Subj: Species to planet-wide Conservation
Shueyi at AOL.COM
Tue Jan 12 08:56:23 CST 1999
In the spirit of answering some of the direct questions I received following
my recent post I offer the following to the group - a somewhat lengthy
elaboration. I'll get back to individuals later as I ponder things a little
I think that there are two basic underlying philosophies behind the discussion
regarding how targets are selected for conservation. Neither is right or
wrong, but these philosophical differences influence the perceived goals of
conservation as well as how people (and organizations) approach achieving
those goals. These philosophies produce two radically different end products.
The first outlook (and the one that seems most current in academia) is that
"There is a biodiversity crisis looming that can't be averted". Thus, while
we concede that there will be major extinctions in the immediate future, we
must figure out how to minimize the damage. We therefore, must preselect
those species or regions that have the most conservation value, and
concentrate our resources on those targets. (note that I may be minimizing
some aspects of this philosophical approach because I personally don't buy
We develop tools that help us identify that what is important to us
("us" usually being the particular researcher in question). For example,
phylogeny can provide insights into and identify evolutionarily unique
entities. We can look at genetic distance between lineages. We can identify
biogeographic patterns and regions with high endemism. But ultimately, we
have to make value judgments - impose the human perception on evolutionary or
biogeographic patterns - to select those that are most important. For
example, the coelacanth rears its fins, as it is such a novel evolutionary
experiment in underived morphology. The World's smallest mammal, the
bumblebee bat, actually kicked off this thread. Both are interesting species
that have value, especially to evolutionary biologists. Or perhaps we are
fond of the Caribbean Islands, because of their high level of endemism. Or
perhaps the Amazon Basin supports a million species per square kilometer,
while Great Britain has only one-thousand per unit area - thus we "know" where
conservation resources are best spent.
The "product" of this approach is a list of taxa (usually individual
species), species-rich regions, or biogeographic regions (e.g. the northern
Andes, the Amazon Basin forests) that are most important. They are usually
"pointers" designed to guide others in their effoprts, and no specific sites
are generally mentioned - just species and regions that are "important".
The second philosophy is radically different. "There is a biodiversity crisis
looming and it is our duty to avert it". Thus while we concede that there may
be major extinctions in the near future, we believe that it can largely be
avoided if we act quickly and decisively (this philosophy is not so current in
academia but tends to be more persuasive with conservation groups on the
ground). This approach places equal value on all species.
This group develops tools that help it capture all levels of biodiversity (as
best as you can do that). Of utmost importance are the identification of a
system of "coarse filters", conservation targets that if protected will
capture the bulk of diversity in a region. For example, TNC developed the US
National Vegetation Classification system which identifies over 4000 discrete
terrestrial plant communities for the US (this is an even fuzzier taxonomic
excersize than is real taxonomy, and human judgement is a large component of
this process). The idea behind these coarse filters is that if one dominate
group of organisms seems to sort out along environmental gradients into
recognizable associations, then other groups likely sort themselves out along
these gradients as well. Thus, you are very likely to conserve terrestrial
nematodes and bacteria by conserving all recognizable terrestrial plant
communities at an appropriate scale that also conserves the associated animal
communities (usually area sensitive vertebrates are used to make this call).
Similar community classification efforts are underway for tropical America as
well aquatic and subterranean communities in the US.
The coarse filter is then stepped down to the unit of conservation - actual
sites that support populations of species. Site are chosen based on their
ecological integrity (using a variety of tools ranging from remote sensing to
assessments of hydrologic function, abiotic processes, etc). Sites are ranked
based on a human assessment of how defensible they are - an attempt to
separate viable sites from non-viable habitat fragments.
The concepts behind ecoregional mapping are also being used as tools to
capture geographic variability of community types and to broaden the
biodiversity "capture rate" at the species and population (genetic) level.
Ecoregions are based on abiotic gradients that seem to influence the
expression of biodiversity (apparently at all the levels of organization).
By selecting sites which conserve all community types across all ecoregions
(=across abiotic gradients), you should capture the vast majority of species,
as well as the range of genetic variation that characterizes each species.
And of course biogeography is factored into the mix. Cloud forest
communities will likely be classified broadly enough that by themselves, they
would not pick up the levels of endemism encountered in the Andes - thus cloud
forest targets need filtered though known biogeographic patterns.
In addition, there are individual species are indeed imperiled and which
may be missed by community targets (so called fine filters). Where knowledge
permits, these are targeted independently (at minimum, such species are
"checked" to make sure that they were picked up in the sites selected based on
Finally, people and organizations with this philosophy do prioritize
conservation targets. But this prioritization is based on threat (not value).
Certain conservation targets are so imperiled that if we don't act now, we may
lose singular opportunities. Thus, in the spirit of avoiding the biodiversity
crises, a human perception of threat is added to the mix. For example, the
generic wet/mesic prairies of the US are actually more imperiled than are the
generic rain forests of the Amazon Basin. "Mesic Tallgrass Prairie" has been
reduced in extent by 99.9% while forest loss in the Amazon is around 30%.
Both must be conserved - but based on threat, time is really short for saving
pieces of good old, species-poor, prairie. Atlantic Coast rain forest
communities in Brazil are more threatened than are interior forests. And so
The "product" produced by this approach is a list of actual sites which, if
conserved will achieve explicit conservation goals (usually stated as some
number of redundant units per conservation target with explicit geographic
representation goals built in). This list of sites carries two "grades". An
assessment global threat to the target, such that those targets that most need
attention are (hopefully) conserved first, and those that can wait are
conserved on a more opportunistic basis. (But remember that the ultimate goal
is conservation of all sites identified). And a measure of ecological
integrity, such that for "common" targets you would expect that easily
defended sites make the cut while the beat-up examples are not targets. But
many of the most imperiled conservation targets also occur in pretty bad
situations - this ranking allows you to select among sites if you have that
Now a few words from my sponsor: The Nature Conservancy (the US organization -
not the British one from which the Ecological Society of America pirated our
name) has two explicit statements that guide every aspect of its operations -
its mission and its conservation goal.
"The Mission of The Nature Conservancy is to preserve the plants, animals and
natural communities that represent the diversity of life on Earth by
protecting the lands and waters they need to survive. The Nature
Conservancy's conservation goal is the long-term survival of all viable native
species and community types through the design and conservation of portfolios
of sites within ecoregions."
Thus, you can see why the Conservancy cannot accept planning strategies that
select "high value" targets at the expense of others.
It all has value.
Director of Conservation Biology
Indiana Office of The Nature Conservancy
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