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Portrait of Pierre Dansereau 1911-2011

Pierre Dansereau 1911 - 2011

Looking once more at my dial which I have centered upon the individual, it strikes me that there are any number of unfinished tasks that can be done only by ourselves, by ecologists ...

We really come into our own in the study of population, community, ecosystem, bioclimate, and living organisms. It is at these higher levels that the drama of natural selection is being played and that all the forces of the environment combine in peculiar, dynamic patterns of resource-circulation that we are uniquely competent to apprehend.

I do think that "ecosystem ecology" is the ecology of the future. It promises altogether as much as molecular biology to provide us with the famous "unifying principles".

Let us suppose that you and I stop for a moment to look at three stands of vegetation: a redwood forest, an Iowan prairie, and a cabbage field.

   1) Consider the question of biomass. The cubic dimensions of the forest are enormous. Although its roots do not extend to a great depth, the total space occupied by the living plants is very great in comparison to the deeply-rooted prairie and the surface-skimming field ...

   2) Consider the question of rhythm. The redwoods and most of their association are evergreen. They function all year, although with a seasonal low. The prairie has a long dormant period, a dynamic early grass-dominated season, followed by a season during which much maturation of fruit takes place. The cabbage-field of course, is strictly annual, its activity covering something less than the potential growing season.

   3) Consider the question of storage. The ratio of active to stored materials in the biomass of the redwood forest is many times that of the prairie where almost all that is taken in by the living plant is cycled back to the air and soil within the year. As for the cabbage, it is a sheer exploiter ...

   4) Consider the question of composition. How did the species that grow together in these three communities get where they are, through what migrations, survivals, and adjustments? The cabbage, for example, is a seacoast biennial ... artificially selected and introduced.

  5) Consider the sharing of resources. The cabbage is dispensed from any sharing. The resources which it needs are deliberately provided. The prairie with its different depths of roots and different flowering periods for the grasses vs. other herbs and the very few low shrubs has at least three tapping mechanisms. The variety of life forms ... is even more evident in the redwood forest ranging from very tall, very long-lived, mostly vegetatively propagating trees to smaller, shorter-cycled, seed-propagating trees and shrubs to deeply buried bulbs and buds of somewhat ephemeral growth to lush evergreen tall herbs ...

Consider also ... but I have rambled enough and will not try to give this casual contemplation of sites the symmetry of a blueprint for the future of ecological research. Let me conclude by saying that I think we too are on the threshold of a new era in which we shall have to redefine our terms and our task ...

No, my dear ecologists, our task is not done 

Quelques raisons d'espérer ... un film sur l'oeuvre et la vie de Pierre Dansereau (french version only)

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