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

SOLER, R; SCHINDLER, S; LENCINAS, MV; MARTÍNEZ PASTUR, G; PERI, P

Congreso; 27th International congreso for Conservation Biology-ICCB and 4th European Congreso for Conservation Biology-ECCB.; 2015

Variable retention (VR) harvesting was suggested to maintainpostharvest continuity of structural and compositional diversity, and a seriesof studies for Nothofaguspumilioforests in Tierra del Fuego (Argentina) seem toconfirm this suggestion. VR applied in Nothofagus forests combines two types ofretention: aggregates of original forest (AR) and dispersed single trees (DR).This study assesses the assumption that VR maintains mature forest conditionsafter harvesting by synthesizing 605 individual results from two regions ofTierra del Fuego with permanent monitoring. VR effects on (i) microenvironment,(ii) forest structure, (iii) forest reproduction, and (iv) biodiversity wereinvestigated. AR had no effect on microenvironmental variables and foreststructure, but increased the values of forest reproductio. DRdid not affectmicroclimate and forest reproduction, butnegatively affected forest structure.Species richness and abundance of native plants were significantly increased inAR; in DR richness of native plants was increased whiletheir abundance wasslightly decreased. Alien plants significantly increased in both treatments,with particularly strong effects in DR. Insect richness and abundance werehardly affected by the treatments, whereas for birds, these indicators weresignificantly increased in AR and in DR. Species ofN. pumilioforests maintainedtheir populations only in AR, whereas species ofneighboring environments werepositively affected by DR. We conclude that the ecological conditions of N.pumilio forests are influenced by VR, but direction and magnitude of the effectdepend on the treatment and the kind of variable. Inside aggregates severalprimary forest components and conditions were maintained.Due to the considerableincrease of alien species and of such from associated environments,particularly in DR, VR has still significant ecological impact over theoriginal forest characteristics.