The Pine Forests of Mexico's Trans-volcanic Belt

My first non-aerial experience of the higher elevations of central Mexico was one of surprise.  I did not really know what to expect from the peaks that lay between Mexico City and Cuernavaca, but I figured that even relatively high elevations south of the Tropic of Cancer would be nothing like those further north.  It turns out that the treeline in Central Mexico generally falls at 13,300 to 13,700 feet, which when compared to a much further north Colorado's treeline of 11,500 feet is not really that high.  Mexico City itself rests in a valley surrounded by volcanic ranges that are snow-capped year round, and boasts a really pleasant climate that stays fairly consistent due to its location both in the tropics and at a height of around 7,000-8,000 feet.

The cultivated plant life is not that different from what usually gets planted in the more inland parts of southern California, with Italian Cypresses, Canary Island Date Palms, and even various manzanitas being popular landscaping choices.  Outside of the developed city, however, in some of the last remaining wild land, are expanses of the southernmost sputterings of the Chihuahuan desert which stretches far to the north in Texas and New Mexico, mixed together with remnants of once-extensive wetlands lined with the lovely Montezuma Baldcypress (Taxodium Mucronatum), some of the hardier tropical species that creep in among the lower passes into the central valley, and... pines!  Many pines!  Mexico boasts more native species of pines than any other country in the world, including isolated populations of species that occur far away, like the Eastern White Pine.  Some botanists think that Mexico is the genetic center of pine diversity and the original habitat of the very first pines.

So what does a Mexican pine forest look like?  I suppose it can look like many different pine forests that we have further north, but I was only able to catch some time in the forests of Hartweg's Pine (Pinus Hartwegii), which I encountered about 10,500 feet up in the mountains off of Mexican highway 95.

Source: http://www.geographylists.com/nevado_de_toluca.html, taken by Brandt Maxwell, who has a site that is really worth checking out if you want to see more of this part of Mexico (and many others).  This was actually taken a bit west in the mountains closer to Toluca, but the forest I explored was nearly identical.

As you can see, this forest is a bit more of a closed-canopy savanna, but there are areas that are thick forests of both pines and firs that can put your average stretch of Oregon to shame, with so many different species that identification proved something of a chore.  In addition to this are other shrubs, cacti, and yuccas.  I had initially assumed that heavy grazing was responsible for the meadows, but I saw little in the way of grazing herds anywhere, and did see plenty of healthy saplings in the area.  Fire apparently plays a significant role around here, and it has not been suppressed to the same degree that it is in the United States, apparently because people knew about the benefit it could play for potential grazing.  Regardless of the motives for the slightly open canopy, the same dried up yellow grass we see here continues on past the treeline, which this far south does not always indicate the presence of glaciers and snowfields, but rather that trees cannot necessarily cope with the intensity of solar radiation at this altitude within the tropics.  Then again, I am not really sure, because these forests, like much of Mexico, remain a botanical land of mystery and discovery, at least for me.

The Eastern Forests and Plant Succession

This was going to be another Q and A, but I ran into this question that deserved an extended response:

Q: It really is hard to imagine prairies existing so far east.  Are you sure that some of them are not just abandoned fields?  I mean I know you explained that we once got a lot of fires and such here, but we also have a lot of rain and water in general, and most land that I have seen go to seed again turns into a forest in a bit of time.  I think you just get excited when you find wildflowers.

A: More of a comment than a question.  Maybe both?  Cuomment?  Prairies and more so savannas existed well into areas that we imagine are only forests.  Central Mississippi and Alabama, both notable for being quite humid and rainy places, once had an extensive band of tallgrass prairie known as the Black Belt.  The pine flats stretching from Long Island to Miami were a mosaic of thicker forests merged with savannas, which southward also include wonderful shrubs in the underbrush like the Dwarf Palmetto (Sabal Minor):

Google Earth Streetview at above coordinates, or just south of Vero Beach, Florida, on I-95, east side, northbound.  

All of these areas were much more prone to regular rainfall than the interior plains, but what they shared in common, indeed, what makes grasslands possible is a combination of moisture, fire, soil, and sun exposure.   In earlier posts about how savannas and eastern grasslands work, I noted that the forest and grass were locked into a never-ending natural battle against one another that depended greatly on the specific combinations of the above ingredients.  In places a bit further off of the front lines, the ingredients would favor one over the other.  The suppression of natural fire regimes from the nineteenth century onward have skewed such patterns, but in other ways have showed us accelerated models of what a transition from a seemingly barren prairie into a lush forest can look like, often in a period of a few decades or even less.  While the above picture is somewhat natural and "ordinary", it is also somewhat indicative of what happens when the ingredients have been altered.  The shrubs are starting to take over far more than they otherwise would, and the forest is, well, turning into a forest rather than a savanna or "pine barrens".

Was the above stretch of land ever a thick forest?  It might have been, and it might be again, which is part of the wonderful process known as plant succession that defines the shifting mosaic of landscapes that is natural eastern North America.  Fortunately, there are ways to advance beyond conjecture to figure out what used to be "open" and what used to be "closed", ways which also do a lovely job illustrating what succession is all about.

First of all, we can check records from those who came before us.  When Europeans landed on these shores, they were often amazed at the world that stretched before them, leaving us journals and other accounts of what they found as they pressed into the interior.  While these days we get excited over things like skyscrapers and deluxe shopping malls, people then noticed things like big trees, rocks, and even landscapes that surprised them, like the "park like lands of pleasant Michigan".  We tend to think of our ancestors as hacking their way through a primeval forest that was untouched by the native folk, when the truth of the matter is that they often had a fascinating voyage of discovery and enjoyed the variation in the landscape.

Secondly, we can take a look at what is actually in patches of land like the above shot.  If this was once a "solid forest", there would be a lot of stumps in the palmettos, either from the passing of lumber men or a raging inferno, the latter of which would have taken out much more of the canopy and left us with a different forest from what we see, namely one with either fewer or no trees, or one far more arboreal, as in here:

Streetview, the special friend takes us to I-95 northbound again, this time just south of Jacksonville, Florida.

Where we do have more of a forest, we can also take notice of isolated elements in the canopy.  Where we do have either a really broad tree or one that stands out from the rest of a dominate stand of just a few species, this can indicate that at one point this area did have ground that was exposed.  Why is this?  Well, a canopy, while not exactly perfectly uniform, does more or less expand up and out at a rate that favors quicker growing species which tend to dominate everything else, such as maples.  Very rarely does an opening stay exposed long enough for a massive oak or pine to out-compete a bunch of sun-struck maples.  A really broad oak, for example, might be a sign that the area was once an oak savanna.

Taken in Island Lake State Recreation Area, Michigan.

A lone trooper like this Eastern Red Cedar (Juniperus Virginiana) almost certainly means that instead of growing so well in the shade of the canopy, the tree is a survivor of something far more exposed.

Taken at Brighton State Recreation Area, Michigan.  Yes, I know it looks like an Eastern Hemlock.

