50 ans d’explorations et d’études botaniques en forêt tropicale

Hallé, F. (2016). 50 ans d’explorations et d’études botaniques en forêt tropicale. Plaissan, Languedoc-Roussillon: MUSEO. p.368.

Cet ouvrage de Francis Hallé offre enfin à chacun la découverte de la diversité de son approche du dessin. Les botanistes connaissent les dessins schématiques très formels des modèles architecturaux, qui ont fait la gloire de Francis et de Roelof Oldeman depuis 1970. 

Dans ces dessins, on reconnaît la position des méristèmes, des feuilles, des fleurs, l’orientation des branches mais pour chacun des modèles, on ne peut reconnaître une espèce d’arbre ni même un quelconque arbre vivant. Et pourtant, chaque botaniste est capable, en observant un jeune arbre vivant, de déduire à quel modèle architectural il se rattache, tel que défini par ces dessins schématiques. C’est là la grande force de ces dessins qui restituent le vivant sous une forme intellectuellement interprétée. C’est utile, nécessaire, souvent beau mais implacablement froid. Mais dans cet ouvrage, nous retrouvons toute la sensibilité de Francis : les arbres ne sont plus des objets exprimant leur devoir génétique mais ils deviennent des objets animés sous lesquels on voudrait se protéger ou dans lesquels un singe sauterait de branche en branche. 

Soudain, l’arbre dessiné devient un arbre vivant, avec tous ses accidents, ses branches cassées, ses réactions opportunistes face à la lumière. Là, dans ses dessins, Francis se libère d’une rigidité dogmatique pour garder sa rigueur scientifique tout en nous immergeant dans la poésie. On retrouve la forêt tropicale et ses arbres, telle qu’elle dut être du temps de l’Eden. Francis aime les arbres, la forêt et les habitants de cette forêt, hommes, oiseaux, insectes, grenouilles, singes… 

Cet ouvrage est un hymne à la plante.”

Patrick Blanc

Forest Components

Oldeman, R.A.A. , Schmidt, P. and Arnolds, E.J.M. (1990)

Foreword

Per 1986, the Dutch Minister of Agriculture and Fisheries approved the five-year financial protection of a research theme ‘conservation and use of forest components’. This system of protected funding was meant to improve the quality of University research, in particular by stimulating researchers in related fields but from different University Departments to work on a common theme of their choice. Existing scientific lines of these researchers were thought to gain plus-value by intensifying contacts with others, by exposing them to discussions yielding new view points, and finally to allow them to adjust their research more closely to a common goal.

All those who know the busy University schedules and the growing restrictions on effective researchtime, i.e.,time not limited to isolated half hours between teaching and meetings, understood that the implementation of these splendid aims of oriented cooperation would cost time and go slowly. One of the ways in which Universities can correct this is the choice of appropriate subjects for graduate studies, and this has been systematically promoted for ‘Forest Components’ since years before the official programme was started.

The group that was responsible for the forest components theme decided to accelerate the process by starting an ambitious project, the writing of a common book. There is no way in which cooperation can be stimulated better, but this way has to be learned and practised too. The result is now before you. The book is not yet ideal in our opinion because it still contains too many traces of the old University tradition of researchers working, each apart, on such narrow subjects as they know best. This way of executing the research of course is necessary to reach sufficient depth. But it carries the risk of loss of vision of the whole system, parts of which are studied. Still a little bit unbalanced, but on its way to improve along lines that are more clear now, this presentation in a pluridisciplinary way is a first step, however, to overcome both the limits of individual researchers and the shallowness of groups.

We trust, however, that it is exactly this wrestling with integration of broad views versus the deepening of restricted views that may be as interesting to the reader as the facts, figures, conclusions and hypotheses on forests and their components which are presented in the following pages. On the brink of the last decennium of this century, it is hoped that this book may find its way to both specialists and generalists, and that most of its contents may also be of significance for the European forest managers.

Dr. ir. R.A.A. Oldeman
Professor of Silviculture & Forest Ecology, Coordinator of the ‘Forest Components’ team.

