Functional Groups in Wetland and Riparian Plants: A Strategic Perspective

In this short, 15-minute talk Paul reviews the difference between functional and phylogenetic classification of plants, and provides a set of published examples that illustrate the importance of functional classifications for ecological prediction. It begins with an introduction by David Merritt.

Phylogeny and function: two different ways of looking at plants

Wetland and riparian plants, like all living organisms, can be classified in two entirely different ways. The first system is phylogenetic, which began with Linnaeus (and flower morphology) and continues with the Angiosperm Phylogeny Group (and DNA sequences). This is a powerful way to retrace the origins and evolution of plants, but is rather useless for ecological prediction. The second system is functional. In the broad sense, it is almost the opposite of the phylogenetic approach, because we are instead seeking patterns in evolutionary convergence.

For predictive ecology, we need to identify these convergent groups, come up with consistent names for them, identify their key life history traits, and incorporate them into predictive models. It is not a new idea: foundations include Humboldt (19 groups), Raunkiaer (12 groups), Hutchinson (26 groups, just for aquatics), van der Valk (12 groups) and Grime (3 groups). All of these influenced my own team’s approach to this problem and our body of work included mass screening for ecological traits such as relative growth rate and relative competitive ability. The path ahead remains clear. We need to compile a matrix of ecological traits that transcends morphology, adding in innovative functional traits for which we must screen systematically: relative growth rate, nutrient conservation, relative competitive ability, juvenile (establishment) traits, and no doubt others. We are nearly there. 

The topic of functional classification and its role in predictive ecology of wetlands is described in more detail in Chapter 13 of Wetland Ecology: Principles and Conservation, Section 12.6

The important distinction between functional and phylogenetic classifications in ecology is covered in Chapter 2 of Plants and Vegetation.

More about the symposium

Floodplains around the world are changing as humans modify spring flood regimes by constructing dams and reservoirs. This 2015 symposium explored how we can predict the effects of such changes by focussing upon the life history traits of plants that live in floodplains. The symposium was organized by Daniel Sarr and David Merritt.