Toward Contemporary Arboriculture

Man is a pattern-seeking animal. For millennia, many cultures have given a special significance to the number seven. 7 sets the mark for completeness in life cycles as in 7 days a week. William Shakespeare attributed 7 stages to the human life cycle. The early twentieth century philosopher Rudolf Steiner attributed seven-year cycles to human development. Robert Fripp, the avant-garde guitarist extraordinaire, teacher and thinker, has always referred to his on-going life projects in terms of seven-year life cycles.

If we consider these seven-year cycles or hepta-cycles, Modern Arboriculture starts its first hepta-cycle of seven years in 1977 with the publication of the CODIT model by Alex L. Shigo and Harold G. Marx.

Shigo, A. L. and Marx, H. G., 1977. Compartmentalization of Decay in Trees (N. 405). Department of Agriculture, Forest Service.

1977 also marks the beginning of a new era in tree architecture with the introduction of the architectural unit concept by Claude Édelin from his first doctoral thesis. The concept led to a more detailed qualitative architectural analysis of trees and opened the doors to an essential line of botanists-researchers directed by Édelin, pioneers in the application of tree architecture in arboriculture.

Édelin, C., 1977. Images de l’architecture des conifères. Thèse, Université des Sciences et Techniques du Languedoc, Montpellier.

7 also sets the mark for perfection as in 7 pure tones in the diatonic scale, 7 colors of the rainbow, 7 continents, 7 seas (oceanic bodies of water), 7 wonders, 7 deadly sins, etc. There are seven basic units in the metric system from which all other units are derived. In western culture, 7 chakras (centers) are attributed to the human body. There are 7 hierarchical levels in Linnaean taxonomy. The atom in nitrogen, an essential element for all forms of life on the planet, has a central nucleus composed of 7 protons and 7 neutrons surrounded by 7 electrons. George Ivanovich Gurdjieff, one of the most influential teachers of the twentieth century, referred to the law of seven (Heptaparaparshinokh) as a universal law.

Modern Arboriculture enters its second hepta-cycle in 1984, 7 years after the publication of the CODIT model by Shigo and Marx. 1984 sets the mark for the application of the CODIT model in arboriculture with the publication of the Natural Target Pruning model, marking the demise of flush cuts. 

Shigo, A. L., 1984. Homeowner's Guide for Beautiful, Safe, and Healthy Trees (Vol. 58). US Department of Agriculture, Forest Service, Northeastern Forest Experiment Station.

1984 also marks the end of arboreal surgery in western culture, following Alex Shigo's legendary conference in Heidelberg, Germany. 

The third hepta-cycle begins with the publication of "Modern Arboriculture" 7 years later in 1991. 

Shigo, A. L., 1991. Modern Arboriculture: A Systems Approach to the Care of Trees and Their Associates. Shigo and Trees, Associates.

This 3d hepta-cycle took arboriculture to unprecedented heights. Shigo's publication set a definite mark in this modern period, raising the level of awareness in the community. Also, the VTA-Method (Visual Tree Assessment) introduced by Claus Mattheck and Helge Breloer set the standards in tree risk assessment giving rise to today's constantly evolving QTRA, TRAQ and VALID methods, followed by their culminating collaboration "The Body Language of Trees".

Mattheck, C. and Breloer, H., 1992. Feldanleitung fur Baumkontrolen mit VTA, Landschaftarchitektur, 6. 

Mattheck, C. und Breloer, H., 1993. Handbuch der schadenskunde von bäumen–der baumbruch in mechanik und rechtsprechung. Freiburg: Rombach Verlag.

Mattheck, C. and Breloer, H., 1994. Field guide for visual tree assessment (VTA). Arboricultural Journal, 18(1), pp.1-23. 

Mattheck, C. and Breloer, H., 1994. The body language of trees: a handbook for failure analysis. HMSO Publications Centre.

This whole cycle is also marked with a doctoral theses boom from the pioneers of the application of tree architecture in arboriculture, including Claire Atger, Christophe Drénou, Pascal Genoyer and Jeanne Millet; all theses directed by Claude Édelin. In the years to come, Édelin's scholars would transpose the scientific theory in a comprehensible-accessible language available to the arboriculture community. 

Atger, C., 1992. Essai sur l'architecture racinaire des arbres. Thèse de doctorat, Université de Montpellier II, Montpellier.

Drénou, C., 1994. Approche architecturale de la sénescence des arbres. Le cas de quelques angiospermes tempérées et boréales. Thèse de doctorat, Université de Montpellier II, Montpellier.

Genoyer, P., 1994. Contribution à l’étude de la régénération d’arbres traumatisés. Thèse de doctorat, Université de Montpellier II, Montpellier.

Millet, J., 1997. Rapports entre le mode de développement architectural des arbres et le statut successionnel des espèces dans le Québec méridional. Thèse de doctorat, Université de Montréal, Montréal.

The 4th hepta-cycle in Modern Arboriculture is marked 7 years later in 1998 with the publication of the Hamburg Tree Pruning System by Dirk Dujesiefken and Horst Stobbe, the most rigorous pruning research available to date. The following year, the still unparalleled to this date tree pruning handbook, "La taille des arbres d'ornement" ("The pruning of ornamental trees") by Christophe Drénou was published, quickly establishing itself as a reference on the field (also translated in Spanish) presenting reasoned pruning criteria beyond the usual know-how from common pruning guides.

