About Functional Ecology

Countours of functional ecology

The contours of functional ecology, probably more than for other branches of ecology like population ecology, theoretical ecology … need to be discussed due to the various meanings of ‘function’ (Jax 2005) associated with diverse ecological contexts. Functional ecology was originally defined at the organism level (Calow 1987), but many functional processes of organisms (photosynthesis, nutrients use) are also taking place at the ecosystem level and some concepts (e.g. resource use efficiencies) are valid across scales. The function can also be seen as the role played by a system with regards to external beneficiaries (e.g. the role of ecosystem for society, or the role of an organ to the organism fitness). The functions are performed by structures, determined primarily by evolution (organs), man (landscape) or climate (biomes).  These structures are analysed by specific sciences (anatomy, community ecology, landscape ecology, geography) and the study of the functional processes will often draw on the results of, or need the collaboration between, these sciences.  

Definitions of function

The common language definitions of the noun ‘function’ refer to i) an operational process: ‘the way in which something works or operates’ (Cambridge dictionary); ‘any of a group of related actions contributing to a larger action, especially the normal and specific contribution of a bodily part to the economy of a living organism’ (Merriam-Webster) and ii) a goal oriented action: ‘an activity that is natural to or the purpose of a person or thing (Oxford dictionary); ‘the natural purpose (of something) or the duty (of a person)’ (Cambridge dictionary).

Function at the organism level

In biology, a function is ‘the special, normal, proper physiological activity of a body part or an organ’ (http://www.biology-online.org/dictionary/Function). This is an operational process, for example the function of the lungs is to oxygenate the blood. The goal oriented acceptance of function is also used is biology: the function of sugar allocation to nectar is to attract pollinators. It is used in an evolutionary context and refers to the adaptive value of given processes.  Peter Calow (1987) among others refuted the teleological drawback of this acceptance (the purpose of a function is its contribution to the survivorship and fecundity of the organism with that function) and the associated possible Panglossian trap (adaptation is not perfect because evolution lags behind changing environments and is constrained by various mechanisms).

With this evolutionary framework, the successful Functional Biology book series and Functional Ecology journal, both initiated by P. Calow, highly contributed to the spread of the term ‘functional’. These two scientific media are definitely organism orientated. It is about ‘how organisms acquire and then make use of resources in metabolisms, movement, growth, reproduction, and so on’ (Calow 1984). The term function emphasizes i)’process rather than just property ‘, ii) ‘trophic interdependence of the parts and the “role” they play in the economy of the whole’ and iii) the fact that ‘organisms are outcomes of an evolutionary process driven by natural selection’ (Calow 1987).

Function at the ecosystem level

The concept of function, with a similar physiological meaning of processing resources, is also used at the ecosystem level. Photosynthesis, respiration, nutrients acquisition, for example, are functions studied both at the organism and ecosystem level. Some ecosystem functions however (e.g. decomposition), are specific to ecosystem. These functions are the main processes underlying the biogeochemical cycles and often involve many organisms. By analogy with the definition of physiology, ‘the branch of biology that deals with the normal functions of living organisms and their parts’ (Oxford dictionary), the study of these ecosystem functions is also called ‘ecosystem physiology’ (Mooney et al. 1999). Because of the strong interactions between these functions involved in the biogeochemical cycles and the climate, they are also increasingly studied at the earth level.

Functional traits

Facing a high diversity of species, ecologists routinely have lump species together according to similarities in function or in response to abiotic conditions. Recently, functional traits (anatomical and morphological organism’s characteristics that can be easily measured on a large number of species) has been increasingly used to characterize plant species. This approach has been quite successful to describe the plant distribution at the global level, their evolution and dynamics and is being used to improve models predicting future vegetation (Adler et al. 2014, Diaz et al. 2016, Kunstler et al. 2016). This conference also welcomes presentations on functional traits that will explicitly relates these traits to functional processes as described above.

 References

Adler PB et al.  2014. Functional traits explain variation in plant life history strategies. PNAS, 111: 740-745.

Calow P. 1987. Functional Biology Series: Foreword. In: J. Laybourn-Parry A Functional Biology of Free-living Protozoa. Springer Verlag US, 208 p

Calow P. 1987. Towards a definition of functional ecology. Functional Ecology, 1: 57-61

Diaz S. 2016. The global spectrum of plant form and function. Nature, 529: 167–171

Jax K. 2005. Function and ‘functioning’ in ecology: what does it mean? Oikos 111:641-648.

Kunstler G et al. 2016. Plant functional traits have globally consistent effects on competition. Nature, 529: 204–207.

Mooney et al. 1999. Ecosystem physiology responses to global changes. In: B. Walker et al. (eds) The Terrestrial Biosphere and Global Change, Implications for Natural and Managed Ecosystems. Pp. xii+439. Cambridge University Press, Cambridge.