Species diversity in restoration plantings: Important factors for increasing the diversity of threatened tree species in the restoration of the Araucaria forest ecosystem

Abstract

The Araucaria forest ecosystem in southern Brazil is highly threatened: less than one percent of the original forest remains, and what is left is a fragmented agro-mosaic of mostly early-to-late secondary forest patches among high-yield agriculture and timber monocultures. Forest restoration initiatives in this region aim to restore degraded areas, however the limited number of species used in restoration projects represents a missed opportunity for species-rich plantings. High diversity plantings represent a larger number of functional groups and provide a targeted conservation strategy for the high number of threatened species within this ecosystem. This study interviewed nurseries (Ns) and restoration practitioners (RPs) in Paraná and Santa Catarina states to identify what species are being cultivated and planted, and what factors are driving the species selection process. An average of 20 species were reportedly used in restoration plantings, most of which are common, widespread species. Baseline data confirms that Ns and RPs have disproportionately low occurrences of threatened species in their inventories and plantings, supporting findings from previous research. Questionnaire responses reveal that opportunities for seed acquisition are an extremely important factor in order for nurseries to increase their diversity of cultivated species. Results also suggest that facilitating species-rich plantings for restoration practitioners would only be feasible if it did not increase the time required to complete planting projects, as it would minimize their ability to keep costs low. This study proposes solutions for increasing the number of species used in restoration practice—such as developing a comprehensive species list, fostering knowledge-sharing between actors, creating seed sharing programs, and increasing coordination of planting projects. Long-term strategies involve complimenting traditional ex situ approaches with emerging inter-situ and quasi in situ conservation strategies which simultaneously provide long-term preservation of genetic diversity and increase seed production of target species. Keywords: Restoration, Araucaria forest, Threatened species, Nurseries, Restoration practitioners, Decision-making