Effective protection of young broad-leaved seedlings against domestic and wild animals may be achieved either by fencing the stand or by protecting every single tree with a shelter. Fencing is a definite non agroforestry practice, as it implies the loss of the potentially grazed intercrops on the plot. It may also generate conflicts between foresters and breeders that may endanger the young plantation. Protecting each tree is perfectly suited for agroforestry systems, as it allows an intensive management of the intercrop, including direct grazing or contact herbicides application. Therefore, this practice has gained a wide acceptance throughout Europe during the last decade. However, strong concerns about tree growth in treeshelters have been raised : tree growth may not be satisfactory with weak rooting systems and poor tree stability. In some agroforestry experiments, shelters were removed and replaced by nets in order to help them recover a more satisfactory growth pattern. This concern was even stronger when tall shelters were compulsory, as for protection against cattle (2.5 m tall shelters). We show that a proper ventilation of the shelter may reduce most of the drawbacks of tree shelters. This ventilation is achieved with an aperture at the bottom of the shelter, creating a chimney effect depending on the direct sun beam. The tree is correctly supplied with carbon dioxide, alleviating the main limiting factor of photosynthesis inside treeshelters under temperate areas. With such ventilated shelters, higher light transmission further improves tree growth, and is obtained with new light green pigments in the shelter material. Concurrently, the increase in temperature inside the shelter is limited, and the tree water use efficiency is improved. These new treeshelters improved the diameter growth of the trees by 40% compared to conventional shelters, and may be used for both silvopastoral systems (protection against livestock) and silvoarable systems (localisation of the trees for the mechanised operations on the intercrops, use of contact herbicides).