I heard an interesting discussion on Radio 4 a couple of weeks ago that set me thinking about the theoretical basis of ecological assessment. The discussion, paradoxically, was about education rather than ecology, but I have mentioned in the past that there is common ground between these two disciplines (See “The madness that is “British values”). The discussion involved a comparison of the education systems of the UK and China. In many measures, the education system in China appeared to be outperforming that in the UK, but one contributor questioned whether the measures being compared were actually appropriate. China appeared to perform better than the UK because the measures being used were crude assessments of the proportions of students that passed exams and which, therefore, favoured rote-learning over more interactive approaches to education. The contributor went on to suggest that this search for easily quantified measures of school performance was part of a more general problem. The telling distinction that he used was “making what is measurable important” versus “making what is important measurable”.
That summarises my series of posts from June (see “The human ecosystem of environmental management …” and the two subsequent posts). We have made progress over the last two or three decades towards developing criteria that are “important” rather than just “measurable”. Go back to the early 1990s and being able to demonstrate that the composition of the diatom assemblage was significantly related to the concentration of phosphorus in the water was a step in the right direction but there was little “added value” compared to just measuring the phosphorus concentration (which was a necessary part of the regulation process). During the 2000s we took this a step further, driven by the precepts of the Water Framework Directive (WFD). By the end of the decade we had a good idea of what diatom assemblage could be expected at any river or lake site and use that to measure how far the present state of a site deviated from this ideal. The question that bugged us throughout, though, was how much deviation was acceptable. The problem with an ideal is that it is probably unlikely to be attainable, so we need to infuse our ideals with a spoonful or two of pragmatism (supporters of Jeremy Corbyn, please note …). This is, in fact, at the heart of the WFD, encapsulated in the definition of “good ecological status” (GES). The problem is that GES, itself, is an elusive concept.
The outcome of this is that is has tended to be defined in terms of the “measurable” rather than the “important”. By this I mean that various statistical approaches have been used to determine a point along the index scales that we have developed that we thought met the definition of good ecological status as set out in the WFD. This describes GES as a “slight change” from the community structure associated with the ideal state (“reference conditions”). What has concerned me for some time is that this “slight change” does not necessarily have deep foundations in ecological theory, and does not necessarily guarantee the long-term sustainability of Europe’s waters, the ultimate goal of the WFD. We could argue that a “slight change” leans towards precaution, but the downside is that it is hard to justify the expense of restoration when your argument is littered with “probably” and “maybe”. So where should we look in order to find these deeper foundations?
I came across an interesting new paper that points us in some new directions, if stopping short of giving detailed answers. It focuses on the concept of ecological resilience, defined as “the amount of disturbance that an ecosystem could withstand without changing self-organized processes and structures” (see the reference by Gunderson, below). “Ecological resilience” is no more than preserving the natural homeostasis of a system; just as a healthy human should have the resilience to recover from a minor infection, so an ecosystem should have the capability to recover naturally, without management intervention, from minor natural or anthropogenic perturbations. What this then does is set us some new challenges to understand what we mean by “resilience” in freshwater ecosystems and then to develop some ways of measuring this. I made some suggestions in a post back in January (see “Baffled by the benthos (2)”) and there is scope for other approaches too. These, then, would let us re-examine how we set the limits for GES and, in turn, give us stronger justifications for their restoration. Of course, all this assumes that GES is a steady state that fulfils this definition of possessing “self-organized processes and structures”, but that is the subject for another post …
My own thinking on the ecological theory behind good ecological status is described in:
Kelly, M.G., King, L. & ní Chatháin, B. (2009). The conceptual basis of ecological status assessments using diatoms. Biology and Environment: Proceedings of the Royal Irish Academy 109B: 175-189.
The other two papers I refer to are:
Gunderson, L.H. (2000). Ecological resilience in theory and application. Annual Review of Ecology and Systematics 31: 425-439.
Spears, B.M., Ives, S.C., Angeler, D.G., Allen, C.R., Birk, S., Carvalho, L., Cavers, S., Daunt, F., Morton, R.D., Pocock, M.J.O., Rhodes, G. & Thackeray, S.J. (2015). Effective management of ecological resilience – are we there yet? Journal of Applied Ecology DOI: 10.1111/1365-2664.12497