It is therefore proposed to reserve the notion of ‘pattern’ or in any case ‘architecture’ (Hallé & Oldeman, 1970) of systems to properties that can be directly seen and mapped, being linked to objects occupying a three-dimensional volume. Even if mapping or plotting are automatic, potential visibility by eye is a good criterion to end confusion. Architectural patterns, according to Hallé et al. (1978) are instant pictures. Their change may be indicated as dynamics (Hallé et al., 1978; Fanta, 1986). Dynamics are not processes, if the notion of process is reserved for underlying, organized movements at hierarchical levels deep within the system considered, such as energy and matter processing in photosynthesis or maintenance respiration (cf. Mohren, 1987).

Roelof A.A. Oldeman, p.8

Bibliography

Fanta, J. (ed.) (1986). Forest dynamics research in Western and Central Europe. Wageningen: Pudoc, p.320.

Hallé, F. and Oldeman, R. (1970). Essai sur l’architecture et la dynamique de croissance des arbres tropicaux. Paris: Masson & Cie, p.178.

Hallé, F., Oldeman, R. and Tomlinson P. (1978). Tropical trees and forests: an architectural analysis. Heidelberg: Springer, p.441.

Mohren, G. (1987). Simulation of forest growth, applied to douglas fir stands in The Netherlands. D.Sc. thesis, AUW Theor. Prod. Ecology/Silvic. & For. Ecology, Wageningen, p.183.

Oldeman, R., Schmidt, P. and Arnolds, E. (1990). Forest components. Wageningen: Wageningen Agricultural University Papers, ISSN0169-345X; 90-6, 111 pp. https://edepot.wur.nl/282842.

Five thousand years of sustainablity?

A case study on Gedeo Land use (Southern Ethiopia).

Kippie Kanshie, T. (2002). Five thousand years of sustainability?: a case study on Gedeo land use (Southern Ethiopia). Wageningen, Wageningen University. Promotor(en): R.A.A. Oldeman, E.A. Goewie, P.C. Romeijn. – S.l. : S.n. – ISBN 9789058086457 – 295 pp. https://library.wur.nl/WebQuery/wurpubs/fulltext/198428.

Civitas Naturalis: “A remarkable study, pointing strongly in the direction towards not a rethinking per se but more towards accepting and remembering proven technologies in restructuring our food production, this in the light of the Sustainable Development Goals (SDG 12 Sustainable consumption and production).”

Plate 5.4. An example of a mixed species uneven-aged Gedeo “agroforest” from the lowlands (Tumaata-Cirrachcha area). Note the emergent and majestic Ficus sp. MORACEAE (xillo qilxxa) tree, shading an area of about 0.2ha. Photo by the author (2000),fromtheTumaata-Cirrachchaareaabut 1680masl,alowlandzone. © Kippie Kanshie.

The idea for the present work was initiated in 1993, in the period between February and April, when I was following the MSc course Forest Ecology, delivered by Professor R.A.A. Oldeman, of the Department of Forestry, Wageningen Agricultural University. While following the course, I was pondering upon a would-be subject and almost too late when I came up with the idea of studying the age-old “agroforestry” system of the Gedeo. My supervisor, Ir. van Baren, specializing in Forest Protection, thought that the topic was not her field of expertise and recommended me to Professor R.A.A.Oldeman, who at the time was heading the Silviculture and Forest Ecology Lab.

Gedeo land use incorporates mechanisms, which, as we saw, have indeed enabled them to sustain an average 500 persons/km2 during 5000 years. The basic feature of the Gedeo design is, that yield is maintained at a constant, millenary level, below the maximum yield that could be artificially achieved.

(Kippie Kanshie, 2002, p. 126)

This book presents a case study of an ancient land-use practice that feeds over 450 people/km2 in a mountainous tropical region without terracing, tilling or agrochemical inputs. In this case study of a staple crop ensete, soil fertility and a strong performance in security of production are retained.

The author argues that food and production security are largely safeguarded by maintaining a complex, multi-rotational system with high biodiversity. The crop ensete plays a key-role as a pacemaker species. Its cultivation in different climactic zones and its processing are described.

Conclusions include: ensete, even at the present unimproved state, yields more useful biomass than any other crop plant currently promoted in Ethiopia and that ensete plays a significant role in the maintenance of the production base, deriving from its architecture which helps it to buffer against destabilising factors as well as to accompany other crops so far neglected in research.

This provides the key for sustainability of ensete land use over millennia. Ensete represents a potential solution to the recurring food crises in most parts of the erosion- and drought-prone Ethiopian highlands. Future challenges for donors and policy makers: now the yielding potential of ensete is proven, only cultural barriers remain to its development. This is the challenge to agricultural professionals and also to the international community that want to assist Ethiopia in its efforts towards food security.

