Ecophysiological Responses and Performance Under Soil Water Restrictions of Six Sclerophyllous Species Established in a Dry Site in Central Chile

Abstract

Post-transplant shock is a key barrier to seedling establishment in Mediterranean-type ecosystems, especially when plant species are selected without consideration of functional traits conferring drought resistance. In this study, we investigated the responses to soil water restriction after the planting of six native sclerophyllous species, with growth form and leaf habit of evergreen trees (Lithraea caustica, Quillaja saponaria, Escallonia pulverulenta, Peumus boldus), semideciduous (Colliguaya odorifera), and deciduous shrubs (Vachellia caven), in a Mediterranean-type climate site in Central Chile. Seedlings were outplanted with tree shelters on a fire-disturbed site and subjected to two contrasting watering regimes during summer (2 L−1 week−1 seedling−1 for 5 months versus no watering). We assessed growth, survival, gas exchange, and midday water potential one season after planting. Species differed markedly in their drought response strategies. Deciduous shrubs such as V. caven maintained high stomatal conductance and photosynthesis despite the relatively high water potential, whereas evergreen trees sustained lower water potential through pronounced stomatal closure. The highest survival (>80%) and height increments were observed in V. caven, Q. saponaria, and C. odorifera. In contrast, E. pulverulenta exhibited positive increments in height but medium survival (63%), whereas P. boldus exhibited the poorest survival (33%), indicative of low capacity to survive and successfully establish after dry summers in Mediterranean-type climates. The different strategies of the species to cope with the post-transplant shock and the harsh conditions of the planting site may guide the selection of appropriate species to guarantee the successful seedling establishment and to support the future restoration of degraded sites characterized by long periods of drought.