Conversion of a monospecific plantation into a mixed plantation: combining the light-demanding Araucaria angustifolia with the shade-tolerant Cabralea canjerana

Abstract The management of plantations of the critically endangered species Araucaria angustifolia (Bertol.) Kuntze can be an opportunity to mitigate the loss of local biodiversity and to contribute to wood production and Atlantic Forest conservation. Timber species that require canopy protection can be interplanted to convert monospecific stands in uneven-aged mixed plantations. We evaluated the establishment of Cabralea canjerana (Vell.) Mart under the canopy of A. angustifolia and initial competition in an uneven-aged mixed stand. In a 14-year-old stand we planted C. canjerana seedlings in three plots and other three were maintained as pure A. angustifolia plantation. We measured growth and competition in both species using competition indices and C. canjerana environmental and physiological traits to evaluate its acclimation during establishment. Five years after planting, seedling establishment was successful: plants reached a 9-meter height and 75% survived. A. angustifolia increment in diameter at breast height (DBH) was higher in mixed plots than in pure plots. The highest C. canjerana growth was observed with up to two A. angustifolia neighbours within a 5m radius. In other three A. angustifolia stands of different ages, C. canjerana establishment was successful. According to this evidence, it is possible to convert A. angustifolia even-aged stands to uneven-aged mixed stands with beneficial results for both species. In this way, a valuable native timber species that requires canopy protection during the first years can be planted outside the rainforest. This is the first report of a mixed plantation of two native Atlantic Forest timber species.