The growth of multipurpose tree species in the Almeria province of Spain and its relationship to native plant communities.
A series of multipurpose tree species trials were undertaken in SE Spain, to determine suitable species for economic and sustainable land use in a degraded, semi-arid Mediterranean region. From an elimination trial comparing the performance of 21 native and exotic species, 8 (Acacia salicina, A. saligna, A. sclerosperma, Gleditsia triacanthos, Parkinsonia aculeata, Prosopis alba, P. chilensis, Schinus molle) were selected for a growth trial. After 2.5 yr, the highest survival rates were recorded for S. molle (85%), P. alba (76%) and Gleditsia triacanthos (74%), while A. salicina, A. saligna, P. alba and S. molle had the highest growth rates based on height and diameter, suggesting that these 5 species may be useful for semiarid land reclamation in this region. The growth trial site had 4 communities of native (grassland/shrubland) vegetation with differing soil pH and water conductivity. These could be used to indicate the physical and chemical characteristics of soil, topography, local climate and vegetation density of a particular region, to which tree species used for desert reclamation trials respond differently. Thus by assessing the growth rate of multipurpose tree species planted in native vegetation communities, it may be possible to use the native vegetation as indicators to match tree species to specific areas, in order to enhance their growth rate and survival. The 8 tree species used in the growth trial were planted in the 3 plant communities that are common to the region. Tree growth differed between each community; P. alba and G. triacanthos grew equally well in all 3 communities, whereas A. salicina and A. saligna grew better in Helianthinum viscarium [Helianthemum vesicarium]/Linum strictum and Trachynia distachya/Vulpia muralis communities. A Trachynia distachya/Artemisia barrelieri community had the lowest growth of planted trees. These results suggest that the growth of the Acacia spp. can be enhanced by site specific matching using native indicator vegetation.