What do ecological systems “do”? A little history, and 2 quick case studies. Start 230 yr ago, with Adam Smith’s Invisible Hand:.
What do ecological systems “do”?
A little history, and 2 quick case studies
Start 230 yr ago, with Adam Smith’s Invisible Hand:
"Every individual is continually exerting himself to find out the most advantageous employment of whatever capital he can command. It is his own advantage, indeed, and not that of the society, which he has in view. But the study of his own advantage naturally, or rather necessarily leads him to prefer that employment which is most advantageous to society."
“…and he is in this, as in many other cases, led by an invisible hand to promote an end which was no part of his intention.”
And from Adam Smith, via Thomas Malthus to Charles Darwin:
"In October 1838, that is fifteen months after I had begun my systematic enquiry, I happened to read for amusement Malthus' Population, and being well prepared to appreciate the struggle for existence [a phrase used by Malthus] which everywhere goes on from long-continued observation of animals and plants, it at once struck me that under these circumstances favourable variations would tend to be preserved and unfavourable ones to be destroyed. The result of this would be a new species. Here then I had at last got hold of a theory by which to work."
“Favorable variation” = ability to degrade gradients?
Side trip into chemistry and physics:
Sadi Carnot, a French military engineer, is credited with the first thinking about the second law of thermodynamics: energy is always lost or wasted; efficiency of energy transfer is always < 100%.
Rudolf Clausius, a German professor, emphasized you can’t get work out of a flow of energy unless the energy has somewhere to flow – with no “downhill,” you can’t harness energy. The “wasted” energy he called “entropy”: S = Heat (J)/temperature (oK)
Ludwig Boltzmann, an Austrian professor, linked entropy to probability 100 yr ago – how many ways can you rearrange a set of objects, and how likely is any given arrangement?
S = kB x ln(W)
Entropy = Boltzmann’s constant times the log of the number of possible arrangements
50 years later, Claude Shannon worked with communication and information, and described:
Information = -K x ln(p) where p is the probability of a particular arrangement.
Apparently the idea of ‘order’ is no longer welcomed by physicists and chemists as a domain of entropy? A topic for another free lunch…
Getting back on the “thread” of ecology and what ecosystems “do”:
Ideas about vitalism, life forces ruled biology (began to fade after Darwin).
Frederic Clements crystalized (cemented!) the Superorganism view of the 1910s, 1920s, 1930s (but what did these superorganisms “do”?
Boltzman in 1905: “the struggle for existence is a struggle for free energy to do work.”
Lotka in 1922: life prevails and persists when it maximizes the flow of useful energy (= power)
1925, Ludwig von Bertalanffy emphasized that:
Ontogeny and behavior of organisms
cannot be summed up from cells
But no evidence of vitalism -- so what gives?
Open systems and “General Systems Theory”
(Adam Smith’s “invisible hand” has reappeared)
Biology in the 1930s had no math
(in 1942, G.E. Hutchinson noted that Lindemann’s classic trophic paper “for the first time… a form amenable to productive abstract analysis.”)
General Systems Theory: “(tries) to derive concepts characteristic of organized wholes... such as interaction, sum, mechanization, centralization, competition, finality….and apply them to concrete phenomena.” (LvB)
Open systems reduce entropy within their “local” systems, but maximize entropy production of the “global” system.
So what does this “view” lead to? A Nobel Prize for Ilya Prigogine in 1977 for work done in the 1940s!
Linear differential equations are at the heart of classical thermodynamics; Prigogine was interested in situations held far from equilibrium, where things are non-linear… but not random. “Dissipative structures” are elaborate, low-entropy systems that generate great amounts of entropy.
Cool stuff? A physicist noted in Scientific American (May 1995, From Complexity to Perplexity) “I don't know of a single phenomenon his theory has explained.”
At an ecosystem scale, where does this lead?
H.T. Odum popularized the “Maximum Power Principle”:
Ecosystem tend toward a state of maximum throughput of useful energy
Which sounds like Prigogine’s “dissipative structures” at work;
Which sounds like maximum degradation of gradients;
Which sounds like maximum entropy production.
“Open systems obey the 2nd Law globally by working against it locally.”
Case 1. Dave Tilman’s Resource Ratio model: the “winner” in competition among plants is the species that survives once available resources (gradients) have been pulled below the survival threshold of the other species.
pine survival threshold
Changes in ecosystems over time (without major disturbance) should lead to what?
Early successional ecosystems should:
Leave a large part of the incoming
solar energy unaltered (undissipated) -- reflected, or re-emitted as low-gradient infrared radiation from hot soil to the air.
Older ecosystems should:
Process more energy, turning concentrated solar radiation into dispersed water vapor in the air,
and re-emitted energy as low quality
Case 2. A comparison of the radiation budgets for 4 “ecosystems” in Oregon (from an ultralight plane)
Quarry: no life
Clearcut: low-stature plants, low leaf area
23-yr forest: taller, more leaf area
400-yr forest: even taller, more vertical
variety in structure, leaf area
Where’s the greater entropy production?
Tree invasion of prairie or tundra
Alien plant invasion
Alien “consumer” invasion
Impact of fire regime on entropy production
Hours, years, centuries?
Where will Adam Smith’s invisible hand appear next?