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

Direct seeding is a reforestation technique that allows introducing a great variety oftree species in degraded areas with less logistics, but tree establishment rates areusually low because developing plants do not tolerate the high sun exposure,extreme temperatures, and low soil moisture that prevail in these habitats. This leadsto the proposal that seeds should be planted beneath shrubs or herbaceous plantsthat ameliorate harsh abiotic conditions, although this can also trigger interspecificcompetition and impair the performance of developing trees. This study aimed to testthese proposals in dry forests in northwest Argentina. For this, seeds of two shadetolerant trees and a heliophilous tree, native to this region, were sowed beneath thecanopy of pioneer shrubs and in open spaces with and without herbaceous plants.After 2 years, our findings indicated that shade-tolerant trees performed betterbeneath shrub canopies, while the heliophilous tree achieved higher establishmentrates in the open spaces. Nevertheless, it seems that herbaceous plants compete withthe 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 thistask, as well as their competitive ability in the face of the pioneer vegetation, mustbe carefully evaluated before seeding.