INVESTIGADORES
PISSOLITO Clara Ines
artículos
Título:
Spatiotemporal Pattern of Primary Succession in Relation to Meso-topographic
Autor/es:
GARIBOTTI, IRENE ADRIANA; PISSOLITO, CLARA; VILLALBA, RICARDO
Revista:
ARCTIC ANTARCTIC AND ALPINE RESEARCH
Editorial:
INST ARCTIC ALPINE RES
Referencias:
Lugar: Boulder, USA; Año: 2011 vol. 43 p. 555 - 567
ISSN:
1523-0430
Resumen:
Vegetation in primary succession is influenced by multiple stochastic and
environmental factors at different spatial and temporal scales. In this study we
analyze the effect of meso-topographic heterogeneity on vegetation development
following the retreat of Glaciar Seco in the southern Patagonian Andes.
Composition and cover of algae, lichens, mosses, and vascular plants were recorded
in 580 plots located in different topographic positions within a chronosequence of
eight consecutive moraines. Sample plots were characterized by topographical and
surface features. Spatiotemporal patterns in vegetation composition and their
relationships to environmental factors were assessed by classification and ordination.
We recognized eight communities that correspond to four major successional stages.
The successional sequence is characterized by a physiognomic development from
pioneer saxicolous lichens (first stage) to secondary colonizer lichens (second stage),
followed by shrub colonization (third stage) and the development of Nothofagus spp.
forests (fourth stage). Alternative successional trajectories on different topographic
positions vary in the sequence of these four major successional stages, with the
trajectories on the moraine ridge-top and base not going through some of the stages.
A variance partition procedure shows that time since deglaciation and topographic
position on the moraines account for comparable amounts of vegetation variance,
emphasizing the importance of spatiotemporal analysis of vegetation development
on heterogeneous landscapes. Broad trends in vegetation development follow
environmental gradients. However, emergence and persistence of vegetation patterns
can also be attributed to dynamic geomorphic processes such as moraine slope
degradation affecting boulder distribution along the moraine foreslope. At the
landscape scale, successional trajectories converge to a Nothofagus-dominated state,
but significant variability remains in the understory due to the differential
distribution of cryptogams along the moraine topographic gradient. Convergence
is mostly related to the expansion of communities from more favorable sites towards
the harsher moraine crest, but it is not a process of gradual deterministic changes
along the different successional pathways.