Regeneration of potential laurel forest under a native canopy and an exotic canopy, Tenerife (Canary Islands)

Abstract

Exotic tree monocultures adversely affect native ecosystems through competition and through alteration of nutrient availability and dynamics. However, evidence suggests that some tree plantations facilitate a more rapid recovery of native plant communities by providing shelter to the plants below and by attracting seed dispersers. The results are specific to the plantation species and the type of native forest. In this study, we analyzed the differences in regeneration of native woody species in two stands of exotic species, Pinus radiata and Eucalyptus globulus, occupying native laurel forest ground. We also examined the process of regeneration in two adjacent native forest stands to determine whether the exotic plants negatively affect the recovery of the native plant community. The native stands differed from the exotic stands in tree species richness and basal area. However, regeneration was similar in alien and native stands. Differences were quantitatively important, but the species composition of the regenerating community was similar. Moreover, these planted areas recovered their canopy quickly because P. radiata and E. globulus have rapid growth in comparison with native laurel forest species. The rapid recovery of the canopy has prevented more serious erosion damage and has to some extent facilitated the regeneration of native species. The results of this study indicate that a progressive elimination of the exotic stands would favor the establishment and growth of native species. The role of some exotic tree species in the restoration of laurel forest areas should not always be seen as negative.