Professor Jeff Ollerton explains what is meant by the term 'biodiversity...
Ever since I set up the
Biodiversity Blog in 2012 I’ve had it in mind
to write a post asking the question “Just what is “biodiversity”?”, but
have never quite got round to it, there’s been too many other
interesting and important things to write about on here! This week over
at the Dynamic Ecology blog Brian McGill has beaten me to it with a
really interesting post entitled:
Biodiversity and pizza – an extended analogy leading to a call for a more multidimensional treatment of nature.
I’m not entirely sure that the pizza analogy works, it’s a little
tortuous, but none the less the post is provocative and interesting, and
has generated a lot of comments. I strongly recommend it.
In the interests of recycling, and because the readership of my blog
only overlaps partially with that of Dynamic Ecology, thought I’d
restate a few things that I brought up in the comments to Brian’s post
(but this certainly won’t substitute for going over and reading it
yourself”.
One of the questions that Brian asks is: “Is biodiversity a useful
term or has it outlived its usefulness?” It’ll come as no surprise to
readers that I like the word “biodiversity”: I used it for the title of
my blog and for my professorship, because it captures a lot about what I
value in the natural world, and because it’s a term that I’ve
(professionally speaking) grown up with. To my mind it is an umbrella
term that can mean different things to different people; some see this
as a disadvantage but I think that, as long as we qualify precisely what
we are referring to, using “biodiversity” in a loose way is not a
problem. Perhaps an appropriate analogy is with politics: if someone
describes themselves as a “conservative” or a “socialist” or a
“liberal”, those terms cover huge internal variation and political
scope, but it’s not a problem because it broadly describes the beliefs
of that individual.
As an instance of when “biodiversity” may not be a useful concept for
nature conservation, Brian gives an example of salt marsh, often areas
with rather low species diversity, as being of low priority for
conservation because they are poor in “biodiversity”. But this ignores
the fact that all of the “official” definitions of biodiversity
explicitly include diversity of habitats/communities/ecosystems/biomes
in a defined geographical area. For example the United Nations
Convention on Biological Diversity defines it as:
“the variability among living
organisms from all sources including, inter alia, terrestrial, marine
and other aquatic ecosystems and the ecological complexes of which they
are part; this includes diversity within species, between species and of ecosystems.” [my emphasis]
Thus destroying an area of salt marsh may indeed result in few
species being lost, but it would be a significant loss of biodiversity
at that higher level
of community/ecosystem, if a region has only salt marsh, woodland and
grassland in it: in essence you’ve lost one third of your biodiversity
because you’ve lost one third of your habitats.
Something that’s occurred to me over the last couple of days of
reading comments and thinking about the questions that Brian posed is
that “nature” and “biodiversity” are not actually synonymous at all.
When people say they like “being in nature” or they “value contact with
nature”, what they are usually saying is that they enjoy landscapes,
seascapes, changes in the weather, being out of doors, etc., things
which are not strictly part of what we understand as “biodiversity”.
Likewise, “protecting the environment” includes a whole set of
non-biodiversity related questions and actions such as air and water
quality, wastes management, sustainable use of resources, etc., much of
which may not directly affect biodiversity at all.
“Biodiversity” has a specific meaning, as the definition above shows,
even though that meaning can be broadly defined. Which sounds like a
contradiction, but it’s not – and brought to mind the title of the Led
Zeppelin fanzine: “
Tight But Loose”*.
Biodiversity as a concept and as a field of research and action
involves so many different types of stakeholder (ecologist, botanist,
zoologist, artist, conservationist, activist) that (as I said) it
provides a useful (loose) umbrella. Problems only occur when people use
different tight definitions and talk past one another.
The other aspect to Brian’s post is around the pros and cons of
valuing ecosystem services, which is a much bigger argument in some
ways, and I’m going to point readers to two blog posts, one recently
from Steve Heard which I think is a very nice, concrete example that
captures a lot of the uncertainties that Brian describes:
https://scientistseessquirrel.wordpress.com/2015/08/04/invasions-beauty-and-ecosystem-services-a-conundrum/
The second is one of mine from last July related to the value of valuing nature, which was prompted by the Costanza
et al. update paper:
https://jeffollerton.wordpress.com/2014/07/27/how-do-we-value-nature/
These are fascinating discussions that will run and run, I have no doubt.
*I’m found of bringing musical examples into these blog posts
:-)
This blog post was first published here.
