From the universe as a whole down to the atoms: distinctions between community and ecosystem ecology

Tools of the trade: ecosystem ecology

In one of the more nerve-wracking moments of my early career I was informed that the ecosystem concept was “putting food on the family table.”  I was to stick to the methods of ecosystem ecology and not to waste time with community level questions.  By this I understood that I should not indulge an interest in individual organisms nor attempt to identify these to the species level – certainly this was consuming a lot of my time. I should not, I was told, become overly interested in species diversity, another community-level phenomenon.  Though ecology is rapidly changing, nevertheless as recently as a decade and a half ago you picked your favourite flavour early – if you chose chocolate it is frowned on if you started adding dollops of vanilla.

The ecosystem, as we have discussed, is a compound constituted by all the organisms of a region interacting with the non-living environment – soil, water, and atmosphere.  In modern ecology the ecosystem concept has become the foundation for functional studies of the environment, often at the landscape scale, where ecologists study the processes contributing to the flow of energy (primarily starting with the photosynthetic “fixing” of the sun’s energy by plants) and the cycling of nutrients.  For instance, a present-day ecosystem ecologist might be interested in how the rates of leaf litter decomposition in a woodland affects the availability of nutrients in the soil, thus influencing subsequent plant growth.  This functional interpretation of the ecosystem is contrasted with the approach taken by population and community ecologists who study the interaction of individual organisms, the growth of populations and the interactions that occur between individual of multiple species coexisting in the same place at the same time. 

Is your climax a super-organism? The complexity of nature. Or, on being made of little parts

Vegetation Climax, Western Ghats 2009

ECOLOGICAL PAPERS WRITTEN IN THE 1930S are the Burgess Shale of the discipline. As in that middle-Cambrian fossil bed of primordial forms, everything is already there and often piled pretty closely together. Arthur Tansley’s 1935 paper “The use and abuse of vegetation concepts and terms” appeared in the journal Ecology and re-reading it three-quarters of a century later opens a window on the debates in the early years of discipline. Tansley’s proximate concern is to chastise the younger South African ecologist John Phillips, whose views on vegetation development had chagrined him. In the background is the powerful figure of Frederic Clements, the senior American ecologist and archdeacon of the concepts of “succession” and the “complex organism”, whose views Phillips was advocating and justifying. These days Tansley’s paper is primarily remembered for introducing the term “ecosystem”; however, other debates swirl around it, including questions concerning the degree to which we might regard the largest entities of nature as “super-organisms”.  (For an account of this paper go here) Is the plant community correctly seen as a large independent organism that grows, matures, and reproduces in the way an individual plant or animal does? Debates about this matter – a storm in arcane scientific teacup – prefigure more contemporary debates about Gaia: can the planet itself be regarded as a single super-organism? 

What was eating at Sir Arthur G. Tansley? On the occasion of 76th anniversary of the ecosystem concept

Remembering the late Frank Golley who wrote about it.

This month is the 76th anniversary of the naming of the ecosystem concept. The paper in which the term first appeared is entitled, appropriately enough, “The use and abuse of vegetation concepts and terms”, (the ecosystem being offered, naturally enough, as a useful one) and appeared in Ecology, the flagship journal of the Ecological Society of America, in July 1935 . In it, the British ecologist Sir Arthur George Tansley takes a scythe to the conceptual crop that the infant discipline of ecology had produced since the early years of the 20th Century. He separated the terminological wheat from the chaff. The task was not, of course, simply to determine which were the more delicious ecological terms; ecologists have always loved their terminology: climax communities, subclimaxes, proclimax, seres, plagioseres, prisere, succession and so forth; little of it is euphonious. Rather, he determined the utility of terminology based upon his perception of the “naturalness” of the units of nature they entail. Terms are abused when they promote analogies which do not produce fruitful empirical research programs. Terms are also abused, as Tansley hinted, when they smuggle in a set of metaphysical assumptions (e.g. “an imagined future whole” to be realized in an ideal human society); assumptions Tansley believed had no business in the dispassionate contemplation of nature. Especially when ecology was struggling to assume a position among the other natural sciences it seemed not the time for the discipline to divert on philosophical tangents .