The development of composite dispersal functions for estimating absolute pollen productivity in the Swiss Alps

Considering the complexity of real-world pollen dispersal, a single set of parameters may be inadequate to model pollen dispersal, especially as dispersal occurs on both local and regional scales. Here we combine more than one dispersal function into a composite dispersal function (CDF). The function incorporates multiple parameters and different modes of pollen transportation, and thus has the potential to better simulate the relationship between deposited pollen and the surrounding vegetation than would otherwise be possible. CDFs based on different dispersal functions and combinations of dispersal functions were evaluated using a pollen-trap dataset from the Swiss Alps. Absolute pollen productivity (APP) was estimated at 7,700 ± 2,000 grains cm-2 year-1 for Larix decidua, 13,500 ± 1,900 grains cm-2 year-1 for Picea abies and 95,600 ± 17,700 grains cm-2 year-1 for Pinus cembra (with 95% confidence level). The results are consistent with previous APP estimates made from the same dataset using different methods.