I segreti nella forma

The need for an healthy tree expressing at his best its ecosystem functions is a main theme in the sustainability of an urban environment. The management of the tree shape hasn’t always been sufficiently conjugated with the knowledge of its morpho-physiological development and its peculiar way of building its crown. This lack of knowledge about the tree’s development sequence, often generates an incorrect tree management which instead of fusioning with the tree growing program, works against it creating the base for future problems. The architecture of trees is the science that studies their shape from a morpho-physiological point of view, which expresses the concept that it exists a growth program already written in the genome. This code is defined for every single species and it realizes itself in a sequence of ontogenetic steps. Consequently, the trees’ architecture sums up his structural and physiological complexity and it’s a useful tool for its comprehension. Branching and reiteration are the two processes that allow the construction of the crown from two different perspectives. Firstly, the growing one, which increments the tree in weight and volume. Secondly, the development one, which is characterized by the tree’s meristematic maturity that produces specific structures that identifies different development steps. The branching process allows the construction of the Architectural Unity, which is defined as the maximal expression of an architectural model. The A.U. is a structure with a very high degree of hierarchy. According to this apical control big branches support smaller ones, following a gradual decrease in diameter of the axis supported. the position and the characteristics of the branches follows the architectural model. Reiteration, on the contrary, doesn’t belong to the A.U., doesn’t follow the architectural model and repeats it. It can take different shapes through the branching process (starting from a bud) or the de-differentiation process of an axis, before differentiated in a branch and that individualizes and leaves the model. A big theoretical distinction has to be made between the sequential reiteration, that express itself inside the crown development sequence and it’s integrated in the tree organization, and the deferred reiteration, that generates “late” structures not included in the development sequence. With the sequential reiteration ,the reiterated A.U. in the crown are integrated in the development sequence of the tree and, fork after fork, they suffer a decrease in dimensions , in growing rate and in number of axis categories as the number of A.U. increase. The architectural diagnosis is an approaching method used to read and interpret, through the study of the supporting structure, of the branching and their distribution and hierarchy, the tree development step and its potentiality for its future growing, obtaining important pieces of information about his future management. Indeed, as far as our comprehension on tree goes so far, the intervention techniques have to modulate and adapt depending on the tree’s age, to its energetic level, to its capacity to recover from the spiral of decline. The principle to follow in order to diagnose the physiological phase in which the tree is, is to realize two series of observations. The first concerns the decay symptoms of the crown (foliar rarefaction, poor branching, dead structures…) and the second concerns the crown restoration processes (development of substitutes, their morphology and orientation,…). The study of the strong relationship between this two antagonist processes, allow us to identify the phase in which the tree is. The possible applications of an architectural diagnosis and more in general of a deeper knowledge of the arboreal architecture , are many. The application of the Architectural Analysis can, at the beginning, might be taught to whom has just approached this matter. As a matter of fact, we need to study the basic principles to predict the development sequence of every single species as well as a lot of time and perseverance. Indeed, because the great variability of the vegetal world, the A.A. makes us doubt what we know about it. On the other hand, besides the initial difficulties of this approach the chance we have of learning directly from the silent language of trees what is the best for them in order to propose an acceptable coexistence with mutual benefits in invaluable.

Strumenti strategici per interpretare le dinamiche di crescita di una determinata specie e gli stadi di sviluppo di un singolo esemplare, l’analisi e la diagnostica architetturale si rivelano di grande utilità per la messa a punto di piani gestionali basati sulle reali esigenze dell’albero.