INSTITUTO ARGENTINO DE NIVOLOGIA, GLACIOLOGIA Y CIENCIAS AMBIENTALES
Unidad Ejecutora - UE
Colonization of mid- and late-Holocene moraines by lichens and trees in the Magellanic sub-Antarctic province
GARIBOTTI, IRENE A.; VILLALBA, RICARDO
Año: 2017 vol. 40 p. 1739 - 1753
Understanding the process of primary successionis a relevant topic in restoration and global changeecology, and provides the basis for classic dating methodsin geomorphology, such as lichenometry and dendrochronology.The aim of this study is to investigate the colonizationby lichens and vascular plants of two pro-glacialchronosequences encompassing the late- and mid-Holoceneperiods in the sub-Antarctic sub-region of SouthAmerica. We use this information to address questionsrelated to the pattern of Magellanic forests recovery afterdisturbance and the applicability of lichenometry for developingglacier retreat chronologies. Progression of successionto a state with high vascular plant cover was slow, andsome moraines remained unforested for about 2000 years.Our results contrast with previous reports indicating aquick development of mature forest states on disturbed terrains,suggesting large regional variability on the course ofsuccession. Environmental conditions seem propitious forlichens that colonize immediately after moraine formation.Lichens grow at relatively high rates in comparison to otherworld areas, but half as fast as in Antarctica and sub-Antarcticislands. Growth rates for the Rhizocarpon Ram. em.Th. Fr. sub-gen. Rhizocarpon group increase with lichensizes up to ca. 50 mm and decrease in larger thalli, leadingto a sigmoidal lichenometric growth curve that extendsthe applicable range of lichenometry to the last 5700 yearsin dry sites in the Magellanic province of the sub-Antarcticsub-region. Our results suggest that lichenometry is aneffective technique in multi-proxy approaches for reconstructingglacier fluctuations, and agree with early studiesin Antarctica suggesting that lichen annual growth rate is asensitive attribute for the biomonitoring of climate changes.