Just one fifth of the world's original forest cover remains in large tracts of relatively undisturbed forest areas, referred to as frontier forests (Bryant et al. 1997). Only 3% of the world's frontier forests occur within the temperate zone, and remnant temperate forests are therefore the world's most endangered frontier forests ecosystems (Silander 2000). A globally significant fraction of temperate frontier forests and freshwater ecosystems in the Americas occurs in the Pacific Northwest region of North America and the archipelago region of southwestern South America (Lawford et al. 1996). The latter region includes the sub-Antarctic Magellanic ecoregion (49-56oS), one of the world's 24 most pristine ecoregions (Mittermeier et al. 2003), which today offers a unique natural laboratory for subpolar research, which was overlooked until recently (Rozzi et al. 2006, 2012, Contador et al. 2012, Rozzi & Jiménez 2014).
The austral South American temperate forest biome (35-56oS) including its Magellanic Sub-Antarctic ecoregion is globally significant because:
- It is the largest expanse (15.6 million ha) of native temperate forest remaining in the Southern Hemisphere (Armesto et al. 1998);
- It hosts the world's largest wetland ecosystems south of 42oS, including 4.4 million ha of peat bogs (Arroyo et al. 2005);
- As a result of its isolation from other forested biomes, it presents a remarkably high percentage of endemic species (e.g., nearly 90% of its 160 woody species, ca. 60% of bryophyte species, and 45% of 147 vertebrates (Rozzi et al. 2008); and
- Due to its remoteness from most populated and industrialized centers, today it has one of the least polluted rainwaters, and freshwaters in the globe offering a type of pre-industrial baseline for comparative research with Northern Hemisphere temperate and subpolar ecosystems (Rozzi et al. 2012).
In addition to the above ecological features, the sub-Antarctic region, south of 45oS, stands out because it harbors one of the lowest human population densities within temperate latitudes (0.14 inhabitants/km2), conserving more than 70% of its pre-Columbian habitat extent; and is the home of the most threatened indigenous cultures and language families in southern South America, the Fuegian ethnic complex (Rozzi et al. 2006).
Until the 20th century, high-latitude ecosystems in southwestern South America (Fig. 1) remained largely free of direct modern human impact due to their remote location, lack of terrestrial connectivity, and restricted access to areas under control by the Chilean navy. However, at the beginning of the 21st century, construction of new access roads through primeval forests has increased the connectivity of this region with the mainland, and the Chilean navy is significantly reducing its presence. Concomitantly, the sub-Antarctic region is now facing imminent threats from various national and international development projects. The major ones include damming of several major rivers to generate hydroelectric power demanded by industrial growth in central Chile, broadening of the present road network, expanding salmon-farming industry into pristine fjords, lakes and estuaries, increasing unregulated tourism on uninhabited islands, and rapidly spreading exotic species (e.g., American beaver, Anderson et al. 2006, 2008, American mink, Crego et al. 2015, 2016, Yellow jacket wasp, Rendoll et al. 2016).