In fact, it would not be too out of place to suggest that the above scene may have once looked like this:

At an edge of Island Lake State Recreation Area, Michigan.  

Now I don't know the history of the site pictured well enough to claim it is an actual grassland, either emerging or remnant, but the soil is rather sandy (the hills around there, in fact, are stabilized dunes).  In any case, Eastern Red Cedar is an opportunist that can really only get started and prosper under sunny conditions, and often pioneers tree cover on abandoned fields.  Here it is a passing feature of changing landscape.  In more greatly open areas, such as parts of Oklahoma, it is native but actually considered a noxious weed!  I have seen some on oak savannas, which have always been a bit of a misnomer to me anyway.  Yes, oaks are resistant to fire and can handle the drier conditions offered by exposure, but so can these things, junipers, and pines.  


Regardless of what tree deserves the crown of the landscape, our isolated friends are but another way of showing us that nature is not as compartmentalized as we suspect her to be, but always in motion.  This is how we can get from this: 

Taken at Island Lake State Recreation Area, Michigan.  Prairie Remnant converging into Oak Savanna.

To this: 

Taken at Brighton State Recreation Area, Michigan.  Prairie Remnant with edges dominated by savanna converging into mature Oak-Hickory forest.

To this: 

Taken at Brighton State Recreation Area, Michigan.  A little bit of everything, but mostly becoming a mature Maple-Beech forest, a half mile from the above photo.

Basically, nature provides new conditions that the flora of the area then move in to take advantage of.  At first, sun-loving plants that can tolerate not only a bake but also some rather dry soil dominate the situation.  They can be maintained by fires even if they only occur once every few years to a decade, as competing shrubs and trees will be burned out.  Sometimes, however, the fires will not come around, animals such as deer will not graze on certain patches of ground during years of abundance, and the soil quality might have been good enough to allow some species to make a rebound quicker than others.  Given the chance, many areas of eastern North America will indeed progress from grassland to savanna to a dry forest to a more moist forest.  Again, it all depends on the ingredients available, how they are used, and how much they are used.  


Nature is not static.  Yes, we have prairies so far east of the drier rain shadow of the Rockies not because we share general climate conditions with the plains states, but because nature has provided opportunities for these ecosystems to flourish, but they are hardly always passing elements of the landscape.  This also means that not everything was a forest before we came by and plowed it all into farms and cities.  The forest, as much as the grassland, was dependent on conditions to make it possible in the first place.  Was there a lot of forest?  Yes.  Was there also enough open and park-like land to be noticeable?  Yes.  Very often we do have areas that have been forest for a very long time, often hundreds of years.  Sometimes we even get lucky enough to see a rather lovely marriage of the different worlds.

Taken at Brighton State Recreation Area, Michigan.  In the middle of a mature Oak-Hickory forest we have a shaft of sunlight penetrating to the forest floor and letting a Black-Eyed Susan (Rudbekia Hurta) grow amidst its much taller friends.

When the Beach Seems Like a Good Idea...

...everyone else will be there too.  Much of the continent is baking today, with even some of the Cree towns around James and Hudson Bay reporting in 80+ degree weather.  Some areas in Kansas and Oklahoma are calling in 108 degrees, which is actually the same temperature that Death Valley is reporting!  The map below illustrates how hot we are getting, and it also shows where some of the natural features of the continent (well, the United States anyway) are fighting back against the sweltering mess.

As we can see, the mountain ranges are somewhat effective at walling off the heat, or at least keeping it off of themselves.  The Great Lakes are dulling the northward push a little bit, at least by a few degrees, and much further where the deep cool waters of Traverse Bay are knocking things down into the seventies.  Florida is not suffering too much either, as the hot and humid waters surrounding it seem to be effective enough in holding off both the extremes of hot and cold alike.  The northwestern states, as usual, are blessed by being blocked in both by highly prominent mountain ranges and a cold northern Pacific Ocean which carries the California Current past its shores, which also benefits immediate coastal areas as far south as Tijuana.

That in mind, I would love to be here right now:

That would be South Laguna Beach, where the sea is a cool 65 degrees and the air is holding at about 72, and yet sunshine and palm trees still hold dominion.  Like I said, though, most of the Los Angeles metro area is probably thinking the same thing.  Southern California, at least on the coast, is a dream destination for those seeking summer moderation.  The beaches are wonderful, usually completely natural, and have fun things like the tide pools and sea caves that protrude from the land at the top of the picture.

In case you were wondering, those are Mexican Fan Palms (Washingtonia Robusta) towering over the parking lot, and yes, they are exotic to the area, but not entirely alien, as they naturally grow within a couple of hundred miles to the south of here in canyons of Baja California.  The municipal authorities in the region have plans to not replant these things (which have naturalized anyway) in order to create more a more native, shady landscaping "theme".  While I do think this is mostly a good idea, the palms take up so little space and use relatively little water.  They handle the salt spray pretty well, and let's face it, a palm tree on a beach or in the region's lovely sunsets is just a pleasant thing.

Anyway, find some friends, form up a car pool ride or take some mass transit, and hit the beach or some place close to a large body of water or a higher elevation and have a new appreciation for such places.

Wednesday Filler: Blooming Cactus Season in Michigan

Yes, Michigan, Ontario, Minnesota, and even Alberta and other chilly places have blooming cacti, many of them often decently large in size and comparable in beauty to the finest specimens from the deserts.  Here we have a picture sent to me from a fellow invasive species combatant, taken at Grand Mere State Park on Lake Michigan in Michigan, not far from the Indiana border.

Courtesy of Brad Anderson

This would be an Eastern Prickly Pear (Opuntia Humifusa).  While this particular patch does grow on a stabilized sand dune, the environment surrounding it is far from an arid desert.  All it takes to establish one of these things is some well-drained, usually dry ground with a good amount of sun baking it, which usually means they are somewhat exposed.  Even when in bloom, a prickly pear is often missed by people focused on their horizontal field of vision.  After all, there is a stunning lake view and a lovely forest in view at chest height, whereas down there is mostly grass, pine needles, dead leaves, and little wonders like this, a botanical chain link between the western and eastern lands of the continent.  One wonders what the early settlers and explorers would have made of such a sight.  They probably either ignored it or figured they were on the verge of a desert or some place much warmer than what they had been told.  

North America's Artificial Tropical Land: Southern Florida

With the exception of historical photos, data maps, and otherwise very impressive photographs and videos, I have wanted to display only pictures that I have taken.  This is not so that I may show off my amateur photographic skills, which a professional photographer friend have said are lacking, but so that I may present things from experience and a personal perspective.  Pictures are wonderful things, but as I have stressed so many times before, they don't complete the story.  That said, I have not been to certain parts of the continent in a while, meaning I don't have a lot of pictures around.  At the same time, even a picture backing up descriptions of sensible experiences is still just a description.  Let's face it, the time has come to move around a bit a more here, and so from here on out, I will be making use of images gathered from around the internet (so long as I have some sort of a sensible connection to them).  When they are not my own photographs, I will include their source in every caption.  This will also be a great way to explore "off the beaten path" from more than just the blog.

