. Effects of topography, soil moisture, wind and grazing on Festuca spp. seedlings in a Patagonian grassland

DEFOSSÉ, G.E; BERTILLER, M.B; ROBBERECHT, R.

JOURNAL OF VEGETATION SCIENCE

WILEY-BLACKWELL PUBLISHING, INC

Año: 1997 vol. 8 p. 677 - 684

1100-9233

The effects of topography, soil moisture, wind andgrazing on the emergence and survival of seedlings of Festucaspp. were examined in the steppe zone of Patagonia, Argentina. Ungrazed and grazed field treatment plots were established on a plain and a north-facing slope at the Media LunaRanch (43° 36´ S, 71° 25´ W). On the leeward and windwardsides of each of 15 Festuca plants, 0.1 m × 0.4 m quadratswere censused bimonthly for seedling emergence and survivalover three growing seasons. Three categories were distinguished: recently germinated and up to the first leaf, two tofour leaves, and from five leaves up to one tiller. Soil moisturecontent, litter cover and frost heaving effects were also determined for each treatment at each sampling date. Festuca spp.showed two emergence peaks, one in late fall and the other inearly to mid-spring. Seedling emergence was significantly correlated with soil moisture content in the 0-5 cm of the soil duringthe three growing seasons. Seedlings that emerged in the fallhad higher survivorship than those that emerged in spring.Seedling emergence and survival was significantly (p < 0.01)lower on slopes, in the grazing treatment, and on windwardsides of adult plants. In this grassland, an increase in theavailability of safe sites for seedling emergence and survivalmight be achieved by protecting vegetation from grazing,particularly on north-facing slopes.