The Bigger They Are, the Harder They Fall

It seems that in every paleologic era, at least since the chordates evolved, huge animal species have evolved, found a relatively comfortable niche in a stable environment, and then WHAM!  Some ecological disaster happens, there's a mass extinction, and then the little guys fill the empty niches, lather, rinse, repeat.  Bjorn Carey, in a Livescience article, takes a look at some of the reasons why the big guys are predisposed to extinction during a climate impact.  The usual reasons are covered: anatomy is too specific to its niche causing large initial dying off; not able to breed and adapt as quickly as the smaller species (large animals usually have longer gestation, weaning, and maturation periods; and specific environments may have been impacted, for example land vs. ocean in the Cretaceous, allowing water or coastal species to evolve and fill empty niches further inland.

But the new thing reported in this story is the idea that mutations may arise in a population, much larger than average, in which the median species cannot compete for resources, causing a boom-bust cycle in an ecosystem that we see in modern times.  The well-document cases of boom-bust were caused by humans killing predators for harassing livestock, causing a huge boom in their usual prey, and then a massive die-off when the prey's food supply is exhausted.  In those cases, humans were the initial cause of the boom-bust, but in times past, an original large animal mutation precipitated the boom-bust cycle.

So, these days, humans are the Super Predators, which is nothing new in our planet's history, but the difference is that we are now aware of our impact on ecosystems and can figure out our proper role in balancing our needs and preserving a certain habitat, or whether we should even care about an ecosystem's development into one of our choosing.  Extreme preservation wants to leave no human footprints at all, preserving all species and environments as if humans were never there.  Extreme economic development posits that the land is under human ownership and all of its resources are to be managed with profit in mind.  The balance comes in whether the species in a specific habitat are worth saving, and resource management with conservation in mind.

That sounds extremely arrogant and pragmatic.  Shouldn't we be saving all endangered species?  The answer is, simply, no.  What if a species were going extinct without any influence from humans?  Should we interfere?  Or should we let Nature tend to its business?  A good example of humans mucking up the environment after trying to "save" it was the change in forest fire policy in the National Parks.  Before the 1990's, forest fires caused by lightning were regarded as natural events and allowed to run their course, while directing fire fighting to preserving key structures.  But after the Yellowstone Forest Fires of 1988, policy changed to stop all fires in National Parks.  This was based on economics (tourism) and short-sighted environmental policy (save endangered animal species).  But all forests consisting of large pine species (redwoods and sequoias) rely on forest fires for survival.  The fires clear out smaller tree and plant species, allowing for less competition for resources with the larger trees, and the large pines evolved so that fire is the only thing that can eat through their protective bark and release their seeds.  Smaller pine species developed cones, relying on small mammals to release and distribute their seeds, but the big guys did not.

Now, we have more fires, more fuel (brush), and we spend more resources fighting these fires because they get so large, they threaten private housing developments.  The large pines' life cycles are so long, 20 years of human interference are likely not going to affect their continued existence, but after 100 years, we may have to worry.  What if a new administration comes in and decides we spend too much on clearing brush and we should let logging companies come in and build roads and do that for us.  Oh, wait, that already happened.  So, because we wanted to save the trees in 1988, we may end up losing all of them, to competition with brush, not reproducing, and having them all cut down without proper regulation for renewal.

Ecological examples tend to be have a lot of details, which only makes sense since ecosystems really are all tied together, until they get to a desert, or ocean, or a big ass mountain.  My opinion is that Environmental Impact Reports have become too adversarial, instead of taking the balanced view that humans and our projects are also part of nature.

(note: I'll be applying the links to all the examples a little later.  As I said, ecological examples have a lot of details, and it takes time to apply all the evidence.)