Did the American Bison limit carnivorous plant distribution in North America?

[noah]

A glance at a map of the distribution of carnivorous plants in North America reveals that a large part of the continent is almost completely devoid of CPs. Here I've mapped the distribution of Drosera anglica (in yellow) and the genus Sarracenia (red).



As you can see, the entire central part of the continent, from the Appalachian Mountains to the Rockies, is completely bare of these species. This, even though historically that area encompassed a diverse array of habitats, including grassy plains, mountain glades, and meandering rivers.

Now, the impact of large, herd-forming herbivores on wetlands and other fragile habitats has been well-documented. Carnivorous plant habitats, too, have long suffered from the introduction of domesticated cattle. (I documented an example of the negative impact of these clodfooted composters here).
One wonders whether some prehistoric cousin of the modern Bos taurus might have decimated carnivorous plant populations of ore, turning once-lush marshes into dry prairies and restricting carnivorous plants to their present distribution? The American Bison, of course, springs immediately to mind!



This majestic lumbering ungulate of the American plains would have unleashed decimation on fragile wetlands! Although hunted to near extinction in the late 19th century, upwards of 60 million bison are thought to have blanketed the plains before the wholesale slaughter began.

Here I've mapped the historic distribution of the American Bison on top of the distribution map from above:



Interestingly, the outline of American Bison distribution follows that of the mapped carnivorous plant species quite well. Naturally, correlation does not indicate causation, but could bison have played a role in limiting the distribution of carnivorous plants in North America? Who knows...

 

[jimscott]

Those stampedes must have been murder on those poor plants!

 

[herenorthere]

You can use the same evidence to argue that bison are terrified of CPs and did their best to avoid places where CPs live. Or maybe their preferred habitats don't overlap much.

 

[rattler]

the whole north central part of the bisons range(MT, the Dakotas and WY) has minimal..................very minimal decent CP habitat...........there are no bogs, the water is generally high in minerals and fairly alkaline..........central/west TX, NM and AZ are prolly quite similar as is eastern CO and western NE and KS...................

 

[Finch]

The largest area of wetland habitats for cp's in the plains is the prairie pothole region. That areas was carved out by the most recent glaciations and is not connected to other suitable habitats, that would make it nearly impossible for cp's to colonize it. Other than that, wetlands are few and far between, separated by miles. Very unlikely a cp could transverse these areas. It is also notable that sphagnum is very rare and does not occur in the dense mats of sphagnum peat found out east. Mostly muck is prevalent, at least where I live. Lastly, the wetland flora in these areas are all characteristically tall and intergrades seamlessly with the wet tallgrass prairie flora, also dominated by very vigorous grasses and herbs. Any low-growing cp’s that found the right growing media would surely be out competed by the tall grass for light. Wet areas even in drygrass regions can support tallgrass flora. That just does not bode well for CP persistence... or sphagnum, for that matter.

Not to mention that more than half the wetlands do not always stay wet. Water levels fluctuate widely due to frequent droughts, leaving areas that were moist one year high and dry for the next 5. There is no consistant water level here, something the cp's out east just cant handle. Ok they can survive for a time, but when the next big drought comes and drys up their home for a few years, they wont be there waiting when the water does return

 

[joossa]

Finch summed it up nicely. Interesting study, though.

 

[Not a Number]

You'd have to overlay Plains Indian populations too, which often started brush fires to stampede the bison. These fires would be beneficial to CPs. Although Plains Indians tended to be nomadic, following the bison herds they would still have some impact on the environment.

A very interesting observation nonetheless.

 

[jimscott]

So it sounds like their respective habitats just didn't coincide.

 

[noah]

Yeah, that's probably the case. Of course, things aren't necessarily that black and white: Animal and vegetable communities certainly do have major impacts on habitats (De-vegetation seeds desertification, etc.). In the meadow I described in the post I linked to, a wet fen was being transformed into a dry patch of European grasses and clover.

In any case, I had just noticed the interesting distribution correlation and put it up here as much for the laughs (hence the bison chewing on S. 'Leah Wilkerson') as for any serious discussion.

noah

 

[JB in Utah]

Very interesting theory, I bet that there is some validity to this.

 

[Wire Man]

The vast majority of the Southwest and Northwest are too dry for CPs. I dug postholes in South Dakota once, and the auger turned the ground surrounding the bit into glass. It was that hard and dry. There's not much in the way of bog plants that can survive out that way.