Environmental and biodiversity impacts of variable retention forestry in Tierra del Fuego (Argentina)

SOLER, ROSINA MATILDE; SCHINDLER, STEFAN; LENCINAS, MARIA VANESSA; MARTÍNEZ PASTUR, GUILLERMO; PERI, PABLO LUIS

Montpellier

Congreso; 27th International Congress for Conservation Biology; 2015

Variable retention (VR) harvesting was suggested to maintain postharvest continuity of structural and compositional diversity, and a series of studies for Nothofagus pumilio forests in Tierra del Fuego (Argentina) seem to confirm this suggestion. VR applied in Nothofagus forests combines two types of retention: aggregates of original forest (AR) and dispersed single trees (DR). This study assesses the assumption that VR maintains mature forest conditions after harvesting by synthesizing 605 individual results from two regions of Tierra del Fuego with permanent monitoring. VR effects on (i) microenvironment, (ii) forest structure, (iii) forest reproduction, and (iv) biodiversity were investigated. AR had no effect on microenvironmental variables and forest structure, but increased the values of forest reproductio. DR did not affect microclimate and forest reproduction, but negatively affected forest structure. Species richness and abundance of native plants were significantly increased in AR; in DR richness of native plants was increased while their abundance was slightly decreased. Alien plants significantly increased in both treatments, with particularly strong effects in DR. Insect richness and abundance were hardly affected by the treatments, whereas for birds, these indicators were significantly increased in AR and in DR. Species of N. pumilio forests maintained their populations only in AR, whereas species of neighboring environments were positively affected by DR. We conclude that the ecological conditions of N. pumilio forests are influenced by VR, but direction and magnitude of the effect depend on the treatment and the kind of variable. Inside aggregates several primary forest components and conditions were maintained. Due to the considerable increase of alien species and of such from associated environments, particularly in DR, VR has still significant ecological impact over the original forest characteristics.