Native forest management in subtropical South America: long-term effects of logging and multiple-use on forest structure and diversity

If logging and forest multiple-use are to be compatible with biodiversity conservation, then forest structure, composition and diversity must be expected to recover from the disturbance and eventually return to their former levels. Here we evaluate the long-term effects of selective logging and forest multiple-use on Southern Brazilian subtropical Araucaria mixed conifer-hardwood forest resilience at the landscape-scale. Long-term effects of different management regimes were compared between control undisturbed forests and forest stands subjected to early (55 years before this study) and recent (13 years) selective logging followed by undisturbed postharvest periods, and forest fragments subjected to selective logging followed by unregulated multiple-use by private landowners. Forest structure (tree density, basal area and height, and regeneration density) in early-logged areas was indistinguishable from control areas. Fragmentation and chronic disturbance, however, degraded forest fragments and kept them at early successional stages, with higher tree density, reduced basal area and scarce or absent regeneration. Mixed forests showed compositional resilience in the angiosperm component but not in the conifer component. Chronic disturbance kept forest fragments floristically away from mature and undisturbed secondary forests. Species richness in control and recently-logged plots did not differ significantly and was higher than richness in early-logged plots. Species richness was much reduced in degraded forest fragments. Density of the conifer Araucaria angustifolia, characteristic of the mature forest, was reduced in the fragments and in logged stands. We discuss how native forest management practices can be implemented to contribute positively to the conservation of the Araucaria mixed forest biodiversity.