Vegetative Propagation: A Tool to Enhance Conservation and Management of Xaxim (Dicksonia sellowiana), an Endangered Tree Fern

Abstract

Before starting any species conservation strategy, it is essential to know which is the most effective propagation method, even more so if it is about rare and/or endemic species. Our goal was to evaluate a method of vegetative propagation of xaxim (Dicksonia sellowiana), an endangered tree fern from the Atlantic Forest, under different light conditions. We conducted two experiments on an experimental farm in the Araucaria Forest domain. One experiment was installed under an Atlantic Forest canopy (shade), and the other was installed in an open area surrounded by a forest with direct sunlight (without shade). All individual plants were standardised in height and frond number by removing all fronds and removing lower trunk material where trunks were longer than 50 cm. We tested three different propagule treatments: whole propagule (1 propagule), propagules cut in half lengthwise (½ propagule) and propagules cut into four equal parts lengthwise (¼ propagule). Each experiment was conducted in a randomised complete block design with four replicates. We evaluated survival, total height and diameter at ground level 6 and 10 years after the implantation, as well as the increment in those years. For survival data, the interaction between shade condition and propagule manipulation method was nonsignificant (p = 0.256) (joint analysis of experiments), and survival rate was higher for shaded propagules (58%) when compared with propagules exposed to light (41%). Higher survival was also observed for whole plants (96%). The mean height obtained from the shade experiment was statistically different among the different propagule sizes in both measurements and in the increment. The use of whole plants for transplanting of xaxim propagules significantly increased their chances of development. We recommend the establishment of whole propagules in shaded environments to ensure greater efficiency in the transplant process of this species of tree fern. The use of whole, or partial, plant propagules for propagation expands the range of strategies that can be used for the management and conservation of xaxim.