Invasion by nonnative woody species poses a major threat to the environment, biodiversity, and economies worldwide. Nahuel Huapi National Park in Argentina is a protected area for habitat conservation that harbors several invasive Pinaceae species, where Douglas-fir [Pseudotsuga menziesii (Mirb.) Franco] is one of the most aggressive and abundant conifer tree invaders. Management of invasions in protected areas must include efficient, easy to deploy, and cost-effective techniques, while reducing the impact on native ecosystems. Because the region has no control measures applied other than conventional felling, we analyzed the effectiveness of two systemic herbicides (glyphosate and aminopyralid + triclopyr) at two different concentrations, applied with the drill and fill method. We then quantified defoliation of P. menziesii trees 6, 12, and 24 mo after application and performed an economic cost analysis to determine profitability. For the application, the trees were grouped into diameter at breast height classes and randomly assigned to one of the four treatments. Herbicide doses were adjusted according to tree size. We found that glyphosate at high concentrations completely defoliated 33% of the trees after 6 mo and 87% after 12 and 24 mo. Glyphosate at low concentrations defoliated almost 30% of the trees after 24 mo, most of which were smaller trees. The aminopyralid + triclopyr treatment did not produce significant defoliation at any of the tested concentrations. When compared with conventional felling, the drill and fill method was found to reduce removal costs by 98%. We observe that differences in costs are mainly due to dead trees that remain standing, decompose slowly, and do not generate costs associated with their removal and debris management. Drill and fill is a suitable method for treating scattered trees in a native forest community, with reduced environmental consequences compared with other removal techniques currently applied within conservation areas of the Patagonian forest.

Although Chile has been establishing marine protected areas since the 1960s, studies to identify representative areas for marine biodiversity conservation at the ecoregional scale are lacking. Using the Marxan decision support tool we conducted a systematic planning process to identify High Conservation Value Areas in the channels and fjords of the southern Chile ecoregion. We involved 74 experts and other stakeholders in identifying conservation features, setting targets and compiling distribution data. Current distributions of 39 features were used in Marxan analyses. In one scenario we locked planning units that contained the Francisco Coloane Marine Protected Area. In a second scenario we also excluded planning units that overlapped with Appropriate Areas for Aquaculture, defined by the Chilean government's coastal zoning process. One-hundred percent of the proposed conservation targets were met in both scenarios. Although the distribution of 12 conservation features overlapped to a certain extent (>10%) with Appropriate Areas for Aquaculture, Marxan identified conservation solutions avoiding these areas. Our suggested portfolio of High Conservation Value Areas comprises a network of 33 sites, covering 99,432 km2 (12% of the ecoregion). These results provide the first science-based roadmap for decision makers and conservationists, and were used by the Chilean government in its coastal zoning process to define priority areas for conservation. Consequently, salmon farming has been excluded from Tierra del Fuego island.