So, that in mind, let's head to the Florida that exists beyond the tourist hot spots and postcard perfect beaches.  Why?  Because when I was browsing some nature books last night, time and again, I came across a refusal to document anything from southern Florida (and Mexico) because it feels too much like a copy of the Caribbean islands.  If you ask me, I think they were just afraid of the production costs of adding in a bunch of more pages to make their guides exhaustive, but here we are.  Southern Florida is a very unique place on this globe, deserving of far more recognition than to be dismissed as "part of something else".  True, it does have some botanical and animal species that are also found in Cuba, the Bahamas, and southwards, and it also has some species that extend their range slightly into the tropical realm from as far north as Quebec, like the Red Maple (Acer Rubrum).  Raccoons (Procyon Lotor) live alongside American Flamingos (Phoenicopterus Ruber).  More unique and becoming increasingly rare is this scene below:

http://forums.gardenweb.com/forums/load/palms/msg0319222516174.html?28

Here we have a wild Florida Royal Palm (Roystonea Regia) growing in a hammock among the Bald Cypress trees, which are noticeably bald during the winter, even though it is commonly in the mid seventies or warmer even in the depth of January.  Deciduous trees do still lose their leaves here, though sometimes the change of brilliant color to bare branches back to spring flowers and leaves only takes a matter of weeks, if even that long.  For the most part, the casual visitor to southern Florida will not even notice this subtle transformation of a pretend winter, as the wild areas that do remain are full of enough broad-leaved evergreens and pines that the northern species do not make much of an impression.  There are native mahogany trees here, as well as the Gumbo-Limbo (Bursera Simaruba), three kinds of mangroves, and 13 native species of palms!

The parts that are not wild, well, they are packed so full of exotics and invasives from the tropics around the world that one would be hard pressed to find something genuinely southern Florida.  This happens to be the case because it is the one place in the United States where tropicals can safely be grown, and in the fine American tradition of planting one's property with perceived beauty over native species, there are manicured lawns everywhere along the suburban streets of Miami and Fort Lauderdale that boast just about every kind of flowering tree and palm you can imagine.   I would know, because when I was growing up, it was the first place and time where I realized that many of the trees around me were not there when things were wild and untamed.  I was six years old and had just taken an interest in both reading in English and noticing that the trees in our Fort Lauderdale backyard were very different from the trees in our Milton, Ontario backyard.  Of course, at that time, even while I wondered what "forest Florida" looked like as opposed to city Florida, I also delighted in the sheer beauty of all the tropical flowers, trees, and even lizards around me, native or not.  I did not care that everything was here artificially and introduced, and especially did not mind that we were even in the actual tropics.


That's right!  Southern Florida does indeed have a tropical climate, but even Key West lies 40 miles north of the Tropic of Cancer.  This is because the land is surrounded by water, and very warm water at that.  This is the birthplace of the Gulf Stream, which also (usually) makes Europe's winters much warmer despite being as far north as much of Canada.  Artificial climates and plants aside though, nothing can really take away from how exotic this land is, both its manicured Miami environs and its primordial but vanishing Everglades wilderness.  The contrast is very noticeable:

Much of the densely, yet comfortably, packed urban areas are built on the only true solid ground in the land, a ridge of limestone which rises only 10 feet or so above the surrounding ocean and everglades, with 24 feet marking the highest point in Coconut Grove, a Miami neighborhood which has retained much of its hammock character of dense mahogany and Gumbo Limbo groves towered over by pines, palms, and the odd high-ground Bald Cypress.  Still, Coconut Grove is but a remnant, and a very incomplete remnant, of what the Miami rocklands once looked like, which was mostly dominated by southern pines.  Development aside, the absence of regular fires in the landscape has altered what remains of the vanished pine rocklands even more. Below is a sample video of some of what remains of this ecosystem and the role of fire in maintaining it, presented by Everglades National Park, which gives you a pretty good idea of what Miami looked like before it was Miami:




This is also a good video for illustrating the role of fires even in a wet and humid place like this.


Outside of the developed areas are vast open prairie-like stretches of sawgrass interspersed with other hammocks; in essence, a very wide, very slow river that drains much of what is green on the map there.  Much more can be said about this unique extra-tropical tropical land, but hopefully this post has served as a nice introduction to one of the extremities of the continent, which we will be revisiting a lot in the future.

On the Concept of Native Gardening, Part Three.

Part One.

Part Two.

In the years following the Spanish conquests and explorations of the sixteenth century, entire populations of Native Americans started dropping dead.  The Spanish had brought (inadvertently) a host of diseases with them which the isolated populations of the Americas had thus far managed to avoid.  While Europeans, Asians, and Africans had managed to build up immunity to certain diseases, maladies like smallpox now had the chance to affect a vulnerable population in the New World.  Along with their diseases, the newcomers also brought plants and animals that would find an open market to thrive and threaten to overtake their native counterparts, a tragedy which continues to this day.

So? Who cares?  Nature can't take care of itself?  Well it can, and sometimes nature can respond rather rapidly to sudden introductions between environments, but in many cases, we are a force of change that outpaces natural evolutionary process.  Sure, nature can be catastrophically destructive on its own, too, so we should not get upset when a hurricane or tornado wipes out homes and such, right?  You see the point...

So how bad are invasive plants?  Unlike the exotics that will rarely reproduce or do so at the same pace and type of spread of other plants, invasives are species that can do any or all of the following, in the absence of their native biological controls:

1. They grow much faster in their new home to the point at which they simply outgrow other things.

2. They can thus also crowd out other vegetation, meaning that if other things would start to grow along with them, they would be denied sunlight and nutrients, or even just sheer space, by the invader.

3. In doing this, and even when native plants do hold their own in competition, the invaders take away from the available food sources for animals.

4. They release either salts or chemicals into the soil to actually prevent anything from becoming competition again.

And then also, dependent on us yet again,

5. We still find such invaders beautiful and tasty and actually remove natural vegetation in favor of the invaders.

Now, this does far more than just outrage native purists like myself who like to see the landscape as it was designed by the Creator (yes, yes, I know, a loaded statement on all sides of the debate of Darwin vs. everyone else).  While I would like to illustrate the heinous nature of Kudzu (Pueraria Montana, and don't ask me how an Asian plant got a Latin name like that), it appears that I missed out on some photo ops of the deadly vine.  You can read more about it, and find some amazing pictures, here:

http://www.jjanthony.com/kudzu/houses.html

Instead, we can take a look at the forests and wooded places of Michigan yet again and stare sylvan death in the face.  I speak, of course, of Garlic Mustard (Alliaria Petiolata).  Garlic Mustard bears all five of the above marks of destruction.  Here we have two pictures of our "friend", the first for an example of how densely packed it can grow, the second for an example of what it can do to a forest.

