Biodiversity conservation in temperate forests: experiences from South America

LENCINAS, MV

Conferencia; INTERNATIONAL SCIENTIFIC CONFERENCE Forest science for people and societal challenges. The 90th "Marin Drăcea" INCDS Anniversary; 2023

Temperate forests are those located between tropical and boreal regions. They cover around 25% of the world’s forest area and are distributed from 25 to 50º latitude in both hemispheres, spanning in a wide variety of climates and precipitation regimes, from dry to rainforests. They historically suffer several anthropic impacts (e.g., logging, farming, mining, hunting, urbanization, climate change, biological replacement or invasion) as well as natural disturbances (e.g., catastrophic events as volcanic eruptions or tsunamis), with strong effects on biodiversity and habitat loss (e.g., deforestation, pollution, fragmentation, changes of land use by replacement with exotic tree plantation). Biodiversity in temperate forests greatly depends of some old-growth characteristics (such as large old and dead trees), which have been drastically reduced in temperate forests around the world. Therefore, this biodiversity faces local extirpation or extinction, even in countries that remain largely forested. The main challenges for biodiversity conservation in temperate forests are to protect endangered and/or emblematic forest types and/or species, conserve particular habitats within some forest types, and maintain connectivity between temperate forest patches. Usual and traditional practices implemented worldwide for conservation are to enlarge the land and quantity of protected areas, and set aside forests with management restrictions because it is often considered these will be best preserved by non-intervention. This target is generally expensive and inefficient because forests are usually intermingled with other ecosystem types in the landscape matrix. On the other hand, the management exclusion cannot be enough for preservation in the long term in protected forests where biodiversity values are legacies from past disturbances, as fires, grazing or selective logging, and silviculture could play a fundamental role when forests need active management to maintain valuable characteristics. Also, conservation strategies should include careful planning and regulation of land use in the surrounding matrix of a protected area, environmental education, and network development among conservationists, scientists, managers and private landowners. In South America, temperate forests occupy a long but latitudinally narrow strip, extending from 35 to 55ºS in the southernmost extreme of the continent. The more usual conservation strategy is to split forest remnants with high conservation value from management, to avoid impacts and modifications. However, those areas requiring protection are usually more accessible, highly-priced or more suitable for productive uses, and are usually in private hands. Therefore, other conservation strategies are proposed, for example, a combination of extensive protected areas that enclose wild landscapes (land sparing) with small and valuable forest remnants in managed areas (land sharing). Experiences in monospecific Nothofagus forests, obtained from variable retention management, are presented as evidence of this biodiversity conservation strategy implemented in South America.