资源环境科技发展态势分析平台

Most native Araucaria forests exist on small farms in the southern region of Brazil, with only a small area (< 1%) of coverage still present in the protected areas of mature forests. Current law restricts forest management for timber production in native Araucaria forests by prohibiting harvesting the main tree species-Araucaria angustifolia and other important commercial timber species. As a consequence, the forested areas of some small farms have been illegally converted to other land uses, resulting in the area of native Araucaria forest coverage in southern Brazil having been significantly reduced in recent decades. To gain a better understanding of the consequences of managing native Araucaria forests on small farms for timber production, we used a growth model to simulate nine different harvesting scenarios using different harvest intensities and cutting cycles to simulate A. angustifolia's long-term recovery after harvesting. The harvesting scenarios considered sustainable for supplying A. angustifolia timber were further tested in simulations of overall timber forest management that included harvesting angiosperm tree species in addition to A. angustifolia. The simulations were performed with data collected from 48 plots established on 19 small farms located in southern Brazil. Of the nine harvesting scenarios tested, four were considered sustainable for producing A. angustifolia timber: (1) removing 10% of the A. angustifolia basal area (G(arauc) in m(2) ha(-1)) in 5-yr cutting cycles; (2) removing 20% of the G(arauc) in 10-yr cutting cycles; (3) removing 35% of the G(arauc) in 20-yr cutting cycles; and (4) removing 40% of the G(arauc) in 25-yr cutting cycles. These four sustainable A. angustifolia harvesting scenarios remained sustainable when managing the forest as a whole by including some angiosperm tree species harvesting as well. This indicates that managing forests for timber production may be a promising pursuit to develop on the small farms of southern Brazil.