Tight But Loose – just what is “biodiversity”?

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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:


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:


These are fascinating discussions that will run and run, I have no doubt.


*I’m fond of bringing musical examples into these blog posts 🙂


9 thoughts on “Tight But Loose – just what is “biodiversity”?

  1. Brian McGill

    Thoughtful reply Jeff.

    I’m still stuck on your example of the marsh though. Since phragmites only grows in wetlands, we probably still would have a woodland, a grassland, and a marsh, and at a finer grain I believe phragmites can only grow in the high marsh, so the low/high marsh distinction would still be retained – its just that the species in the high marsh would be different.

    How does biodiversity at the ecosystem level let us argue against this? (nb: phragmites might or might not reduce the number of species in the marsh component and if it does I well understand how that would let us argue against phragmites at the 2nd/species level).

    1. jeffollerton Post author

      Hi Brian – as I understood your rhetorical argument about phragmites was from an ecosystem services perspective, not biodiversity per se: phragmites is better at flood defence, so let’s plant that on the salt marsh. Have I interpreted that correctly? So then it comes down to the status of the phragmites – is it native or not? I know that there is disagreement about this in North America. If it’s non-native and we plant it at the expense of native species/habitat types then to my mind it’s a net loss of biodiversity.

  2. rcannon992

    Very interesting article and links. I can understand that some people resent the idea of monetising nature, but it can be useful in preserving, for example insignificant creatures which might be considered ‘worthless’ in the minds of money minded politicians and developers. But nature has to compete with mankind’s sprawl in this rapidly expanding world, and putting a price on something is one way to demonstrate the value of nature. Of course many aspects of nature are precious to us in an aesthetic or non-monetary way (as a source of joy, inspiration and relaxation etc.) although economists have a way of valuing this attributes too! E.g. by asking people what they would be prepared to pay for them!
    I understand however, where Monbiot is coming from but the mistake he makes, I think, is to assume that “Rarely will the money to be made by protecting nature match the money to be made by destroying it.” On the contrary, when all of the functions and benefits – not just to humans – of nature are captured, as for example in a pristine rain forest, then the value of the intact ecosystem is far greater than the value of its products when cut down. In doing such cost benefit studies it is vital to include relevant, long tern perspectives and a full accounting of the benefits provided. The only caveat is that we probably don’t have a complete understanding of all of the benefits – or ecosystem services – which exist.

  3. Steve Hallam

    Jeff, I have recently come across your blog and find it fascinating. I have also recently come into contact with the debate around protecting / valuing ‘nature’ – how best to achieve this, natural capital, ecosystem services and so on. (I am a freelance market researcher with an amateur interest in conservation – sorry!). One of the particular issues that interests me is how to provide ‘nature’ with more weight when messy political trade off decisions are being taken by governments. From my perspective, as you might expect, I see the ability to assign a value to nature (or a specific bit of it) as something that should help to increase the importance that is given to nature, relative to, say, a new road / housing estate / quarry. I presume that this is where the interest in natural capital and ecosystem services originates from.

    But, as I think you agree, the value of ‘nature’ to people has an emotional element (those people photographing lupins in Iceland) as well, which could conceivably be of greater perceived value to the general public than the practical economic ones provided by ecosystems services. Bearing this in mind, one thing I’ve noticed in the writings of ecologists and environmental campaigners / organisations is a complete lack of interest in trying to measure (or even thinking about measuring) the value of these emotional benefits.

    From my background I find this surprising and disappointing. This situation contrasts markedly from how the brand building industry works. Marketing people know that strong brands are worth more than weak ones (and, of course, the value of these differences can be measured), and that strong brands tend to be those that provide emotional benefits to their users, in addition to functional benefits – think of Apple. So measuring the added value provided by emotional benefits is very important to marketers.

    As a result the marketing industry has developed a range of powerful and effective research tools to measure, and price, the value of emotional benefits. (Two key ones are Brand Price Trade Off and conjoint analysis.) In fact this is pretty much at the heart of what the marketing industry focuses on. None of these research tools are perfect, but my experience of using them makes me feel that they would certainly enable an approximate value of the emotional value of nature to be estimated (although this might only be for certain defined circumstances, at least at first). I would have thought that doing this would strengthen the case for protecting nature. Of course, no technical or analytical tool can overcome power imbalances within flawed political decision taking processes. The key test is whether or not they act to redress these imbalances to some degree.

    Or have I missed something?

    1. jeffollerton Post author

      Hi Steve – thanks for the comments. I agree, emotional (or spiritual as it’s sometimes referred to) valuation of nature is not often done. There are some examples out there but they are few, and don’t usually put a monetary valuation on it. The sort of approach that you’re suggesting could be very interesting.

      1. Steve Hallam

        It just needs someone to do it. BPTO could be used to see how much people would value a day in the country / at Minsmere / whatever, in relation to (and this is the key bit) a day at Longleat / a National Trust property / Legoland / whatever.

        More interesting could be to use conjoint analysis, because this is powerful and flexible, and would force consideration of ‘nature’ as a product with constituent attributes (which I appreciate some (most?!) conservationists would regard as an anathema). In fact the need for this conceptual definition would be the most challenging aspect. Ideally you would commission some qualitative research first, to generate an understanding of what these attributes should be. Then the conjoint enables you to measure what each one of these attributes is ‘worth’, and (by combining these in different ways) what is the overall value of different forms of nature experience.

        Other than this conceptual work it would all be pretty straightforward. As you ask, costs would be £5-10k for the qual., £10-15k for a BPTO, and perhaps £12-20k for a conjoint. So not peanuts, but not a massive amount bearing in mind how novel it would be.

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