101 now!). So when we see very distinct differences between plots, we know it's not time, rather it appears to be who came in first - which we have a photographic and quantified record of.

So, the value of these plots is checking the assumptions of inferential chronosequences, as well as capturing climate change in action. We're already finding that simple assumptions of vegetation and ecosystem development over time don't really work - because our actual record contradicts the inferences made on chronosequences... and in science, empirical data wins over inferences.

For example, we see three distinct trajectories of plants - willows, spruce, and alders. Rather than guessing it's time since plants established, or the substrate, or something like that, we know it's actually due to the random process of seed dispersal in the early 1900's, which led to some plants taking over some areas and some others, and that legacy is still seen 100 years later.

Our climate projections are based on predicting how vegetation will change and expand over the next 100 years - best to get it right, and not make simple assumptions about time -> community!

That's not to say chronosequences are bad, they are just limited. Here, we don't have those limits.

How helpful are the old compasses if the magnetic north is variable?


That's a great question, and was one of the most entertaining aspects of the whole thing. Magnetic north shifts, but not at a consistent rate (it barely moved back then, perhaps why they didn't update their bearings). Thankfully there are reconstructions of where it was historically. So we know that while they didn't use true north in 1916, if they did their declination would be approximately 30 degrees from true north. Ours is 19 now. So you have to adjust their directions by about 11 degrees to the west and it works out - kind of fun, and something I hadn't thought about before.

The real problem was they didn't really say which they were using (magnetic or true) and what their declination was, if they did. Turns out they almost always used magnetic, so it was at least consistent (if off).

What are you seeing in the way of vegetation change? I assume there is a decrease, but could you describe it in your own words?


I wonder why you'd assume a decrease?

We see that the community biodiversity increased rapidly early on - for the first 60 years after glacial recession or so. But after that, it drops. Why is that?

Well, it appears that some species are really, really dominant in this warmer environment. They are able to exclude all other species, essentially halting succession (at least so far). We're seeing replacement of currently dominant species, with little to no indication that the "normal" trajectory towards closed conifer forests will proceed except on those plots where that process started about 60 years ago. So the pattern that was observed in the 1920's is still with us.

It's a cool thing - think about it this way. If you had walked through this environment 100 years ago, and kicked over a few young baby willows, you'd see the legacy of that action on the landscape now - you'd see big alders and conifers. Or if a rock had rolled down the hill and taken out some Dryas (a small flower important to the nitrogen cycle), or if you had picked those Dryas, you'd now see more willow. It's cool to think that such little actions can perpetuate themselves over a century.

what is the smallest shift/change of land/sea features that occurs which has the most impact on the planet's climate, in your opinion?

how significant do you feel that (man-induced) global climate change is, when considering how the temperatures and and conditions of the earth have varied massively over the last few million years? do you believe that the impact of current humans will have long term problems for the planet or is the effect of global warming negligible given earth's history?


Hmm... smallest shift?

The "small" evolution of white rot by fungi was pretty epic, and really comes down to a "simple" genetic shift:

The closing of the Isthmus of Panama was another (I guess large, but small in the big scheme of things). Similar is the closing of the Bering Strait, which influences global ocean circulation and is a pretty big deal.

I think people get a bit mixed up on scales when talking about climate change. For us, on our timescales, it is quite significant. We're talking about humanity, which now is a fairly finely balanced machine of precision but place-based agriculture, people living in places with precarious water supplies, and large amounts of marginal habitat being heavily utilized. Shifts are a big deal, because our systems are built to be efficient, not resilient/adaptable/flexible.

People are adaptable, but that doesn't mean there won't be problems.

Long-term? I would assume the planet will recover, yes, and the species - if we're talking about tens of millions of years. That doesn't mean it's a good thing.

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