Effect of spatial and temporal heterogeneity on granivory in the Monte Desert, Argentina

PAOLA L. SASSI; JORGE TORT; CARLOS E. BORGHI

AUSTRAL ECOLOGY

Año: 2004 vol. 29 p. 661 - 666

1442-9985

An important aspect of arid regions is the spatial heterogeneity resulting from differences among plant communities. There are process differences among different vegetation patches increasing variability in the functioning of the ecosystem. The purpose of this study was to estimate granivory, by studying variation of seed removal rates among patches at the local scale and variation according to seed type. We carried out experiments during four seasons in three plant communities in the Monte Desert, Argentina: ‘peladal’, mesquite forest and creosotebush. Seed trays were offered to ants, birds and rodents. Two types of commercial seeds (sunflower and millet) were used. We found that seed removal rate was significantly different among plant communities, among taxa (birds, ants and murid rodents), and among seasons, and that removal rate was higher for sunflower. Seed removal rates by murid rodents were higher than by birds or ants, and occasionally as high as those found in other deserts. The heterogeneity of seed removal patterns at the local level was as strong as that found between continents. Further studies may show similar local heterogeneity in other deserts of the world.