Recruitment responses of shade‐tolerant and heliophilous trees in degraded areas: The necessity of knowing the recruitment autecology of species for effective reforestation decisions

Abstract

AbstractDirect seeding is a reforestation technique that allows introducing a great variety of tree species in degraded areas with less logistics, but tree establishment rates are usually low because developing plants do not tolerate the high sun exposure, extreme temperatures, and low soil moisture that prevail in these habitats. This leads to the proposal that seeds should be planted beneath shrubs or herbaceous plants that ameliorate harsh abiotic conditions, although this can also trigger interspecific competition and impair the performance of developing trees. This study aimed to test these proposals in dry forests in northwest Argentina. For this, seeds of two shade‐tolerant trees and a heliophilous tree, native to this region, were sowed beneath the canopy of pioneer shrubs and in open spaces with and without herbaceous plants. After 2 years, our findings indicated that shade‐tolerant trees performed better beneath shrub canopies, while the heliophilous tree achieved higher establishment rates in the open spaces. Nevertheless, it seems that herbaceous plants compete with the tree seedlings and, therefore, they should be removed before conducting reforestation programs. Thus, we propose that direct seeding could be an efficient reforestation strategy, but the regeneration autecology of the tree species selected for this task, as well as their competitive ability in the face of the pioneer vegetation, must be carefully evaluated before seeding.