Just what is resilience, anyway?

Last week I organised a workshop bringing together researchers interested in resilience from across the Biodiversity and Ecosystem Service Sustainability (BESS) programme run by NERC. I’ll write about things that came out of it over the next few weeks. Here is my first missive


“Is it real? Is it an obscure object of desire?” my boss Adrian asked during our workshop . Given that  nearly 20 years ago there were 163 different definitions of ecosystem resilience, it is perhaps no wonder that we we having a few problems. Part of this problem is that resilience is a boundary object – a term that is interpreted differently by different communities. During our meeting it became clear, for example, that ecological researchers and policy-makers did not necessarily mean the same thing when they were talking about resilience.

Generally, researchers see resilience as a property of a system. Being researchers, we want to quantify this resilience. However, it turns out that resilience can’t really be viewed as a single thing, since it is made up of a number of different qualities. Along with the expert guidance of Volker Grimm our workshop came up with 3 different elements that are important when assessing resilience for research:

  1. Recovery – The return of a variable to the reference state after a disturbance.
  2. Resistance – A variable staying essentially unchanged despite disturbances.
  3. Persistence – Persistence of the system over time.

Using these three different properties allows researchers to look at different aspects of resilience and compare across systems. Making such comparisons is actually very difficult due to constrains on time and funding, as well as logistical problems. For example, to compare resistance of different communities you would ideally apply different intensities of disturbance in different locations. This may be possible in some relatively ‘fast’ systems such as grasslands but it is unlikely that you would get permission to do this to a woodland where you might have to cut trees down. In order to resolve this, mechanistic models can be exceptionally useful for investigating different scenarios of change. Combining this with empirical data collection in the same system can help us gain a more detailed understanding of resilience. This is something we are aiming to do in our current project as part of my post-doc work.

Policy makers on the other hand generally view resilience as a goal. Recently policy documents have begun to mention the importance of resilience. For example, one of the Convention on Biological Diversity’s 2020 aims is to:

By 2020, ecosystem resilience and the contribution of biodiversity to carbon stocks has been enhanced, through conservation and restoration, including restoration of at least 15 per cent of degraded ecosystems, thereby contributing to climate change mitigation and adaptation and to combating desertification.

Similarly the environment white paper in published by the UK government in 2010 mentions resilience 36 times and the Welsh government is aiming to create:

A biodiverse natural environment with healthy functioning ecosystems that support social, economic and ecological resilience and the capacity to adapt to change.

It is also included in US and Australian policy. So in the case of policy-makers it becomes clear that resilience is seen as a target. While for researchers resilience can mean something very specific policy-makers probably consider it to be closest to the previous definition of persistence.  At our workshop there were plenty of anecdotes about policy-makers saying things like “resilience is the new sustainability” and telling civil servants to “stick some resilience in your report, it’s the new thing.” There were also reports that some policy-makers wanted the production of maps of resilience. I think this is potentially dangerous. Given that the ratio of empirical work to conceptual stuff/reviews and perspectives pieces is about 1:1000 we simply don’t have enough evidence to produce these maps at the moment. If push came to shove then we could probably come up with a best guess based on ecological theory, but even then there would be all sorts of caveats.

I think it’s clear we will never reach a point where there is one definition of resilience that fits everyone’s need. However, when we talk about resilience we need to be clearer about what we mean by it. So next time you use it in a paper, for the love of god, define it.

*Edit #1 – I just came across this nice post by Jeremy Fox on defining stability concepts in ecology, which, if might be a useful companion piece to what I said here.

*Edit #2 – Ambroise Baker who helped organise the workshop with me has a short summary of the meeting over on the Lake BESS blog, you can see that here.

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10 thoughts on “Just what is resilience, anyway?

  1. Look forward to reading more about the meeting Phil. Resilience and stability are on our mind at the moment as we have been trying to publish what is one of the first experimental tests of “stability” in plant-pollinator networks, but have come across resistance from journals because its based on a single site manipulation plus a control. During the writing of that manuscript we had long discussions about what we really mean by “stability”, it was very enlightening. Interesting point that scientists and policy makers see them as properties versus targets.

    1. Glad you found this interesting Jeff. I found it bewildering that at the meeting there were so many discussions about definitions – but I guess that’s inevitable when you have people from so many different systems. We are just preparing a meeting report to go into the August BES Bulletin, so keep an eye out for that.

      It seems a pity that you are having trouble publishing your work. People are getting a bit sniffy about single site studies, but I don’t see why. From the sounds of things it seems like your work is probably fairly novel. From a cynical point of view, just change the word stability for resilience and you’ll have no problems getting published!

      1. Simply that: it was an n=1 + control field experiment. I pointed out that they’d published an n=1 observational study the month before but the editor refused to send it for review saying that “experiments are different”…

      2. But surely n>1 because of replication within your site? Whether n=1 or >1 depends on the focus of the study and how analyses were done, surely?

      3. Sorry for the late reply Philip, I was in Switzerland examining a PhD and purposefully did not take my laptop.

        The study was a whole-site experiment in which we: (1) surveyed the plant-pollinator community; (2) removed all of the flower heads of the most abundant plant; (3) re-surveyed the plant-pollinator community; (4) re-re-surveyed the community after the most abundant plant had re-grown.

        So it was n=1 experiment across the whole site, with replicate sampling within it. We also had an adjacent control site that we surveyed at the same time but did not manipulate.

        It’s the first time such a study has been done and we wanted to see if it was feasible and the possible impact of our flower removal on stability/resilience of the system. The short answer is that the system was very resilient and “bounced back” following re-growth of the plant.

  2. I’ll be following with interest your post on the issue Phil, both due to interest on the term itself, but also on the lack or end to resilience, the so-called tipping points. Also, for the time being, I have to bug you a little bit: I may be dense, but I’d say you did not define it either.

    1. Ha. Good point Mario. From the perspective of the researchers I was working with last week resilience is not one thing and in that sense a simple definition is not really possible. I am of the feeling that it is made up of recovery, resistance and persistence and that you can only really measure it by looking at each of these. Does that make sense to you?

      In some ways it’s a bit like measuring ecosystem services. I can measure carbon storage at a site but unless I also measure a few other services I get a limited view of service provision.

      Also, never feel dense for asking a question. If you didn’t understand something, 9 times out of 10 that is my fault not yours.

      1. It makes sense to me, yes. Like several other terms which are dear to ecologists (community, niche etc.), it refuses to be simple or measurable.

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