Now, if the second image did not look at all that terrifying, keep in mind that that spread of the stuff goes well back into the underbrush.  It crowds out everything else, even itself, and when it dies it releases over a thousand seeds that explode into a decent cover of the area around each plant.  As if this were not enough, it releases allelopathic chemicals into the soil which its roots grow in.  If for some reason the plant would not reseed and germinate successfully, it would prevent anything else from doing that either.  It spreads like crazy, enough so that eradicators such as myself have been completely demoralized by seeing it everywhere. (And yes, this is what I do with my days, tromp through the forest, swamps, and prairies looking for stuff like this and removing it).

What happens when hopeless cases like me don't get out there and tell it to die and never come back?  You see that lovely forest up there?  That would become a memory.  Sure, it will not kill the trees outright, but eventually, they will fall or die by some other means and not produce future generations...  This thing literally not only harms biodiversity, it outright eradicates it.  In its native lands of Eastern Europe there are things that eat it and plants that have some degree of defense to its chemical warfare.  Here, even a starving deer will not even touch it, and our normally robust native plants get all wimpy around it.    Perhaps in time plants would adapt to this pest, but by then our natural lands would look very, very different and be quite dead... So how did it get here?  People thought it was tasty.  It tastes like garlic, well... bland garlic.  A bag full of the stuff smells like someone torched an Olive Garden, meaning it can make even a garlic lover like myself want to turn my nose.  Some people even think it is pretty and consider it a wildflower, which they either try to replant or let wreak havoc on the margins of their gardens and properties.  In this case, the choice to not garden with natives actually destroys the local ecosystem rather than simply result in an "also ran" landscape. 

Perhaps this would not be so bad if it were only Garlic Mustard engaging in ecological war crimes, but the truth of the matter is that we have a lot of invaders out there.

http://plants.usda.gov/java/noxComposite

Now don't get me wrong, this happens elsewhere in the world too.  We send stuff to Europe that has already had fun in destroying what little virgin landscape they have left there.  Invaders are just bad news everywhere.   Before you plant or before you decide not to weed, look up what you are introducing/neglecting.  Likewise, when traveling, be aware that not everything you see might belong there, which can sometimes kill the mood when you are impressed by the local flora, but can also help one appreciate what does belong there even more.  We are blessed in that for the most part, our continent still has a fair portion of its natural appearance intact where the lands remain undeveloped or have reverted to the wild.

Sunday Afternoon Post: Where the Plains Rise

After a sweaty afternoon of tromping through a tamarack fen to eradicate Glossy Buckthorn (Frangula Alnus), a venture in which I got stuck in the fen muck quite a few times and got swarmed by every kind of insect ever, well... my thoughts turn to someplace much drier and muckless.

7 miles east of Longmont, Colorado.

This would be along US 36 Northbound at, as the title suggests, the diminutive birth of the Rockies as the Plains rise up into something resembling stubby mountains.  It's a pretty dry place, with only some junipers managing to take a lease on life and then only on the places where the slope and a slight rise in elevation both captures more moisture than normal and change the wildfire regime.  The grass cover is deceptive; there are a ton of yuccas, small cacti, and even sagebrush growing in there.

On the Concept of Native Gardening, Part Two.

Part one can be found here.

In the last post of this series, we explored the wonderful world of native elements in a garden and yard.  Now we move on to things that we have introduced to this continent, which are otherwise known as exotic plants.  For today, we can stick to the relatively good stuff, and just leave it at exotic and not invasive, which we can take a look at Monday.

Exotic Plants.


The word can be deceptive.  While exotic can indeed refer to something really beautiful and stunning, it mostly just refers to things which are foreign to the native habitat in which they are now cultivated.  In many parts of North America, especially in urban and suburban areas, exotic plants account for at least a third of what you see, including invasives.  Many of the more functional plants, namely trees used for shelter, shade, and windbreaks, lawn grasses, and some crops have been imported from Europe.  What can we say?  We like bread made from wheat and beer made from hops and barley.  We like our wine to be made from various strains of Vitis Vinifera rather than the more robust tasting North American natives.  We absolutely adore orderly rows of Lombardy Poplars (Populus Nigra) when lining our city streets and making windbreaks on farm fields.  We are not entirely Euro-centric, however.  Your average flower bed and garden will have Asiatic hollyhocks and hydrangeas growing well, and in the warmer parts of the continent African and Australian plants are all the rage.

For that matter, exotics do not even need to be from another continent.  We have an overabundance of Colorado Blue Spruce (Picea Pungens) in the eastern United States and Canada.

These are exotic, having been introduced from the other side of the Great Plains.  Likewise, Floridians are fond of the towering Mexican Fan-Palms (Washingtonia Robusta), and California and northwestern Mexico accept Southern Magnolias (Magnolia Grandiflora) in return, which are also planted northwards as far as the climate can support them when cultivated with care.  The point is that, like much of the rest of the world, North America has a ton of foreign elements in our botanical ensemble.

Now, are these bad?  No, at least as long as we maintain some wilderness and wild spaces, parklands, and make sure that our native ecosystems are not threatened by new species.  Why are they good?  Well, you try eating a baguette made out of corn.  A corn tortilla is amazing.  A corn baguette is a mistake.  Our gardens have been greatly enhanced by combining elements of flora from around the world, and I personally cannot live without a bed of snapdragons planted every year.  I am exceedingly fond of my Bald Cypress growing 300 miles north of its natural range, so much so that I record minute details of its growth every day.  (What?  We all have quirks.)  Don't get me wrong, native plants are lovely and impressive, but variety can be the spice of life, and zone and climate denial is a very fun aspect of gardening.  Not only is variety fun, it is also a wonderful reminder of how we have coped with our environment from the time we first learned to stick something in the ground and make it grow a certain way.  We have developed so many cultivars of flowers, fruits, vegetables, grains, and even trees in a relatively short length of evolutionary timescales.  Exotic plants are essentially an extension of our interaction with the natural world into that same world, a real miracle in and of itself.  While we can decry pollution and resource mis-management, we can applaud leaps in efficiency regarding agriculture and sustainable forestry.  In North America, we have managed to do this really well:



At the same time, on this same continent, we can also see how much we have changed in the past few hundred years.  People who don't think much about the abundance of Blue Spruces probably figure them to have always been there (some even think they grow in straight rows naturally).  People might figure that Los Angeles might not have always had skyscrapers and freeways, but they also might assume there were always a variety of palm trees growing in pre-colonial California (they were not).  Southern Florida has been changed beyond recognition, even in parts of protected areas.  Sometimes the ignorance has extended into professional forestry, with exotic trees being planted instead of the natives that belong and can flourish better there.  While invasives can thrive because of ignorance, non-invasive exotics can sometimes grow nicely but fail to reproduce.  Worse yet, the plants themselves, while remaining benign and non-intrusive, can still host certain insects and pestilences that can devastate our natural flora.  The disappearance of the stately and formerly widespread American Elm (Ulmus Americana) is but one very sad example of what happens when disease travels with garden imports.  We can end up losing our natural heritage at worst, and diminish an appreciation of our natural ecosystems at best.  The most helpful thing to do is to remind ourselves that an exotic is exotic.  It was put there by us, sometimes only survives because of us, and can compete with or make us forget about what was there before us, which happens to be remarkably good at surviving without us (which is a very helpful thing economically, no?).

