Pruning stress: Changes in the tree physiology and their effects on the tree health

The pruning of trees produces changes in the partitioning of the reserves. Depending of the time of the, year, the extend and frequency of pruning, some sites of accumulation will disappear and others will be created. Changes in seasonal fluctuations of reserves can appear as well. Pruning also induces a decrease in the quantity of reserves (reduction of crown volume, foliage removal, new sinks) which in the case of heavy pruning can persist several years afterwards. On the contrary it is possible to stimulate the storage of reserves by using the sink-source system under early summer prunings. Pruning like all stresses induces on the one hand a hydrolysis of reserves and on the other hand an accumulation of certain metabolites. Therefore, pruning produces individuals which are physiologically different and whose behavior towards environmental factors or resistance to "pathogens" and predators may also be modified. Manage a tree also means managing its reserves. Thus, by using this approach, one can avoid removing main storage sites, or pruning during periods when the reserves are lowest. One can also stimulate the reconstitution of reserves by summer pruning adapted to the tree.