Effects of site preparation with micro-basins on Pinus halepensis Mill. afforestations in a semiarid ombroclimate

Abstract

A forested area at the Sierra de Gador, Almería, Spain, was afforested with Aleppo pine (Pinus halepensis Mill.) 13 years ago using a technique never before used in Europe for forested areas: banks with micro-basins. This technique is compared in our study to the banks without micro-basins, both in sunny and shady slopes. It is also analysed whether this site preparation modifies the specific composition of the pre-existing vegetation. The average height of the pines planted on shady plots with micro-basins is 3.06 m whereas in shady plots without micro-basins the average height is 2.37 m, in sunny slope average height are 2.52 m compared to 1.61 m with and without micro-basins. These differences are significant, as are the ones in diameter: 11.1 cm compared to 8.5 cm in the first case and 11.0 compared to 7.0 cm in the second. Micro-basins supply possibly enough water to the banks so that the annual increase of the growth rings does not depend on the rainfall, not even during a particularly dry year. In plots without micro-basins there is a close relationship between the annual trunk growth and the spring rainfall. Using a multivariate analysis it is shown that neither land removal or a change in the hydric accumulations affect the composition of the pre-existing vegetation. © INRA, EDP Sciences, 2006.