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Báo cáo lâm nghiệp: "Human land-use, forest dynamics and tree growth at the treeline in the Western Italian Alps"

Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp Original article đề tài: Human land-use, forest dynamics and tree growth at the treeline in the Western Italian Alps. | Ann. For. Sci. 63 2006 739-747 INRA EDP Sciences 2006 DOI 10.1051 forest 2006055 739 Original article Human land-use forest dynamics and tree growth at the treeline in the Western Italian Alps Renzo MOTTAa Mariano MORALESb Paola NOLAc a Dep. Agroselviter University of Turin Via Leonardo da Vinci 44 10095 Grugliasco TO Italy b Dep. de Dendrocronología e Historia Ambiental IANIGLA-CRICYT CC330 CP 5500 Mendoza Argentina c Dep. Ecoter University of Pavia Via S. Epifanio 14 27100 Pavia Italy Received 5 October 2005 accepted 9 March 2006 Abstract - Three plots were sampled along an altitudinal gradient in the upper Susa Valley Piedmont Italy on a northeastern slope from 1800 to 2300 m a.s.l. In order to reconstruct recent dynamics at this altitudinal range various techniques were used. Dendroecological methods were used to reconstruct the age structures of tree populations. Growth dynamics were investigated both by observing Basal Area Increment BAI in old and dominant trees and by comparing the BAIs within a given cambial age class in different time periods. Historical documents were analyzed as an independent data source to explain changes in establishment rate. As far as the tree establishment at the forestline and at the treeline is concerned we observed three distinct periods during the first one 1850-1930 larch establishment was reduced or prevented because of heavy grazing and the stone pine establishment was almost null because of the grazing and of the human anthropogenic removal. During the second one 1930-1960 the past heavy grazing followed by periods of moderate grazing favored the larch establishment stone pine establishment was still prevented both by grazing and by anthropogenic removal. Finally the third period 1960-present has been the period of massive stone pine regeneration. The growth rates of stone pine and larch have increased in the last decades individuals in the 100- 150- and 200-year age classes grow more rapidly in present times as compared .