Environ Monit Assess DOI 10.1007/s10661-011-2006-x Impact of land-cover change in the Southern Amazonia climate: a case study for the region of Alta Floresta, Mato Grosso, Brazil Vincent Dubreuil · Nathan Debortoli · Beatriz Funatsu · Vincent Nédélec · Laurent Durieux Received: 18 September 2010 / Accepted: 14 March 2011 © Springer Science+Business Media B.V. 2011 Abstract The transformation of forest into pas- tures in the Brazilian Amazon leads to significant consequences to climate at local scale. In the region of Alta Floresta (Mato Grosso, Brazil), deforestation has been intense with over half the forests being cut since 1970. This article first ex- amines the evolution of precipitation observed in this region and shows a significant trend in the decrease in total precipitation especially at the V. Dubreuil (B ) · B. Funatsu · V. Nédélec Laboratoire COSTEL, UMR6554 LETG du CNRS, Université Rennes 2, Place du Recteur Henri le Moal, 35043 Rennes Cedex, France e-mail: vincent.dubreuil@uhb.fr B. Funatsu e-mail: beatrixmf@yahoo.com V. Nédélec e-mail: vincent.nedelec@uhb.fr N. Debortoli Center for Sustainable Development, Universidade de Brasilia, Campus Universitário Darcy Ribeiro - Gleba A, Bloco C - Av. L3 Norte, CEP: 70.904-970 Asa Norte - Brasília-DF, Brazil e-mail: nathandebortoli@gmail.com L. Durieux Unité Espace S140, Institut de Recherche pour le Développement, Représentation de l’IRD au Brésil CP 7091 - Lago Sul, 71619 - 971 BRASILIA (DF), Brazil e-mail: laurent.durieux@ird.fr end of the dry season and at the beginning of the rainy season. The study then compares the temperatures measured in cleared and forested sectors within a reserve in the area of Alta Flo- resta (Mato Grosso, Brazil) between 2006 and 2007. The cleared sector was always hotter and drier (from 5% to 10%) than the forested area. This difference was not only especially marked during the day when it reached on average 2 ◦ C but also seemed to increase during the night with the onset of the dry season (+0.5 ◦ C). The Urban Heat Island effect is also evident especially during the night and in the dry season. Keywords Deforestation · Rainfall · Temperatures · Amazonia Introduction Several studies have highlighted the specificities of the Amazonian climate and the importance of the interactions between the forest and cli- mate system (Nimer 1989; Nobre et al. 1991; Polcher and Laval 1994; Hasler and Avissar 2006). Apart from precipitation, the forest promote the maintenance of strong humidity and a range of high temperatures (30 ◦ C to 34 ◦ C during daytime and 15 ◦ C to 20 ◦ C during the night, on average). Major modifications in vegetation cover have consequences on hydrology and climate (Lean