Managed and spontaneous regeneration of trees in a reforestation trial in Costa Rica

Rosa-Maria Ronay und Stephan Gräber arbeiten 2022 an ihren Masterarbeiten im Rahmen des COBIGA-Projektes. Rosa misst das Wachstum der ab 2012 gepflanzten Bäume auf der Finca Amable und auch der zwischen den gesetzten Bäumen wachsenden spontanen Verjüngung. Die Praktikantin Paulina Schroeren (Mitte) unterstützt sie dabei. Obwohl die natürliche Sukzession auch sehr rasch erfolgen kann, ist das nicht immer der Fall. So kann der Farn Dicranopteris große Flächen bedecken und die Sukzession verhindert. Stephan untersucht, wie lange so die Entwicklung zum Wald blockiert wird. Da die wenigen Bäume in den dichten Farnbestände praktisch nicht zugänglich sind, werden sie über eine Drohne erfasst.

Since the mid-20th century, forest areas have been continuously cut down and cleared in Central and South America in order to convert them into intensively managed pastures and arable land. The resulting loss of species and habitats, as well as carbon sequestration, is serious. The "Golfo Dulce" region is one of the most species-rich areas in Central America with over 2700 plant species and more than 700 tree species (Weissenhofer, 2008). Therefore, the preservation of this area is of great importance. With the reforestation projects in the area around La Gamba, attempts are being made to preserve biodiversity on the one hand and to link isolated forest areas with one another on the other. The protection of rainforests, as well as the reforestation of deforested areas through active reforestation, are important instruments for protecting biodiversity and counteracting climate change (Caughlin et al., 2016). The cost of reforestation to accelerate ecological succession varies with the methods used. Active reforestation is considerably more expensive due to the high cost of planting trees and annual maintenance, while natural regeneration is relatively inexpensive.
In the vicinity of the tropical station La Gamba, former cattle pastures were reforested between 2012 and 2015 and since 2016 the spontaneous vegetation on these reforested areas has been investigated. The last survey took place in 2019. The term spontaneous vegetation includes all naturally occurring, woody plants that have developed on the plots in addition to the trees that have been planted.

v.l.n.r. Rosa-Maria Ronay, Paulina Schroeren und Stephan Gräber 2022 in La Gamba.