Identificação de crostas biológicas do solo em áreas livre de gelo na Ilha Nelson – Antártica Marítima

The Biological Soil Crusts comprise those communities formed by the association of soil particles with microorganisms which living over the soil surface, such as mosses, cyanobacteria, algae, fungi, lichens and bryophytes. This type of soil cover can survive at extreme conditions, for example, in arid and semi-arid environments, at high or negative temperatures during most of the year, at high pH and salinity levels. The soils cover a very small fraction of the Antarctic surface, but their biological, physical and chemical properties, can be used as environment indicators about temperature and humidity changes at local scale. The objective of this work was the identification about ice free areas with and without biological soils crusts presence using the surface reflectance image in the near infrared region of the spectrum, acquired by ETM+/Landsat7 sensor and image classification procedures. The study area was located at Harmony Point - Nelson Island - Antarctic Maritime. The image classification results agreed with what was observed in all 23 plots sampled during the fieldwork. This result is due to the very distinct reflectance pattern at near infrared region showed by the snow/ice covered areas, the rocks/soils areas and the biological soil crusts areas, those are the remote sensing most common targets at the Antarctic periglacial environment. Palavras-chave: biogeography, vegetation, flora, climate, biogeografia, vegetação, flora, clima.