Thursday, March 5, 2009

Diversity and function

I had the great fortune yesterday to sit in on part of the Missouri River Recovery Implementation Committee's deliberations, and watch their reaction to the first presentation on Missouri River AM that I have been involved with. The overwhelming impression I had is one of amazing diversity - this is a group of 60+ people from all walks of life and levels of education - they share one thing only, an interest in the people and environments of the Missouri Basin. There are farmers and tug boat captains, scientists, lawyers, and who knows what else. Such a large and diverse group does nothing quickly, but it gives me great hope about the future of the basin and Adaptive Management that such a group now exists.

Not quite serendiptiously I came across a great article on the relationship between biodiversity and ecosystem functioning today - I was following up on a comment by my colleague Ann Bleed that ecologists fail to connect with people, especially when arguing for something vague like "ecosystem function". Patricia Balvanera and colleagues (2006; Ecology Letters 9:1146-1156) conducted a quantitative metaanalysis of studies that perturbed the diversity of a group and measured one or more ecosystem functons. Across a huge range of functions, higher diversity leads to higher function. More recently, Michael Scherer-Lorenzen (2008; Functional Ecology 22:547-555) reported on some elegant experiments demonstrating that functional diversity, rather than species diversity per se, affects decomposition rates. What I liked the most about that work was the use of a quantitative metric for functional diversity based on measurable, ecologically important traits such as specific leaf area and C:N ratios. If all species had the same values of these traits, or if there was a monoculture, then functional diversity is zero. And it worked! What makes this particularly exciting is that it provides a means to connect relative abundances of species, and measurable traits of those species, to variation in ecosystem function. We can use population models to predict changes in relative abundance, and this approach means that we can also show that the mixture of species present can matter.

I find it remarkable how completely random ideas can set up constructive harmonies of thought that lead to new places. As I was wondering about functional diversity in ecosystems, and how to use it as an objective in AM, I received an email from my Dad about David Snowden. Some of the material on that website looked interesting and relevant to my teaching, as well as my work with helping groups develop decision making in ecology. I find his ideas about how groups accrue knowledge and turn it into decisions very intriguing. In one article he describes the idea of scanning information to recognize weak signals, and then act on those signals. Where the resonance happened was when he described how diversity, yeah, diversity of individuals in a group leads to improved scanning of information. Which brought me back to MRRIC, a huge group of diverse individuals. Although that diversity may make life difficult for the scientists that must communicate with them, that same diversity is the groups strength in searching for weak signals, and acting on them.

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