Wednesday, July 31, 2013

Fire Ecology: East vs. West

Note: This program first aired on July 20, 2013.

I recently had the good fortune to travel to the Rocky Mountains, specifically the greater Yellowstone ecosystem. For people like many of my friends and me, East coast kids that we are, the mountainous west has long held an almost mythic standing in our minds. Besides the fact that it lacks an ocean, on its face the west seems to have everything an outdoorsy girl could want: bottomless powder skiing, endless trail running, essentially perfect weather all the time, no biting insects, wide open spaces, and more truly high mountains than you could climb in a lifetime. At the end of a solid two weeks of downpours and fog, or when the blizzard ends in rain, sometimes Maine doesn’t quite stack up.

There’s something Maine has though, that the West doesn’t, and it influences the biological community we find here, and minimizes our exposure to one of the more unpredictable, and frankly terrifying natural phenomena out here. I’m referring of course to water, we’ve got it, in spades, and to wild fires, which are pretty rare here in the Pine Tree State, but oh so common out west.

Fire ecology is a complicated topic; it includes factors like climate, weather, forest type and age, tree species, fuel load, and human management. All of these factors can change from year to year, and day to day, and some, like human management decisions, have had repercussions that are felt for decades. So bear with me when I simplify these factors in an attempt to get to some ground truths. Maine is a forested state, and the reason we have so much forest is that we have so much water, specifically, precipitation. Remove human interference and given enough time essentially the entire state would be forested (with a few odd and extremely localized exceptions). The west is different. It gets much less precipitation, and much of what it does get is in the form of snow fall. At certain elevations that is enough precipitation to support forest, but above and below those elevations, temperatures combine with water stress to yield treeless landscapes.

The first lesson you learn in fire fighting school is about the fire triangle, the three components required for a fire to burn. The first is oxygen, chemically a fire is the exothermic reaction that occurs when the carbons and hydrogens that are combined in any kind of carbohydrate molecule recombine with oxygen. No oxygen, no fire. The second leg of the fire triangle is an ignition source. Something has to ignite the fire, lightening and human carelessness are common sparks. The third leg is fuel, which brings us back to our two forests, east and west. Forests anywhere are nothing if not fuel for fires. The frequency and intensity of fires that occur, and they will occur, depends on the volume and flammability of the fuel; just how dry is it? Here in Maine we carry a potentially high fuel load, but it seems our flammability must be fairly low, as the average presettlement rate of fire return was something well over 1000 years. The disturbances to the forests here tend to be small scale (even the fires). The transitional “Acadian” forest that covers much of Maine is not particularly fire adapted as a result, though it is sandwiched between the much more fire adapted boreal forest to the north and oak forests to the south. Western forest and woody shrub communities tend to have much shorter rates of return for fire frequency, a few hundred years for high intensity stand killing fires, and just decades for lower intensity ground fires. The trees in these forests are adapted to high fire frequency, to the point where some of the species are actually dependent on fire at some point in their life cycle. Looking beyond the fact for a moment that as a result of climate change, summers are supposed to get hotter, winters warmer, droughts worse, and precipitation events heavier but less consistent, all of which will potentially lead to more fuel, we have to look at the other way human choices are impacting the effects of wild fires.

It is scarcely two weeks since 19 firefighters were killed in the line of duty in the Yarnell fire north of Phoenix, Arizona. They were working just beyond what is called the Wilderness Urban Interface*, the zone where housing butts up to forest vegetation. This is the big topic of conversation in western fire management circles, as housing development pushes further and further into naturally fire prone dry forest and shrub areas. And it is easy to sit here in Maine and shake our heads at those silly folks building houses in burnable canyons in Colorado and Arizona, but when I look out my window, you know what I see? Trees, and only trees. It turns out that I live in the wilderness urban interface too, though it is a stretch to call West Sedgwick urban. There is actually more housing in the WUI on the East coast than anywhere out west. The problem is that many western ecosystems are so much more fire adapted, they are supposed to burn. And as anyone who has argued with Mother Nature knows, its hard to stop her when she is doing what she is supposed to. So when the humidity is so high it is hard to breath, or the fog so persistent that things start to mildew, or the rain so torrential you can’t see across the yard, I thank my lucky stars I live in Maine, and although I know wild fire could certainly happen here, I don’t have to treat it as inevitable, as I think I would if I were living the western dream, enjoying that fluffy Rocky Mountain snow and hiking all those 14,000 footers. It was fun to visit, but I’ll take our vibrant, almost decadent temperate lushness here anytime.

