INVESTIGADORES
DEFOSSE Guillermo Emilio
artículos
Título:
Seedling dynamics of Festuca spp. in a grassland of Patagonia, Argentina, as affected by competition, microsites, and grazing
Autor/es:
DEFOSSÉ, G. E; ROBBERECHT, R.; BERTILLER, M. B.
Revista:
JOURNAL OF RANGE MANAGEMENT
Editorial:
Society For Range Management
Referencias:
Lugar: Lakewood; Año: 1997 vol. 50 p. 73 - 79
ISSN:
0022-409X
Resumen:
The effects of competition,
grazing and microsites on seedling dynamics of Festuca spp. were investigated in a semiarid steppe of Patagonia,
Argentina. In an exclosure and an
adjacent grazed area, the level of root competition for seedlings was
controlled through root exclusion tubes (0.1 m diameter, 0.4 m long) installed
adjacent to 7 similarly-sized Festuca
pallescens plants and in the interspace between F. pallescens plants. Seedling
dynamics at the phenological stages of a) recently emerged and up to 4 leaves and
b) 5 leaves and up to 1 tiller were followed inside the tube area (no
competition) and in paired circles (competition) for approximately 3 growing
seasons. Peak density of Festuca spp. seedlings occurred in fall
and early spring when water content in the first 0 to 5 cm of the soil was
above 8%. Seedling densities of Festuca spp. at the 2 phenological
stages were significantly reduced by grazing.
At the phenological stage of 1 to 4 leaves, seedlings were not affected
by root competition although their densities were significantly higher for
seedlings adjacent to F. pallescens plants
than in the interspace between pants.
This was due to higher soil water content in these areas throughout the
season in the 0 to 5 cm of the soil. Seedling densities at the phenological
stage of 5 leaves and up to 1 tiller were significantly higher when there was
no competition from neighboring grass plants as compared to seedlings exposed
to competition. In regard to microsite differences, seedling density was
significantly greater in the interspaces than adjacent to mature plants. These
results suggest that although higher seedling densities can be obtained by
excluding the area from grazing, interspecific competition for soil water
during the summer drought period can act as a barrier for further Festuca spp. seedling establishment.