Pollen dispersal at arctic treeline

Pollen dispersal of Picea mariana was studied in reference to abscission direction and long-distance pollen dispersal near Arctic treeline. This study tests two models for pollen dispersal: an advection-diffusion model described by Okubo and Levin (1989) and a proposed model where modifications were made to Okubo and Levin (1989). Pollen was passively collected up to 1300 m (2002) and 1500 m (2003) away from a P. mariana area source. I obtained mixed results; none of the three correlations between predicted and observed were significant for the Okubo and Levin (1989) model, whereas two of three trials were correlated significantly for the proposed model. The main problem with the proposed model appears to be underprediction of deposition when the source is nearby, likely due to problems with an angular argument describing the location of a Picea tree within the pollen source. Further, I experimentally determined that there was a bias toward abscission by downdrafts. This result could also explain the underprediction.