*The Wilderness Urban Interface is also known by its acronym WUI, pronounced “woo-eee”, but that was just too silly to say on the air.


The Yarnell fire outside Prescott AZ is just one example of the complicated intersection of climate change, human fire management, and unpredictability in nature

Precipitation info for Yellowstone:

A good radio piece on the Wilderness Urban Interface (WUI) from Colorado College:

Sunday, July 14, 2013

Yellowstone Afterglow

Note: This program first aired on July 13, 2013.

Last weekend I was in Montana, for a wedding. We were near Bozeman and the north entrance to Yellowstone National Park, surrounded by high country, open meadows and mountain ranges with names like the Crazies, the Absarocas, the Gallatins, and the Bangtails; a landscape so dissimilar to our home territory of coastal Maine. The air was different, the sun was different, it was a nice change of pace from the fog and damp we left behind.

We had one day after the wedding to explore before flying home, and we chose to make a lightening fast tour of the northern part of Yellowstone National Park, a place I have longed to see but never had visited. I especially wanted to soak in a hotspring; hotsprings being one of the few things Maine lacks that would make it perfect in my mind. Maine formed as the result of plate tectonics and volcanic activity, but the last of this was 200 or more million years ago. Yellowstone, in contrast, is located over a hot spot, a place where the Earth’s crust is particularly thin (3-5 miles in this case). A plume of magma is able to come unusually close to the surface of the Earth as a result, and can influence conditions on the surface. Conditions I was hoping to participate in, like a hot spring. The relatively recent nature of Yellowstone’s volcanic activity (a little over half a million years ago), the size and scope of this activity (described in the literature as “cataclysmic” and “massive”), and the thinness of the crust have ensured the profusion of geothermal features that make Yellowstone unique.

Hot springs result from a special set of circumstances. Water is a requirement, a spring is simply a spot at the surface where water emerges. Proper plumbing is key, the underlying geology must be fissured in such a way that all cracks lead to that one spot where the water is funneled out. Heat is also requisite, and the heat in this case comes from the interior of the Earth, resulting from the radioactive decay of elements like uranium and thorium in the mantle and core, elements trapped there since the earth formed 4.6 billion years ago. Here in Maine our main impediment to having hot springs is the plumbing. We have plenty of water, and there is certainly heat below the crust under our feet. The problem is the crust is too thick, and while it may be cracked, those cracks aren’t connected in such a way as to allow water to sink and get heated and then make it all the way to the surface.

In Yellowstone, precipitation and the melting alpine snow pack drain into the bedrock , which in much of the park is made up of rhyolite, a extrusive volcanic rock that gives us a clue about the nature of Yellowstone’s significant volcanic past. Many minerals are dissolved into this water as it flows deep below the surface, and surprisingly there are bacteria deep in the Earth’s crust that make use of these minerals. The most notable are the anaerobic hydrogen sulfide producing bacteria, which use the sulfur in the water in their metabolism, and produce the smelly hydrogen sulfide gas that is associated with many hot springs.

The spring I went to was called the Boiling River, and while it has a dramatic name, it is a fairly mild mannered thermal feature, by Yellowstone standards. The spring simply emerges out of the ground and forms a short water course before it drains into the Gardiner River. You soak at the narrow interface on the edge of the river where the hot spring water meets the cold river water. You remember the age old question about having your feet in the oven and your head in the ice box? Its kind of like that when you first get in. I would just get in a comfortable spot and the turbulence of the river’s flow would send a burst of cold river water into my lap, like a peal of laughter from the mountains. The characteristic orange mineral build up lined the edge of the spring’s flow, and the rocks were covered with blue green mats of heat loving extremophile bacteria. A perfect last quarter moon hung in a bright blue sky, and we were slightly veiled by the steam that rose around our heads. As I soaked I reveled in this heat that was not from the sun or the woodstove or any other earthly (as we know it) source, but from the deep mystery that is the interior of this rock we ride around the sun. Elements from an exploded star, coalesced into a planet. Elements that are still active, 4.6 billion years later, still releasing energy,  pumping heat into water, water I was sitting in as it emerged from a crack in the ground. I couldn’t stop grinning, even though there were tears in my eyes.

And now I am returned home smelling a bit like sulfur, dreaming of alpine meadows and steaming rivers, and basking in the Montana afterglow.


The National Park Service Yellowstone website:

Nice overview from a Canadian website associated with Banff National Park:

Some nice local knowledge from a park gateway community business owner: *Note: I have never stayed at this place and have no affiliation with the business. This is not any kind of endorsement, I just like the “guidebook” they have on their website.

