Effect of treeshelters on height, stem diameter and roots
To what extent is improved height an indication of healthy plant growth? How balanced is the growth improvement?
During healthy and balanced growth, a tree will allocate its biomatter to all its organs. It will do so as a response to its environment. Therefore, the key indicators of plant growth are: apical shoot, stem girth, shoots, and roots development.
In the environment of a treeshelter, the tree will adapt and adopt the best strategy for growth and survival. It will therefore react to the microclimate and appropriately change shape and directions of growth.
Fundamental studies have clearly shown that the most effective treeshelter provides an optimal photoactive radiation (PAR) to the seedling and a continuous flow of air through ventilation holes drilled in the bottom of the tube. This study led to the development of the Equilibre Ventex treeshelter.
The effects on height growth, diameter growth, total and above-ground biomass, and roots are shown below.
The ventilation brought by the chimney effect strongly promotes the growth in diameter. More importantly, it maintains an excellent balance between tree height and stem diameter. Not only the girth of the tree is thicker than the control, but its growth is sustained for many years after the tree has emerged from the tube.
Growth results in the field planted Prunus Avium seedlings also show excellent positive results both for elongation and stem diameter. Although the height elongation was similar for both unventilated and ventilated trees, the diameter increase is much improved with Tubex Ventex and starts approaching stem diameters of naturally growing trees.
Considering the total dry biomass of the tree (Prunus avium) at the end of a growing season under irrigation conditions, it is clear that it more than doubled relative to non ventilated treeshelters. The growth in ventilated treeshelters as measured by the total biomass approaches the growth in natural and unsheltered conditions.
By creating an air flow through the shelter driven by a chimney-effect caused by ventilation holes drilled at the bottom, trunk diameter growth has been improved. A recent study showed that the main factor that governs the carbon allocation and regulates the shoot-root balance is actually the mechanical stimuli. In nature, this is created by wind movements.
A 4-year study on the effects of treeshelters on young olive trees showed interesting results on the allocation of matter within the plant. At the end of the first 2 years of field growth in Southern Italy, the dry-matter allocation in the different organs (roots, trunk, branches, shoots, leaves) of the tree grown in green shelters are very similar to those of control.
Dupraz C., Sparrer P.Influence d'abris-serres sur la croissance de merisiers et de noyers cultivés en conteneurs. Doc. Int., 1988, Inra-Lecsa, 29p.
Dupraz Christian, Bergez J.E. Effect of ventilation on growth of Prunus avium seedlings grown in treeshelters. Agricultural and Forest Meteorology 104 (2000) 199–214.
Dupraz C, Coutand Catherine, Jaouen Gaelle, Ploquin Stephane, and Adam Boris
Mechanical Stimuli Regulate the Allocation of Biomass in Trees: Demonstration with Young Prunus avium Trees Annals of Botany, in press.
F. Famiani, P. Proietti, M. Micheli, M. Boco, A. Standardi, F. Ferranti, L. Reale Effects of tree shelters on young olive (Olea europaea) tree growth and physiology New Zealand Journal of Crop and Horticultural Science, 2007, Vol. 35: 303–312.