Combining the light-demanding Araucaria angustifolia with the shade-tolerant Cabralea canjerana: mixed plantations to produce tropical timber trees outside the rainforest

Abstract

Atlantic Forest broad-leaved trees of high timber value require canopy cover to become established. Therefore, at present, they are only harvested from native rainforests. Araucaria angustifolia (Bertol.) Kuntze is the only Atlantic Forest Gymnosperm; it requires high radiation to establish and is planted in monospecific stands. The main question was if the umbrella-shaped open canopy generated by A. angustifolia stands was enough to protect mid-successional timber species. We evaluated the establishment of Cabralea canjerana (Vell.) Mart under the canopy of A. angustifoliastands and we related growth with initial competition. In one stand, we measured environmental and physiological traits to evaluate seedling acclimation. C. canjerana establishment was successful in stands of different basal areas. Seven years after planting, C. canjerana plants reached a 12-meter height and 75% survived; the highest growth was observed with up to two A. angustifolia neighbors within a 5m radius. According to this evidence, it is possible to convert A. angustifolia even-aged stands to uneven-aged mixed stands. 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 an uneven-aged mixed plantation of two Atlantic Forest timber species.