Tropical Trees and Forests: An Architectural Analysis

Hallé, F., Oldeman, R. A. A. & Tomlinson, P. B. (1978). Tropical Trees and Forests — An Architectural Analysis. XVII + 441 pages, 111 figs., 10 tables. Berlin‐Heidelberg—New York, Springer‐Verlag. ISBN 3‐540‐08494‐0. https://link.springer.com/book/10.1007/978-3-642-81190-6

Preface: “This book is not an exhaustive survey of known information in the manner of a text-book – the subject is much too big for this to be possible in a relatively concise volume – but presents a point of view. We are concerned ultimately with the analysis of tropical ecosystems, mainly forests, in terms of their constituent units, the individual trees. Many different approaches are possible in the analysis of tropical forests. A simple one is to treat the trees as obstacles which in a military sense intercept projectiles or are a hindrance to foot soldiers (Addor et al., 1970). A similar ap- proach might be adopted by an engineer confronted by a forest which has to be removed to permit road construc- tion. The timber merchant is concerned with the ability of a forest to yield saleable lumber. The interest here is in the size of the larger trunks with some concern for the kinds of trees.

At a less destructive level the scientist aims to comprehend the forest from many different points of view. The forester himself, in conjunction with the taxonomist, will wish to analyze the floristic composition of the forest and perhaps account for species diversity in an evolutionary time scale (e.g., Fedorov, 1966; Ashton, 1969). The evolutionary biologist in his turn may be concerned with reproductive strategies in forest trees (e.g., Bawa, 1974), especially in a comparative way.

The approach adopted by the ecologist offers the greatest scope, since he may combine several different methods of analysis. Much research has gone into the physiognomy of tropical forests, size distribution of trees, stratification, diversity in relation to soil type or soil moisture content and has been summarized recently by Rollet (1974). Phenological studies of tropical forests have produced a great deal of data which reveals the extent to which flower- ing, fruiting and leaf fall mayor may not be seasonal (e.g., Coster, 1923; Holttum, 1940, 1953; cf. also Lieth, 1970). The production ecologist is interested in the forest as an efficient system for light interception and yield of dry matter, both in a relative and a comparative way (e.g., Kira, 1978; Kira et al., 1964, 1969; Monsi et al., 1973; Bernard – Reversat, 1975). Photosynthetic efficiency in terms initially of leaf and branch orientation but ultimately in competitive ability is another stimulating approach which is summarized in the description of trees as “crafty green strategists” (Horn, 1971).

A universal tendency in these approaches is to treat trees as equivalent units – as taxonomic, physiological, reproductive units and so on. Much less attention has been given to the trees in the forest as individuals. This is our approach. However, we do not merely regard trees as individuals at one point in time, but as genetically diverse, developing, changing individuals, which respond in various ways to fluctuations in climate and microclimate, the incidence of insects, fungal and other parasites but particularly to changes in surrounding trees. The tree is then seen as an active, adaptable unit and the forest is made up of a vast number of such units interacting with each other.”

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L’ architecture de la forêt guyanaise

Profile of a patch of forest of about 30 X 40 m in the Saül region, 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. By Oldeman (1974)

Oldeman, R.A.A. (1974a, 2nd ed.). L’architecture de la forêt guyanaise. Mémoires ORSTOM, 73.

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.”

George Mangenot


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).

Forests: Elements of Silvology

Oldeman, R.A.A. (1990). Forests: Elements of Silvology. Berlin Heidelberg: Springer-Verlag.

Silvology is the general science of forest ecosystems, without the usual division between Man and Nature. This systematic treatment of forests intends to integrate and harmonize existing approaches with the help of systems modeling in a hierarchy of close system levels, according to criteria of biological architecture, biomass production and species composition. Scientists and practitioners will appreciate this synoptic treatment of forests and their ecology, allowing the balance of holistic and reductionist viewpoints, and the placement of phenomena and techniques.

Topics covered include: – introduction of the methods, – sections on forest organisms, – a special chapter on trees, – eco-units, i.e. forest ecosystems developing after some zero-event like fire, storm or waterlogging, – silvatic mosaics built by the eco-units of different size, architecture and species composition, – a summary of silvological rules determining system’s behaviour at every level, e.g. fragmentation and fusion, transfer of functions, irreversibility and process oscillation. Read more