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R.A. Diaz-Varela et al. 2010. Quantitative assessment of temporal dynamics in altitudinal-driven ecotones
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Quantitative assessment of temporal dynamics in altitudinal-driven
ecotones in a section of Valtellina Italian Alps
Ramón Alberto Diaz-Varela 1* , Silvia Calvo-Iglesias 2 , Michele Meroni 3 & Roberto
Colombo 3
1 University of Santiago de Compostela, Spain
2 University of Vigo, Spain
3 University of Milano-Biccoca, Italy
Abstract
Mountain ecotones are sensitive to climate and global change and their historical dynamics can
be used as a record and indicator of such events. Nevertheless there are relatively few studies
aiming at the quantification of their dynamics in a spatial explicit way at a detailed scale. In this
work we quantified the altitudinal shifts and spatial pattern of mountain ecotones. We applied a
novel procedure to delineate the current and former location of three characteristic mountain
ecotones, formalised as forest, tree and tundra lines in a section of Valtellina (Italian Alps). We
estimated the medians of overall decadal altitude increments in 25 m for forest line, 13 m for
tree line and 11 m for tundra line. The method also allowed us to differentiate between ecotone
advance and retreat events. We also conducted an analysis of vegetation patches morphology at
the ecotone locations, which showed significant implications in their dynamics.
Keywords: Mountain ecotones, Alps, Global change, Spatially explicit model, Digital elevation
model
1. Introduction
Mountain and boreal ecosystems are among the environments most susceptible to climate and
land use changes (Theurillat and Guisan 2001; Didier 2001). Both phenomena have the general
effect of raising of altitude driven ecotones (Didier 2001; Körner 1998; 1999). Despite the
considerable number of works dealing with the definition and environmental implications of the
upper limits of mountain vegetation, there are few works that focus on its spatially explicit
delineation. Besides, the literature offers many examples of woodland upper limits while less
attention has been paid to alpine treeless vegetation and its limits with non-vegetated rocky and
nival habitats.
The main aim of this paper is to analyse the spatial and temporal dynamics of forest line, tree
line and tundra line ecotones in alpine areas and to evaluate their fluctuations in the context of
climatic and land use change.
We tested the method in the Val Masino catchment in the Central Alps (province of Sondrio,
Lombardy region, Italy). The study area comprises two sub-catchments (Valle dei Bagni and
Val di Mello) of the Masino creek basin, comprising 83.4 km 2 of surface and with a range of
altitudes from 909 to 3432 m a.s.l. (Fig. 1). Vegetation types and patterns are closely related to
altitudinal gradients. The uppermost sectors are occupied by glaciers, bare or sparse vegetated
surfaces on rocky habitats such as screes, rocky slopes or cliffs. Below this belt different kinds
* Corresponding author. Tel.: +34 982 285 900 ext. 22482 - Fax: +34 982 285 985
Email address: ramon.diaz@usc.es
Forest Landscapes and Global Change-New Frontiers in Management, Conservation and Restoration. Proceedings of the IUFRO Landscape Ecology
Working Group International Conference, September 21-27, 2010, Bragança, Portugal. J.C. Azevedo, M. Feliciano, J. Castro & M.A. Pinto (eds.)
2010, Instituto Politécnico de Bragança, Bragança, Portugal.