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G.M. Pastur et al. 2010. Indirect estimation of landscape uses by Lama guanicoe and domestic herbivorous
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2. Methodology
The study was conducted in 100 km² of Tierra del Fuego Island (Argentina) (54°20' SL, 67°52'
WL), where open lands covered 40.0% of the area (grass-lands 36.5% and peat-lands 3.5%),
forests covered 59.8% (Nothofagus antarctica forests 19.3% and N. pumilio forests 49.5%,
classified as primary unmanaged 26.8%, recently harvested 9.1% and old harvesting 13.6%),
and lagoons and lakes covered 0.2% (Fig. 1). Recently harvested forests (1-5 years) were cutted
using a variable retention method (Martínez Pastur et al. 2009), which include non-harvested
aggregated retention areas (30% of the stand) and harvested areas with dispersed retention (70%
of the stand). Old harvesting (>5 years) was done through selective cuts. Climate is
characterized by short, cool summers and long, snowy and frozen winters. Mean monthly
temperatures vary from about -7ºC to 14ºC. Absolute temperatures range from -17ºC in July to
22ºC in January. The growing season extends for about 5 months, and only 3 months per year
are frost-free. Precipitation is near 400 mm per year, and average wind speed is 8 km.h -1 ,
reaching up to 100 km.h -1 during storms (Lencinas et al. 2008). A total of 205 floristic surveys
were obtained recording the cover percentage of vegetation in different site types. Vascular
plants (Dicotyledonae, Monocotyledonae and Pteridophytae) were taxonomically classified by
species and determined their origin (native or exotic), following Moore (1983) and Correa
(1969-1998). Beside this, each species was classified according their relative abundance in
common (more than 0.02% covers in average for the entire census) or rare (less than 0.02%).
Figure 1: Study area, where: yellow = open lands, brown = Nothofagus antarctica forests, green = N.
pumilio forests (dark green = primary unmanaged, green = recently harvested, pale green = old
harvesting), and blue = lagoons and lakes.
Feces of native (Lama guanicoe) and domestic (Bos taurus and Ovis aries) herbivorous
were collected along the four seasons (spring, summer, autumn and winter). In each sampling,
four areas including different site types were selected, and five feces were collected and mixed
to complete one pool sample (n = 4 per season per herbivorous species). Pool samples were
oven-dried at 60ºC for 48 h, grounded to