Profile of a patch of forest of about 30 X 40 m in the Saül region by Roelof Oldeman (1974), at an altitude of 285 m. Thick line: trees of the whole of the present; dotted and shaded: trees of the future set; thin line: standing or fallen trees from the past as a whole; thick dotted line: trees outside the plot. Structural sets at about 15 m, 40 m and 55 m.
Cet ouvrage a fait l’objet d’une thèse soutenue le 16 décembre 1972 à l’Université des Sciences et Techniques du Languedoc pour obtenir le grade de Docteur ès Sciences Naturelles, with highest honours (summa cum laude).
“The book concludes with an attempt to interpret forest profiles drawn, by some of its predecessors, in various tropical or extratropical regions. Most of all, I found from this essay the inadequacy of the profiles in question, no doubt excellent at the time they were sketched, but incomparably less accurate and less representative than those of Oldeman…
…The main thing in Oldeman’s work is that he created a methodology made up of a whole set of perfectly articulated morphogenetic, ecological and physiological concepts allowing the structural analysis of the populations of trees, mostly dicots, in all regions of the world. A recent, unpublished essay by the author on a Massachusetts forest showed that it is possible, by the methods tried in Guyana, to explain it and to understand the profound differences distinguishing it from equatorial forests. The flexible and adaptable character of the oldemanian system is thus highlighted. This work, which testifies to a very imaginative and creative spirit, is called to a great resonance.”
Oldeman summarises on p.78:
“The forest is characterized by its trees. In the first part, we examined the rules to which tree growth obeys, expressed in an architecture peculiar to each species, but whose principle can be identified in relation to some twenty tree models. These criteria make it possible to distinguish three sets of forest trees. The whole of the future includes young trees, who, conforming to the initial model, often regenerated, will give structure to the future forest. The whole of the present brings together the trees having reached, by an abundant reiteration and growth in thickness, their maximum biomass and which determine the current architecture of the forest; the whole present is subdivided into structural sets at different heights. Forest architecture is stratified; the relative density of the trees in each set determines the good or bad visibility of “strata.” Lastly, the whole of the past includes trees in the process of being eliminated, traces of previous structures more or less blurring the architecture of the present…
… A fourth forest complex is clearly visible in the windfall. It brings together the seeds and active meristems, in contrast with forest layers where these organs are mostly latent. It is worth remembering that seeds and active meristems are the exclusive producers of forest biomass; they form the entire infrastructure of the forest.”
Oldeman on p.81:
“The survey of a profile and a plan of a forest plot in the described biotope was carried out without taking into account the undergrowth, in a layer less than ten meters, because we are studying the framework of the architecture forestry. This is why the parcel was chosen in a place where the undergrowth had been recently removed for the entomological mission. The area of the plot was approximately 30 X 40 meters, more than sufficient for an architectural study of the forest, the structural continuity of which outside the plot was easy to verify by direct observation. It goes without saying that this method cannot be applied during an inventory targeting another aspect of the forest, such as phytosociology, floristics or forest size.
The plot plan was established by locating the topographical position of the trunks of all the trees and estimating the extent of the projection of their tops on the ground. The diameters of the trunks and the dimensions of any buttresses were measured at the same time and entered on the blank. The heights – total height, free trunk – were then determined using a Blume-Leiss dendrometer. Finally, sketches of the architecture of each tree were made in the field; their perspective deformations were corrected, using height measurements, on the final profile).”
Bibliography
Oldeman, R.A.A. (1974a, 2nd ed.). L’architecture de la forêt guyanaise. Mémoires ORSTOM, 73.