Subalpine Nothofagus and Araucaria forests across an environmental and disturbance gradient in South Central Chile: a floristic approach (Submitted)
Pauchard, Aníbal 1, Ugarte, Eduardo A. 2, Finckh, Manfred 3 & Alaback, B. Paul 1
1 School of Forestry, University of Montana. MT 59812, USA.
pauchard@forestry.umt.edu
2 Facultad de Ciencias Naturales y Oceanográficas. Universidad
de Concepción. Casilla 160-C, Concepción, Chile.
edugar@udec.cl
3 Manfred Finckh. Institut für Allgemeine Botanik, Abt. Systematik.
Universität Hamburg. Ohnhorststr. 18. D-22609 Hamburg, Germany.
mfinckh@botanik.uni-hamburg.de
Abstract
Vegetation response to environment and disturbance were studied
in a subalpine volcanic national park in southern Chile to better
understand how this unique flora responds to complex gradients,
and to provide baseline information for environmental assessment
studies in the region. We describe community assemblages and species
distribution patterns in a Nothofagus spp. - Araucaria
araucana forest mosaic using physiognomic vegetation mapping,
phytosociological classification methods and an indirect gradient
analysis. Four physiognomic types were defined including 3 forest
types and a lake shore shrubland. Six plant communities were defined
(4 forest, 1 shrubland and 1 grassland). Most of the study area
was dominated by a mixed Nothofagus antarctica A. araucana
forest followed by N. dombeyi A. araucana forests.
A. araucana had multimodal diameter distributions reflecting
a long history of fire and volcanic disturbances. Detrended correspondance
analysis suggested that floristic patterns followed a disturbance
and geomorphic gradient. Temperature extremes and disturbance
types were hypothesized as the most critical factors determining
changes in dominant species distributions. The gradient was closely
correlated with vegetation structural complexity. We found 115
species belonging to 45 families in the 241 ha study area. The
highest diversity occurred in pure N. antarctica forests,
intermediate in total cover and height. Despite the 1000m elevation
and the study site location within the core of a national park,
18% of the species were exotics, associated mostly with human
disturbed areas. Combining both phytosociological and ordination
methods helps to better understand and conserve these subalpine
environments in the southern Andes.