Exotics are not evil, and by no means do we need to get on an aggressive campaign to eradicate them.  Invasive exotics, on the other hand...

A Semi-Retraction

About a month ago I posted about how lovely prairies can be by posting this.  I was a bit tired and had a headache or some excuse, because this is actually an invasive plant, Dame's Rocket (Hesperis Matronalis). It is pretty, but not naturally representative of what our grasslands used to/can look like on their own accord.  Granted, some fields of lupines and other native flowers can put this to shame!  Dame's Rocket was one of the first invasive plants to find its way to our shores, back in the 1600's.  While not particularly dangerous, it can crowd out native vegetation and cause car accidents because it is so pretty.

Q and A Session Five

Q: You seem to jump around not only the geography quite a bit, but also from nature to civilization and history, etc.  I thought all this was supposed to be seeing North America for what it really is?

A: What North America "really is" is a continent that has been dramatically transformed in only a few centuries, much of it far more rapidly than that.  American Voyages is all about showing people what they have in their backyard, because it is amazing how many people really do not know what is just around the corner from them, what has happened there, etc., to say nothing of what lies further afield, especially in one of the neighboring countries.  Part of sharing what places are like involves:

What was this like in its natural state?
What has happened here because of nature?
What has happened here because of people?
What is this place like now?


I like to focus on the first and the last question, but you really can't get from one to the other without the middle two being asked as well.  Question one holds a particularly strong interest for me, because in so many places we just have no idea what we have changed, and might never get the chance.  Understanding this, especially through the lens of history, is very important in getting to know ourselves better.  For that matter, it helps to ground the sciences, such as botany, in something not distanced from humans.  Simply put, we are a component of the environment, and a danger lies in ignoring this by either insisting on our dominance of creation or seeing us only as an invasive element within it.  Anyway, whenever studying anything, it is important never to do so entirely from within or without a fishbowl.  This, of course, leads to another question:

What is my perspective on these things?


I made this blog because I wanted to share my perspective with others so that I may be in turn enlightened by theirs and open our worlds a bit more.  I suppose I could say the idea for American Voyages came when I was in high school and shocked that some of my peers did not know much about the world beyond their county.  I became aware of the idea when I went to Mexico to learn Spanish and was exposed to a much broader viewpoint of the place than I expected.  Finally, as noted before, in my very second post in fact, I became enraptured by the sheer grandeur of the Grand Canyon and knew that I wanted to share not just impressions of my travels and research, but my wonder.  Many people could care less about the facts and would prefer to skip ahead to "what is it like?"  To answer your question, in considering all of the components of a place, meaning its ecosystem, history, and forces of change, I like to expose both the facts and "what it is like".

Q: Why so much attention on a few places?  Why all the focus on Michigan?

A: I live here, and I have taken a lot of pictures of places like here and southern California.  I like to present posts that include photographs whenever possible, and I like to make sure they were pictures I or someone I was with have taken just to keep the images pertinent and meaningful in sharing my perspective.  Anyway, what's the big deal with Michigan?  It tends to not get a lot of good press from the rest of the country, to say nothing about getting much press at all.  On that note, just wait until I get some Mexico pictures together, because then you will probably be sick of those too!  Don't worry, I have plenty of requests and plans for more variety.

Q: What is corn?

A: A grain often eaten as a vegetable that is native to Mexico and has been cultivated throughout the Americas throughout human existence here.  In English it can also refer to grains for making bread in general.

On the Concept of Native Gardening, Part One.

One of the great ways to experience some of what one's own backyard has to offer is to brighten up said backyard with some local flora.  This is known in landscaping and gardening circles as working with natives, that is to say flowers, herbaceous plants, shrubs, trees, cacti, and even grasses which are indigenous to the local area.  Ever since I made American Voyages, I wanted to post about the joys and benefits of native gardening, but as I survey my own domain, I find that I happen to like not-so-local things in the yard as much as the next person.  Instead of trying to create an oak-savanna or a beech-maple forest (both are found in remnants within the same few square miles around here), the latter of which might be frowned upon in our suburban fantasy world of golf-course trim lawns, I have some roses, azaleas, morning-glories, and heck, even a Bald Cypress growing.  Last night I even found a hardy cultivar of the lovely evergreen Southern Magnolia (Magnolia Grandiflora) for sale, adapted for outdoor planting in lower Michigan.  At this point, staring at the native elements in the lawn, a slight grimace came over my face as they reminded me how they were surrounded by exotics, and I realized my eco-hypocrisy.  

My horticultural sins put to light then, what types of things can we plant, what do they qualify as, and what are their benefits and/or drawbacks?

Native Plants.

Native plants, as noted, are things that are indigenous to the local ecosystem.  The term indigenous can be difficult to define, especially when we consider time parameters as one criterion.  Something that seems to belong to a place these days might have only found their way there within a few thousand years or so, true.  The global climate does change without human assistance over gradual periods of time, barring a natural disaster of planetary scale (such as a big old space rock hitting us).  Technically speaking, under a vast scale, things like moose and humans are not indigenous to North America because they migrated here over the Bering Land Bridge during the last ice age.  That said, we can pretty much claim that both Bullwinkle and our native peoples are, well, native, as both person and moose naturally found their way here, the moose no doubt being chased by a band of hunters across the dry Bering, neither knowing what they were getting into.  Examples of native plants would be Live Oaks (Quercus Virginiana) in Florida or Black Spruce (Picea Mariana) in Ontario.  Having a native plant in your landscape and garden is almost always a good thing, though this depends on the condition in which the plant is expected to grow.  While a fern might be native to one's area, planting it in full sun requires it to get watered really frequently, which is an inefficient use of water.  This said, here we have two sub-categories of native plants:

Native Plants in and out of Habitat.  

The fern example stands out well, but flowers work even better.  In the yard I have a single Purple Coneflower (Echinacea Purpurea, which has to be one of the most poetic scientific names out there), which is indeed native to Michigan and can be found in savannas and prairies in the state.  Right beside it I have a Wild Columbine (Aquilegia Canadensis), which is native to Michigan and grows on the margins of forests and along similar clearings like river banks (and is also the flower on the blog header).  In the foreground is a sprouting Rough Blazing-Star (Liatris Aspera), native to Michigan, and another prairie and savanna species.  They are all planted beneath a charming Northern Pin Oak (trunk pictured, Quercus Ellipsoidalis), which just so happens to have an isolated native population here in Livingston and neighboring counties.  

