Nature | Editorial http://www.nature.com/news/an-elegant-chaos-1.14849
An elegant chaos
Universal theories are few and far between in
ecology, but that is what makes it fascinating.
11 March 2014
To some scientists in other fields, ecology must
seem relatively straightforward. Many of the
organisms live at a very human scale and are easy
to access, especially in community ecology.
Ecologists do not need special equipment to see
and count elk. There are no electron microscopes,
space telescopes or drilling rigs that can go wrong. Easy.
And yet, ecologists know that their subject can
prove as troublesome as any other. Ecology would
be easy, were it not for all the ecosystems
vastly complex and variable as they are. Even the
most austere desert or apparently featureless
moor is a dense, intricate network of thousands
of species of photosynthesizers, predators, prey
animals, parasites, detritovores and decomposers.
As naturalist E. O. Wilson put it: A lifetime
can be spent in a Magellanic voyage around the
trunk of a single tree. And not all of what one
might learn from such a voyage would be
transferable to the next tree. History, chance,
climate, geology and increasingly human
fiddling mean that no two ecosystems work in the same way.
Scientists like to impose structure and order on
chaos, and ecologists are no different. Ecology
has its grand theories, but they are riddled with
conditional clauses, caveats and exceptions.
There are clear patterns at the global and
single-species scales, but the middle ground is,
as biologist John Lawton affectionately put it in
1999, a mess. It is doubtful that the
generalities that underlie the complex patterns
of nature will ever be phrased succinctly enough to fit on a T-shirt.
This complexity is demonstrated by work that
questions a famous and elegant trophic cascade
in Yellowstone National Park, Wyoming, discussed
on
<http://www.nature.com/uidfinder/10.1038/507158a>page
158. The theory goes that wolves, restored to the
park in the 1990s after decades of absence, scare
elk away from certain areas. That has a knock-on
effect for the rest of the food chain, allowing
aspen and willows to flourish after decades of
being browsed nearly to death. But studies in
recent years suggest that wolves alone do not
control the ecosystem. Other factors the
presence of beaver dams and grizzly bears,
weather, hunting by humans and even climate
change also affect the elk population and the growth of trees and shrubs.
It would be useful to have broad patterns and
commonalities in ecology. To know how ecosystems
will respond to climate change, or to be able to
predict the consequences of introducing or
reintroducing a species, would make conservation
more effective and efficient. But a unified
theory of everything is not the only way to gain insight.
More ecologists should embrace the non-predictive
side of their science. Teasing out what is going
on in complex systems by looking at how
ecosystems evolved, and by manipulating the
environment in experiments, is just as much a
science as creating formulae for how ecosystems work.
If ecosystems all worked in the same way, they
would lose much of their mystery, their surprise and their beauty.
Paradigm shifts, after all, are rare in ecology.
Debates are often resolved when competing
concepts combine, rather than when one pushes the
other completely off the table. Take the
contrasting ideas of top-down regulation of
ecosystems by carnivores and bottom-up regulation
effected by the nutrition available from plants.
The field is slowly working towards an integrated
theory to predict when the top will rule and when
the bottom will be in charge and that theory
will take the time to consider the middle players, the herbivores.
Other ecological debates have followed a similar
path. Disagreement over whether complex
ecosystems are more or less stable than simpler
ones, for example, is also settling to a consensus: it depends.
Useful practical predictions need not stem from
universal laws. They may come instead from a deep
knowledge of the unique workings of each
ecosystem knowledge gained from observation
and analysis. Proposing sweeping theories is
exciting, but if ecologists want to produce work
useful to conservation, they might do better to
spend their days sitting quietly in ecosystems
with waterproof notebooks and hand lenses, writing everything down.
Ecological complexity, which may seem like an
impenetrable thicket of nuance, is also the
source of much of our pleasure in nature. If
ecosystems were simple puzzles that all worked in
the same way, they would lose much of their
mystery, their surprise and their beauty. A lot
of conservation work aims to protect the
complexity and variability that makes ecosystems
so hard to understand, and indeed to conserve.
Ecological rules are not the only reasons to
promote conservation and fight extinctions.
Sometimes we can argue for the conservation of
particular species because ecology provides a
scientific basis for it. At other times, we make
the argument because there is a good chance that
ecology will soon catch up and explain why the species are important.
But even if some predators do little but sit at
the top of their food pyramids, creaming off a
few herbivores, would we really want to live in a
world without them? Answering that question really is easy.
Nature
507,
139140
(13 March 2014)
doi:<http://sfx.umd.edu/cp?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:journal&__char_set=utf8&rft_id=info:doi/10.1038/507139b&rfr_id=info:sid/libx%3Ausmai&rft.genre=article>10.1038/507139b