INVESTIGADORES
MARTINEZ PASTUR Guillermo Jose
artículos
Título:
A comparison of impacts from silviculture practices and North American beaver invasion on stream benthic macroinvertebrate community structure and function in Nothofagus forests of Tierra del Fuego.
Autor/es:
MP SIMANONOK; CB ANDERSON; G MARTÍNEZ PASTUR; MV LENCINAS; JH KENNEDY
Revista:
FOREST ECOLOGY AND MANAGEMENT
Editorial:
ELSEVIER SCIENCE BV
Referencias:
Lugar: Amsterdam; Año: 2011 vol. 262 p. 263 - 269
ISSN:
0378-1127
Resumen:
The sub-Antarctic biome of South America is the world’s southernmost forested ecosystem and one of the last 24 remaining pristine wilderness areas on the planet. Nonetheless, the region confronts various anthropogenic environmental impacts, such as the invasive North American beaver (Castor canadensis) and harvesting (shelterwood cuts and variable retention), particularly for stands of Nothofagus pumilio. The effect of both factors is apparent in both aquatic and terrestrial systems within the area of disturbance. To understand the influence of these disturbances on sub-Antarctic watersheds, we characterized physical habitat conditions (pH, dissolved oxygen, conductivity, temperature, stream size, distance to riparian forest, bank slope, substrate heterogeneity, benthic organic matter) and sampled invertebrate community structure (density, richness, diversity, evenness) and function (biomass, functional feeding group percent) in 19 streams located on Tierra del Fuego Island. To explain the effects of beaver invasion and harvesting we compared the physical and biotic variables among four habitat treatment types: a) beaver meadows, b) shelterwood cut harvested areas without riparian buffers, c) variable retention harvested areas with riparian buffers, and d) unmanaged old-growth primary forests. Most habitat variables were similar from all sites, except for dissolved oxygen (significantly higher in pristine streams of unmanaged old-growth primary forests) and distance to riparian forest (significantly greater in shelterwood cut harvested areas without riparian buffers and beaver meadows). Benthic communities in beaver meadows had significantly lower diversity, compared to streams of unmanaged old-growth primary forests and variable retention harvested areas with riparian buffers, while shelterwood cut harvested areas without riparian buffers presented intermediate values. Functionally, the benthic community in beaver meadows displayed a reduction of all functional feeding groups except collector-gatherers; again variable retention harvested areas with riparian buffers were similar to unmanaged old-growth primary forest streams, while shelterwood cut harvested areas without riparian buffers occupied an intermediate position. These results indicated that current forestry practices that include both variable retention and legally mandated riparian buffers are effective in mitigating impacts on stream benthic communities. In conclusion, beaver impacts were overall greater than the effects of harvesting, which are of note considering that the sites we studied were streams flowing through beaver meadows, rather than active beaver ponds.