Stobbe, H., Dujesiefken, D. & Kleist, G., 1998. Die Hamburger Schnittmethode – Grundlagen und neue Erkenntnisse. In: Jahrbuch der Baumpflege 1998 (eds D. Dujesiefken & P. Kockerbeck): 184-193. Thalacker Medien, Braunschweig.

Dujesiefken, D. and Stobbe, H., 2002. The Hamburg Tree Pruning System–A framework for pruning of individual trees. Urban Forestry & Urban Greening, 1(2), pp.75-82.

Drenou, C., 1999. La taille des arbres d'ornement: du pourquoi au comment. Institut pour le développement forestier.

Drénou, C., 2000. La poda de los árboles ornamentales. Mundi-Prensa Libros.

The end of the 4th cycle is marked with a boom in environmental arboriculture originated by ecologists in the UK and the introduction of coronet cuts by Neville Fay in 2003, which the rest of the world is still catching up, almost 20 years later.

Fay, N., 2003. Natural fracture pruning techniques and coronet cuts. Treework Environmental Practice.

The beginning of the 5th hepta-cycle is dominated by the application of tree roots and soil science in arboriculture, unveiling the hidden face of trees to the community. In 2006 the most advanced handbook on tree roots to date is made available, edited by Christophe Drénou. The “Tree Roots: Form and Function” project in the UK is materialized by publishing “Tree Roots in the Built Environment”, 2006, setting new standards in soil assessment and designing spaces for trees, followed by “Up by Roots” by James Urban, 2008.

Drénou, C., 2006. Les racines : face cachée des arbres. Forêt privée française.

Roberts, J., Jackson, N. and Smith, M., 2006. Tree Roots in the Built Environment. Crown Copyright, The Stationary Office, Norwich, England. 488 pp.

Urban, J., 2008. Up By Roots: Healthy soils and trees in the built environment. International Society of Arboriculture.

The completion of the 5th hepta-cycle in modern arboriculture is marked by 3 major events: (1) The publication of a new model of branch attachment by Duncan Slater and Claire Harbinson, 2010, bringing light to a long-term incorrect and misleading hypothesis of branch-to-stem attachment; (2) the publication of the CODIT principle, 2008, 2010, by Dirk Dujesiefken and Walter Liese, acknowledging four phases of reaction to wounds and modifying the “D” of Decay in CODIT for Damage, comprising Desiccation, Disfunction and Decay; (3) the end of the cycle is also marked by the introduction of the revolutionary ARCHI method in 2011. A practical approach based on tree architecture for diagnosis and intervention introduced by Christophe Drénou et al.

Slater, D. and Harbinson, C., 2010. Towards a New Model of Branch Attachment. Arboricultural Journal, 33(2), pp.95-105

Dujesiefken, D. and Liese, W., 2008. Das CODIT-Prinzip: von den Bäumen lernen für eine fachgerechte Baumpflege. Haymarket Media.

Dujesiefken, D. and Liese, W., 2010. The CODIT Principle: The Defence Reactions of Trees After Wounding. Acta horticulturae et regiotecturae, special issue Nitra, Slovaca Universitas Agriculturae Nitriae, 2010, s. 1-4

Drénou, C., Bouvier, M. and Lemaire, J., 2011. La méthode de diagnostic ARCHI. Application aux chênes pédonculés dépérissants. Forêt entreprise, (200), pp.4-15.

2012 marks the beginning of the 6th hepta-cycle with the publication of Jeanne Millet's compendium for tree architecture in temperate zones, making accessible a humongous body of scientific research in tree architecture to the arboriculture community.

Millet, J., 2012. L’architecture des arbres des régions tempérées: son histoire, ses concepts, ses usages. Éditions Multimondes.

The end of the 6th cycle is marked by the publication by Duncan Slater of the association of natural braces and the development of bark-included forks, unveiling a large share of their mystery.

Slater, D., 2018. The association between natural braces and the development of bark-included junctions in trees. Arboricultural Journal, 40(1), pp.16-38.

Slater, D., 2018. Natural bracing in trees: Management recommendations. Arboricultural Journal, 40(2), pp.106-133.

We are living the 7th and final hepta-cycle of Modern Arboriculture. Already marked from its beginnings by the collaboration between Duncan Slater and Christophe Drénou, demystifying a long-term misleading perception of tree forks. Their collaboration showcases recent interdisciplinary approaches comprising tree architecture, biomechanics and mechanobiology to embrace a new perspective on tree forks in arboriculture.

The beginning of this last hepta-cycle is also marked by Duncan Slater’s publication of the mechanical effects of bulges in bark-included forks, bringing light to yet another long-term incorrect and misleading hypothesis. It is also marked by the publication of Christophe Drénou's entirely revamped and revised tree pruning handbook, unveiling 10 years of evolution of the ARCHI method in detail and proposing non-pruning as a legitimate tree management option.

Drénou, C., Restrepo, D. and Slater, D., 2020. Demystifying tree forks: vices and virtues of forks in arboriculture. Journal of Botany Research, 3(1), pp.100-113.

Slater, D., 2021. The mechanical effects of bulges developed around bark-included branch junctions of hazel (Corylus avellana L.) and other trees. Trees, 35(2), pp.513-526.

Drénou, C., 2021. La taille des arbres d'ornement, 2e édition: Architecture–Anatomie–Techniques. CNPF-IDF.

2025 will be marking the end of an era in arboriculture known as Modern Arboriculture (7 hepta-cycles, roughly half a century) and we will be entering Contemporary Arboriculture in 2026... that is, if we consider life 7-year cycles. 

David S.Restrepo v.1.5.1-2021.10.19