Yes, I plant flowers directly into the lawn.

Now the coneflower is not extremely out of place here (though it does not have a record of being native to this exact county, but does right next door, which I dispute, which means I need to hunt some down).  The field across from the subdivision actually is reverting to type into a savanna, and remnants can be found across the main roads adjacent to this field.  The columbine is sort of out place, but as the savanna is surrounded by forests, not terribly so either.  The blazing star is about at home as the coneflower, perhaps more so because they definitely occur in the area, and less so because they like a little bit moister of a setting than the local prairie/savanna.  The oak, though planted by developers solely as a pretty landscape thing, is right at home.  All of these being together naturally, however, is improbable.  Sure, the yard could have once been one of the edges of the savanna grading into the forest and a columbine could be next to a coneflower as such, but... well in any event I suppose this is being overly technical.  The point is, some of these are slightly out of habitat, and some might be in habitat, minus being grown in a lawn of non-native grass.  

How is this good?   Well, I have planted things that belong here, more or less.  Insects get a chance to pollinate something that would otherwise not exist in a developed area, and a semblance of the native ecosystem is restored, albeit by introduction, native but introduced.  The butterflies in the yard are plentiful and the whole scene is thus rather idyllic.  How is this bad?  Well, it happens to be a bit fake, but nature will not complain even if a botanical purist might.  On that note, it would be a bit improper if this were not a lawn  but a prairie remnant trying to be rejuvenated.  In any case, this is the best I can do at making a nice little reminder of what was here without getting a citation for growing a prairie instead of a lawn, which in my opinion is sad, but people like their lawns.  

Anyway, in the same vein, another good example of an introduced native, the Eastern Redbud (Cercis Canadensis).  I apologize for the poor lighting quality of the image, but I only recently learned about the magic of light control on cameras.  

Taken at St. John's golf course in Plymouth, MI.

Redbuds are indeed native to southern Michigan and are often a very striking part of our moister forests.  They are so lovely that they tend to get planted a whole heck of a lot.  They serve as an excellent example of "good plants" we see in our landscapes that would not have been here without human intervention, at least not in quantity, but are not entirely foreign elements of the local area, just the particular ecosystem in which they have been introduced.  This means they might not have popped up here by themselves, but they also blend rather well with the local environment.  Many plants reproduce by seed, and often the seed is carried to new places by animals, animals which sometimes also create new ideal conditions for the plant to flourish (browsing, den and nest creation, etc.).  You know what?  A guy finding a nice iris in a nearby marsh then planting it in his garden is sort of doing the same thing, albeit for aesthetics rather than as a matter of survival.  

So why all the fuss about what belongs and what does not?  Find out in two days and four days for parts two and three of this rant, as well as tomorrow when I do a little Q and A.

Wednesday Filler: Happy Summer Solstice

The days have been getting longer up until now, when they will sadly, slowly, start getting shorter again.  Enjoy the long day!

I-70 Westbound somewhere within 20 miles of this Kansas-Colorado state line, in Colorado.  The sun is setting to the North on last year's solstice.

What is Going on With Wildfires? What is Going on With the Blog?

In the last few months abnormally hot and dry spring weather has given life to an extended wildfire season.  To date, we have seen massive fires in New Jersey, Michigan, California, Colorado, Wyoming, New Mexico, and other areas.  The conservationists tend to point the blame on human-induced climate change, while the developers claim that such fires are the result of over-zealous preservationist schemes which have given us overgrown landscapes and the turning of a blind eye towards residents of such regions.  What is true?  Who is to be believed?  Well, it depends on the situation really.  Take our fires in the Rockies around the Front Range and the Medicine Bow Mountains.  A likely cause of such wild spreading flames would be the vast amounts of fuel that are available to the inferno, but not because of any overgrowth.  The fuel here is dead trees, mostly killed off by the Mountain Pine Beetle (Dendroctonus Ponderosae), and his colleague, the Western Spruce Budworm (Choristoneura Occidentalis).  Both insects are opportunists, going mostly after old, decaying trees, and the younger trees which have yet to develop adequate defenses against their attackers.

This tends to fulfill a nice role in the natural cycle, but only when nature herself is experiencing a proper cycle.  In the past few decades, temperatures have been rising in the region, and a life cycle that was largely restricted to an adult stage in the brief alpine summer of late June through August has now moved up as much as a month or more.  Simply put, the bugs are looking for more to eat, and they are also getting higher up on the slopes that would have been too cold for them to handle.  What gets left behind?

Dead forests that just explode when a fire happens to come into the area.  There have been a lot of big changes to the Rocky Mountain ecosystems lately, and with the High Park Fire being news lately, this has raised a lot of big questions yet again in the political arena.

I had posted on this earlier, in a post on the source of the Colorado River.  I used cautious language then, as I often do in this blog, because I want people from a wide variety of political viewpoints to read what I have to say and discover the raw beauty of our landscape without turning away because of some fear of a radical conservationist viewpoint.  While I do not retract my statement made in that post about the insect issues in Colorado and elsewhere, I will say that what has turned our forests dead has probably been the insects.  You see, this is what is so tricky about this and so many other issues regarding the natural world.  Environmental issues are heavily politicized and the preservationist instinct is so strong that some times conservation efforts also turn into a semi-religion while the opposition points this out and tries to gain the upper hand by decrying such sentimentality.   One of the "religious" issues, of course, is wildfire.

For most people, an image of a forest fire would probably be a bad thing.  Most of us from North America are familiar with Disney films, among them the famous Bambi which featured a scene involving scared animals running from a huge forest fire towards the end of the movie.  I know it scared me to death when I saw it as a child, especially since I was familiar with the lovely forests of northern Ontario in which I grew up.  This and other images in popular culture have stuck with us, and the idea that forest fires are bad have been seared into our consciousness ever since.  Frightening and tragic news images of homes being destroyed have only added to a public fear and distaste of wildfire.  We get upset when a church burns down, and sometimes even more so when the cathedral of nature is torched.  Surely, then, wildfire is an evil to be expunged!  Not quite, but nor is it to be actively embraced.

This sort of thing got wild land management into big trouble throughout North America when it turned out that protection efforts and suppression of fires, regardless of whether they were naturally occurring or set by humans, were actually detrimental to the natural cycle of many ecosystems.  Fire, you see, is an agent of change, often a very good one.  Our grasslands, in fact, depend on it, to the point where our native peoples actually set fire to prairies in order to clear out dead grasses and rejuvenate the soil.  Oak savannas, the southeastern pine barrens, and other park-like openings in the wetter east actually existed both because of soil conditions and because of fires that kept the landscape from turning into a forest.  The Jack Pines (Pinus Banksiana) of the Boreal forests can actually reproduce only when fire opens their cones, and the towering Eastern White Pines (Pinus Strobus) formed a supercanopy over a dense lower canopy of beech-maple forests throughout the Great Lakes and St. Lawrence Valley because that lower canopy would sometimes open and fire would take care of competing trees.

