Recent Pollen Spectra from the Deciduous and Coniferous‐Deciduous Forests of Northeastern Minnesota: A Study in Pollen Dispersal

Abstract

Abstract.Pollen samples were taken along nine transects across local vegetational belts bordering bogs or ponds in overall deciduous and coniferous-deciduous forest regions.

Modern pollen rain–vegetation relationships along a forest–steppe transect in the Golestan National Park, NE Iran

“…2) a été tracé à l'aide du logiciel GpalWin (Goeury, 1997 La situation se complique encore pour les assemblages de pollen de surface car la pluie pollinique n'est pas limitée aux communautés végétales locales. La végétation extra-locale et surtout régionale contribue aussi notablement à la pluie pollinique (Janssen, 1966). À ces facteurs s'ajoute aussi le rôle de la topographie (Markgraf, 1980) La comparaison des pourcentages polliniques avec les abondances de végétation en milieu forestier montre que Zelkova est sous-représenté dans la pluie pollinique actuelle d'un facteur > 4, même sous une canopée fermée où Zelkova forme 100% du couvert.…”

Modern pollen-vegetation relationships on the Southeast Caucasus

“…Accordingly, the contribution of regional pollen sources (trees more than a few hundred m away) would be small (< 15%). Jacobson & Bradshaw (1981) found their predictions on the assumption that pollen dispersal to small basins is dominated by low velocity winds from the trunk space of the adjacent forest (Tauber 1965) and gravity from nearby trees (Jansscn 1966, Andersen 1970.…”

Recent Pollen Spectra in two Small Mountain Basins of the Ligurian Apennines (Northern Italy)

“…Cosrnrren, Picea, Snriibrrcrrs; nevertheless, it gives a more local picture than the phytosociological relev& of the whole basin, due to its close proximity to the bog. The 500 m distance is just regarded a s the boundary for the extralocal pollen rain, with regard to a sample point, while regional contributions come from a distance between 500 m and a few kilometers (Heim 1970, Janssen 1966, 1973, 1981.…”