Effect of shelter tubes on establishment and growth of Juniperus thurifera L. (Cupressaceae) seedlings in Mediterranean semi-arid environment

This paper evaluates the growth and survival of Juniperus thurifera L. seedlings planted using or not the shelter tube Tubex (R) in Mediterranean semi- arid agricultural lands (S. E. Spain). Biometrical data were recorded on the plants in the field during two years and several seedlings were extracted by random at the end in order to measure additional morphological parameters related to root system. Micrometeorological measurements were collected on the experimental site to characterize the microclimate induced by the treeshelters. A survival level of 100% was registered inside and outside the shelter. However, an increment of absolute maximum temperature and an important reduction of radiation detected inside the shelter, could make the plants grow higher and to increase their foliage surface with a significant negative effect upon the root biomass, quantity of fine and thick roots, length of the main root and root collar diameter, which constitute the key for its survival in climates in which hydric resources are scarce and the plants are subjected to long periods of xericity. Therefore, the use of the shelter tubes seems inadvisable, at least in these environments and for species with these characteristics.