Retention Forestry in Southern Patagonia: Multiple Environmental Impacts and Their Temporal Trends

Abstract

Harvesting with variable retention (VR) applied in Nothofagus forests combines two types of retention: patches of original forest (aggregates) and single isolated homogeneously distributed trees (dispersed). This study assesses the assumption that VR maintains mature forests conditions after harvesting by synthesizing 605 individual results from long-term studies in two regions of Tierra del Fuego (Argentina) with permanent monitoring. VR effects on (i) forest structure, (ii) microenvironment, (iii) biodiversity, and (iv) forest reproduction, were investigated. Aggregated retention had no effect on forest structure and microenvironmental variables, but increased biodiversity variables and forest reproduction compared to unmanaged primary forest (control). Dispersed retention negatively affected the forest structure, increased biodiversity, but did not affect microclimate and forest reproduction when compared to primary forest. Thus, the ecological conditions of N. pumilio forests are influenced by variable retention harvesting, but direction and magnitude of the effect depend on the treatment and differ among groups of variable. Inside aggregates several primary forest components and conditions were maintained.