Variable retention forestry conserves habitat of bird species in Patagonian Nothofagus pumilio forests

LENCINAS, MV; CELLINI, JM; BENITEZ, J; PERI, P; MARTINEZ PASTUR, G

Annals of Forest Research

(ICAS

Lugar: Bucarest; Año: 2018 vol. 61 p. 147 - 160

1844-8135

Biodiversity assemblage changes across landscape, being necessary a land-sharing strategy to promote their conservation. Variable retention was proposed as an alternative to achieve both timber and conservation purposes in the management of Nothofagus pumilio forests in southern Patagonia. However, it is not clear the impact of different retention types over stenotopic and eurytopic bird species. The objective was to analyse the habitats (inside, edge or outside aggregates) and use of strata (canopy, stem, debris and floor) for different bird species under two different variable retention harvestings (aggregates and dispersed retention, or aggregates and clear-cuts). We analysed four years of bird observation data in a permanent plot belongs to PEBANPA network located in Tierra del Fuego (Argentina), as well as understory characteristics and crown cover in the same plots. Statistical analysis included uni- and multivariate tests, and comparisons with primary unharvested forest data. We evaluated nine bird species, six of which showed significantly different habitat preference in some variable retention type (Carduelis barbata, Phrygilus patagonicus and Tachycineta leucopyga in aggregated + dispersed retention, and Enicognathus ferrugineus, P. patagonicus, T. leucopyga, Troglodytes aedon and Zonotrichia capensis in aggregates + clear-cuts). Likewise, all evaluated species presented differential use of strata, and some species changed comparing harvested and unharvested forests. DCA highlighted association between species and habitats (e.g. P. patagonicus is more related to outside aggregates areas), and also that the behaviour changed according to the retention harvesting system employed, with more use of outside aggregates (as dispersed retention), but movement toward edges when clear-cuts were carried out. These results support the effectiveness of the variable retention strategy to conserve bird species. The presence of different habitats inside managed forests satisfy both stenotopic and eurytopic species requirements, as well as the adaptability of some species to different habitat features provided by variable retention harvesting.