Sunday, July 7, 2013

Fledging Day

Note: This program first aired on June 29, 2013.

The other morning I got a phone call. It was my niece, saying, “Sarah, Sarah, I found a baby bird on the lawn! I watched it for twenty minutes and it is still there, can I keep it for a day?” I told her to leave it where it was, and that I would be right over. When I arrived we found not one but two baby chipping sparrows, staying quite still in the grass, minding their own business, and two adult chipping sparrows, noisily and nervously flitting about in the trees above. The date was June 14, what many Americans celebrate as Flag Day; for me now it will always be Fledging Day.

Merriam Webster defines fledge, the verb, as “to acquire the feathers necessary for flight or independent activity, also to leave the nest after acquiring such feathers”. The word can also be used as a transitive verb, which simply means it has an object, as in “to rear until ready for flight” or, my favorite, “to cover with or as if with feathers or down”. The definitions make me feel that it is as much about getting the feathers as it is about leaving the nest, which may be, because you can’t leave the nest until you have the feathers.

The little chipping sparrows we found were in fact fledglings, young birds who, under the care of their parents, having grown sufficient feathers, made the leap from the nest into the big world beyond. These sparrows, like most small song birds, are what is called altricial at hatching, meaning they are tiny, without feathers and with eyes closed. They can’t keep themselves warm, and are dependent on their parents for everything. They look like little fetuses, which is essentially what they are. They will live in the nest for days to weeks as they grow, for example, those chipping sparrows were in the nest for about 10 days before they fledged. The rate at which these babies develop is quite amazing, it seems like you could literally watch them grow. For altricial birds, fledging means growing enough feathers to leave the nest, not necessarily having the ability of full flight.

On the other end of the baby bird spectrum (and it is a spectrum) are birds who are precocial at birth, meaning they have feathers, open eyes and are capable of movement when they hatch, and may or may not feed them selves from the start. Ducks and other shore and water birds exemplify this pattern. The babies may not be able to fly immediately, but often they can swim.  For precocial birds, they have fledged when they can actually fly.

It is curious that there is such a difference in the stage of development of baby birds when they are born. This difference is a result of evolution. Nature has presented a problem to birds everywhere, namely “How do we keep our vulnerable young from getting eaten by some hungry predator?” (truly, the problem that faces all parents in the world). For birds, evolution has produced two quite elegant solutions, based on resource availability, and with pros and cons to each. Song birds migrate great distances to come to habitat with sufficient food resources and nesting areas. They have evolved to put their energy into simply getting here and getting down to the business of mating as soon as possible. Energetically that means that they put relatively little into their eggs, and the less you put into an egg, the less you are going to get out of it, hence the helpless altricial young. They are able to invest less bodily energy into egg production because once the young are born, they are able to collect plenty of food to feed them; the parents’ investment is on the outside of the egg shell. This is still a dangerous strategy, though, as finding a nest full of baby birds is like winning the lottery for a predator. It’s a concentrated source of nutrition, those tasty little niblets are all in one handy spot, the nest. Hence the speed with which these babies grow. Evolution has favored the fastest periods of in nest development, because the whole time they are in the nest, those baby birds are easy targets.

Precocial birds eliminate the possibility of having all of the young eaten in one predator attack, by dispersing them from the nest as soon as possible, mainly, as soon as they hatch. Individually they may be picked off, but they won’t all go together in a big gulp. The trade off for this in the physiological preparation of the parents. Their investment, particularly that of the mother, is on the front end of the nesting process; she must eat enough while developing the eggs to create a big fat juicy yolk laden egg. An egg like that contains enough nutrition to grow a baby bird that has feathers and run around as soon as it hatches. This strategy works really well, but obtaining that kind of nutrition on the front end is clearly not an option for many kinds of birds. The process of evolution has guided different bird species in different circumstances in different directions, and hatchling development is a perfect example of this. Happy Fledging Day everyone!


Richard Sibly, et al, Energetics. Lifestyle and reproduction in birds PNAS, April 24, 2012

Mary Holland Naturally Curious 2010, Trafalgar Square Books—This fantastic book is also a popular blog and an email list serve:

Paul Ehrlich et al, The Birder’s Handbook: A field guide to the natural history of north American birds, 1988, Simon and Schuster. A classic, with detailed species accounts and a wide array of content essays.

One of the most comprehensive bird websites out there, from the Ornithology Lab at Cornell University

The information about the evolutionary strategies of precocial vs. altricial young came from the Stanford University bird website: They seem to have an active on campus birding community.