As noted, native peoples would sometimes do burns of their own to create better hunting grounds or farming conditions, but by large nature was in control of the landscape.  Fires would often be caused by lightning, sometimes indirectly by smoldering within a great tree.  Dry fuel like grasses would often easily catch fire, while in other places towering pines in the supercanopy would be an easy target for the wrath of a storm.  This is where speculation and modern observations made during abnormal conditions can often take us for a ride however.  In some cases, we might even tend to think that fire happened so often that without it, nature can't cope!  Fortunately, people with some amount of an appreciation for a broader picture work at the United States Forest Service, and have left us with a map that theorizes what natural fire regimes should look like:

Courtesy United States Forest Service: Brown, James K.; Smith, Jane Kapler (2000). "Wildland fire in ecosystems: effects of fire on flora". Gen. Tech. Rep. RMRS-GTR-42-vol. 2 40,56-68. 

I would absolutely love a map like this for Canada and Mexico, but I take what I can get...

Looking at the light creams and yellows of the grasslands and the blues of the eastern tallgrass prairies, savannas, and forests, we see that fire could have indeed been a frequent part of the natural cycle, perhaps to the extent that annual fires were not entirely unexpected.  What it is important to note, however, is that while some areas (mostly grassland and openings) were prone to frequent fires, most of the map deals not with the concept of "stand replacement", meaning a massive fire that pretty much burns everything from underbrush to canopy, but in fires that burned the understory and/or mixed levels of the canopy.

We would also do well to note the situation regarding southern California, where fire has always been quite misunderstood (including by your author, who had to correct this post on California a few times).  Southern California is often prime disaster candy for the evening news, complete with mudslides, earthquakes, and yes, devastating wildfires which take out those poor, unsuspecting multi-million dollar homes in Malibu and the San Gabriel foothills.  This has led to a scouring of the native chaparral ecosystem both by the developers, who want to rid the hillsides of what they see only as flammable vegetation build up, and the preservationists, who think that prescribed burns every year are good for the chaparral and prevent the manzanitas from getting too "overgrown and tangled".  The truth of the matter is that such fires have been devastating because of our control, both intentionally good and ill, over natural fire regimes in the wild, which, while intense (among the hottest in the world) are also not as naturally frequent as suspected (once every few decades to a century or more).  Thankfully, the fine folks over at The California Chaparral Institute have been doing their part to educate the public on fire issues in southern California (while also getting into a tricky and perhaps unnecessary battle with the USFS -see note at end-).  I mention the institute and focus so much on the example of California because it pretty much cuts to the core of what this entry is all about:

Fire, as you can see, is misunderstood by just about everyone.  Our climate is decidedly changing, and I leave my readers to argue about whether you think it is from the hand of man or a natural cycle, but the fact is that these massive wildfires, which supposedly all started from lightning, have also been impacted by poor wild land management in the past and accelerated by abnormally warm and dry conditions.  Again, this largely depends on the fire itself.  Colorado's High Park Fire is from an overabundance of fuel and favorable conditions.  The Duck Lake Fire in Michigan was accelerated by extremely favorable conditions despite having to burn through very wet bogs.  In both places we may see some truly wonderful regrowth in regions that should have eventually seen stand replacements, and we hope that the importance of defensible space and wise wild land management will set us in a favorable direction for the human factor in the future.  In any case, be it involving beetles, budworms, fire supression or fire spreading, too much of a thing can turn out to not be good.

I have every hope that as we continue to develop technologically and better our communication patterns and processes, we will also learn more about the greater world around us.  I have been fortunate in that my education and experiences have guided me into broader viewpoints in regards to conservation efforts, but at the same time, what I have seen in my travels across the continent in the last few years as well as my recent work in monitoring and controlling invasive species in southeastern Michigan has left me asking a lot of the big questions.  The plan for American Voyages includes perspectives on the whys as much as the whats of North America, so expect more coverage of environmental issues when they arise.  The purpose of this blog, after all, is to share with my readers what this continent is all about, and in doing so, we can all better educate ourselves on the world around us to both understand it and help prevent wasteful destruction.


Note on the United States Forest Service (USFS):


The USFS is a good organization that has had its ups and downs through a rather turbulent existence.  In order to even exist for much of their history, they have had to promote forests and grasslands as places of multiple use, to please both development and preservationist interests.  As noted, the California Chaparral Institute is currently in a position of thinking the USFS is out of its mind in regards to prescribed burnings and forest management in the San Gabriel Mountains.  I hope that both sides can overcome shortcomings in communication efforts and understand what needs to be done in the best interest of a very fragile southern California.  As such, I recommend checking out both the Institute's website:


http://www.californiachaparral.com/

And the USFS's publication on wildfires, which is a truly amazing resource:

http://www.fs.fed.us/rm/pubs/rmrs_gtr042_2.pdf

The Dramatic Virgin River Gorge

One of the more interesting stretches of main travel corridors in North America is Interstate 15.  I-15 starts its north-south journey at the United States-Canada border in Montana, where it follows the base of the Rockies before heading south into the mountains.  Eventually, it passes through the Great Basin alongside the Wasatch Range of Utah and through the Mormon-founded cities of Salt Lake, Provo, Cedar City, and St. George, at which point it descends into the Mojave Desert.  For the most part, I-15, like many other limited access highways, was engineered to provide for a relatively level driving experience that would eliminate both the speed-reductions inherent in climbing elevations by switchbacks and grades over 5% and also the engineering costs associated with such road design.  For the traveler seeking a much more dramatic and scenic route, the Federal highways and local roads are definitely the way to go.  This is not to say that the scenery is by any means boring.  As noted, I-15 passes through a complete column of North American landscapes, from grasslands to mountains to deserts and finally into the unique landscapes of southern California between Victorville, California and San Diego.  What it does mean is that the experience is a bit more manicured and serene rather than totally wild.

There are exceptions, of course.  Despite the best intentions of planners and engineers, the rugged western North American landscape eventually puts up a challenge even to modern convenience.  On such place is a short trip of less than 30 miles in extreme northwestern Arizona.  Separating the small portion of the Mojave that surrounds St. George, Utah is an abrupt rise of elevation on nearly all sides.  A few small tributaries of the Colorado River, and a larger one, the Virgin River, manage to cut through the western mountains of these surrounding peaks, often quite dramatically.  The canyons these water courses create form the only real passes into the rest of the Mojave beyond, and the builders of I-15 had no choice but the follow the impressive cut that the Virgin had made, at least without blasting and tunneling through a lot of land.  Even then, the work was expensive, and the drive would end up being nothing short of spectacular.  

