Gramineas post-fire seed bank in a Northeast Patagonian Argentinian grassland

GONZALEZ SOFÍA; GHERMANDI LUCIANA; BECKER GUILLERMO

Durban, Sudáfrica

Congreso; VII International Rangeland Congress. Proceedings of the VIIth International Rangeland Congress.; 2003

The quantitative composition of gramineas seed bank was compared in a grassland dominated by two native and perennial grasses, Stipa speciosa and Festuca pallescens, and accidentally burned (January 1999). The samples were taken in autumn 1999 and 2000 in two different sites: witness not burned (W) and site burned (B). In each site soil samples were collected at two depth: 0-1 cm and 1-3 cm. After a chilling the samples were let to germinate in a glasshouse. Every week the sampling were counted, identificated and removed. In autumn 1999, seeds from annual species Apera interrupta and Vulpia australis were found in both sites, whereas seeds from Stipa speciosa were found only in the site W. In autumn 2000, moreover seeds from perennial species Holcus lanatus and Poa spp. were found in both sites and seeds from perennial Hordeum comosum were found in the site W. Seeds from F. pallescens were not found. In both years, the seed number from gramineas was lower that total seed, but the seed number from exotic A. interrupta was high. Seed number were decrease with depth. The cover reduction from F. pallescens, H. lanatus, H. comosum and Poa spp., which were more preferable by the cattle; seed predation by rodents, early germination and seed mortality by fire decreased the total seed quantity from grasses.