Pollen deposition in the boreal forest of west-central Canada

Eun Ju Lee, Norm C. Kenkel, Thomas Booth
1996 Canadian Journal of Botany  
Deposition of tree and tall shrub pollen was examined along a 5.5-km transect in mixed boreal forest in west-central Manitoba, Canada. Annual pollen deposition averaged ca. 6850 grains/cm2 in 1992, with jack pine contributing 67.3% and spruce 24.5% of the total. In general, flowering plant species released their pollen in early to late May, while conifer (spruce and pine) pollen release occurred in early to mid-June. Pollen deposition was poorly correlated with relative species abundance in the
more » ... community, with some species (e.g., jack pine) being over-represented in the pollen rain and others (e.g., aspen poplar) being under-represented. In 1993, spruce pollen deposition was 63% of that in 1992. By contrast, total pollen deposition by jack pine showed little variation from 1991 to 1993. However, pollen release dates varied between years, occurring earlier in years with warmer spring temperatures. Jack pine pollen release exhibited diurnal variation, with the majority of pollen being released during daylight hours on warm, sunny days. RCsumC : Les auteurs ont examine la dCposition des pollens d'arbres et d'arbustes le long d'un transect de 5,5 km dans la for& boreale mixte du centre-ouest du Manitoba. En 1992, la deposition annuelle totale de pollen a atteint en moyenne environ 6850 grains/cm2, la contribution du pin gris Ctant de 67,3% et celle de 1'Cpinette de 24,5% du total. En gCnCral, les plantes B fleurs rellchent leur pollen du dCbut la fin de mai, alors que les conifires (Cpinette et pin) le font au dCbut de juin. La dCposition du pollen montre une faible corrClation avec l'abondance relative des espkces dans la communautC, certaines espkces Ctant (e.g., pin gris) sur-reprCsentCes dans la pluie pollinique et d'autres (e.g., le peuplier faux-tremble) sous-reprCsentCs. En 1993, la dCposition pollinique de 1'Cpinette atteint 63% de celle de 1992. Au contraire, la dCposition pollinique du pin gris montre peu de variation de 1991 B 1993. Cependant, les dates de rellchement du pollen varient entre les annCes, survenant plus t8t au cours des annCes aux temperatures printanikres les plus chaudes. Le rellchement du pollen du pin gris suit une variation diurne, la majorit6 du pollen Ctant reliche pendant les heures du jour, au cours des journCes chaudes et ensoleillCes.
doi:10.1139/b96-153 fatcat:jiyan35vijasvmbmwwzzaoiy6y