At a few points the sky disappears and one is surrounded by huge walls of rock, which owing to its Mojave location, are quite devoid of much in the way of vegetation other than sagebrush, creosote, various cacti, and Joshua trees.  While the descent into St. George from the Great Basin to the north is the true entrance to the Mojave for I-15, this would be the first look inside the door into a grand entrance hall down a spiral staircase.  The best part is, such a view through I-15 is only scratching the surface, as the second and higher floors above the canyon walls rise further into truly lovely lands of a marriage between desert and forests.  I have only caught glimpses of this elevated world from the majesty below, but I was fortunate enough to come across a fellow blogger who knows the area quite well.  His post can be found here.

Anyway, with as dramatic a drive as this is, one imagines it would keep unfolding into far more dramatic territory than the edge of the comparatively mundane Great Basin that the driver has left behind to the north.  Well, it turns out that the Mojave shares the topographical characteristics of its cooler northern neighbor, which features large basins among high ranges.  Not a mile after exiting the canyon, one comes across deceptively flat expanses of desert.  I say deception is in order, because towering peaks loom once again around the flats for pretty much the rest of the trip through the desert.  Nevertheless, it is quite a contrast!

 The wild nature of the landscape also gets tamed at this point, and as one crosses the state line into Nevada, the seemingly ordinary town of Mesquite is encountered, complete with multi-lane roads and strip malls.  This being Nevada, they also have casinos and other unique diversions.  Americana, it seems, is never far away from an interstate highway, even deep in the wild west.

Sunday Afternoon Post: Beneath the Appalachian Divide

Much like the great crossing of I-70 over the continental divide in Colorado, the passage of I-70 over the divide between the Gulf and Atlantic drainages in Pennsylvania goes through a tunnel.

Don't worry, both lanes are for the same direction, and yes, they could stand to do some maintenance on this tunnel, and no, I don't normally use a GPS when driving as I think they make navigators sloppy.

Making Sense of the Whole

Thus far on American Voyages we have been from Atlantic to Pacific, down well into central Mexico, and up to the spruce wilderness of the Canadian Boreal forests.  While this is a good thing for people wanting to see environments and landscapes very different from their own, such a jumping around approach tends to get both the reader and the writer a bit lost.  At the same time, a strange image of a continental mosaic pops into mind, with a desert occupying on square, a forest the next, and then some huge lake after that.  In truth, our landscapes tend to merge together rather nicely, with some species of flora and fauna being found in places as seemingly different as the Ottawa Valley and the mountains of Oaxaca, and a species like Silver Maple (Acer Saccharinum) can be found growing next to either a boreal spruce or a subtropical palm tree.  That said, one will be hard pressed to fail to notice a difference between a cypress swamp in Mississippi and an open stretch of shortgrass prairie in Montana.  So, how about an overall picture?  I found an excellent mapping resource just last night at BONAP, the Biota of North America Project.

For now, they seem to be focused on the United States, but they intend to expand their mapping projects to Canada and (gasp!) Mexico.  They have absolutely wonderful maps when it comes to the art of documenting transitions between ecozones (known as tension zones), so let's take a look at two.

Map the first, Tension Zones Between North and South:

As you can see, the lines are not a continuous path from coast to coast, nor should they be.  Changes in scenery from Canada to Mexico and the Gulf tend to be dependent on elevation and proximity to the moderating effects of large bodies of water as much as latitude.  Where lines disappear, this is because there is a ton of overlap between existing regions, as is the case in eastern Oklahoma, where east meets west meets south meets northeast meets, etc. etc.  Some of the lines should make sense immediately:

South End of Lake Huron to northern Minnesota: Southern limit of Boreal species.  North of this line the eastern pines, spruces, and birches are common.

Central Kentucky to Tulsa, Oklahoma: A distinct edge of some of the interior South/subtropics.  South of this line, almost exactly in fact, you can find Baldcypress (Taxodium Distichum) and Water Tupelo (Nyssa Aquatica) as well as many other southern species.

Richmond, Virginia to Macon, Georgia: Another distinct edge of some of the coastal South/subtropics.  On the Atlantic side of this line, which roughly coincides with the "fall-line" on which the great cities of Richmond, Raleigh, and Columbia were built, you can find things like the southern pines, a good helping of broadleafed evergreens, and even some palms.

Also of note is that even though this is a latitude-oriented map, the lines bend significantly south when encountering mountain ranges, and the red gets really dense in those areas.  The sudden change in elevation can create conditions which contrast very sharply between mere miles, a contrast which is perhaps the sharpest in extreme southwestern Utah, where the Great Basin and its plentiful acres of sagebrush and junipers quickly give way to hot desert species, like Mesquites, Creosote (Larrea Tridentata) and Joshua Trees (Yucca Brevifolia), as well as the sudden appearance of cultivated palms.  Other good examples of sharp contrast include the Sierra Nevada range of California, where giant trees clash with lower elevation grasslands and deserts, as well as the southern Appalachians, where northern pines and spruces well south of their normal broad range grow in close proximity to southern pines and other trees.

Map number two shows us how Tension zones fall between east and west:

While it might seem obvious that lines would be drawn between the mountains, plains, and eastern forests, some of them might require a bit more explanation.

The line stretching from Manitoba to near Houston pretty much serves as an excellent line between east and west in general.  Though numerous guide books insist on dividing species at the base of the mountains (the line from Alberta to El Paso, Texas), the truth of the situation is that the open plains west of the tallgrass prairies are really a gateway to the west.  Yes, you can still find eastern species creeping out along the rivers, but the overall look and lack of water in the landscape is pretty effective at telling travelers that they have left behind the watered east.  The line to the west of this, the base of the Rockies, pretty much takes you away from the land of the maples and oaks and into the land of junipers, pines, and fun things like a diversity of cacti, yuccas, and more cottonwoods than you can handle.  The line to the east of this, from Minnesota to the Gulf, is pretty much the eastern boundary of open prairie, where the grass admits that it can allow the oaks and other trees to win the eternal struggle of dominance.  Again, these are not sharp lines.  Forests pretty much cover a ton of Arkansas, Missouri, and Oklahoma.

The line from British Columbia to southern California indicates the sharpest contrast of all.  On the eastern side lies deserts and the mountain forests which mock them from above.  To the west of the line, which roughly coincides with the Pacific Crest along the Cascades and Sierras, is an entirely different world of temperate rainforests, chaparral, towering redwoods, sequoias, firs, and Sugar Pines (Pinus Lambertiana). You know, the land that people tripped over themselves to get to when heading to make a new life out west.

If the last sentence seemed significant at all, that's because it probably is.  Cultural differences on this continent have a lot to do with differences between climate and ecosystems.  The sorts of crops one could grow in each region definitely birthed cultural differences, especially between North and South or Midwest, Nearwest, and Northeast (Corn vs. Cotton).  An open range created a new sort of rough and ready culture of the high plains and intermountain west.  Ontario is roughly divisible between its northern and southern parts, or between Shield and Carolinian forests.  The desert lands of northern Mexico can seem like a different world from the tropics of Oaxaca and Veracruz.  Southern California decidedly is on another planet.  Sometimes the differences in land and people are sharp, even as they are often less clear.