Pollen production of Chenopodiaceae species at habitat and landscape scale in Mediterranean salt marshes: An ecological and phenological study

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Annual pollen production was calculated in seven species of Chenopodiaceae at the Odiel Marshes Natural Park (SW Spain) in 2006 using pollen/flower production and density of the reproductive structures of each species. Estimates of the density of plants were used to calculate the pollen production of the habitat. The results range from 760 million pollen grains/m 2/yr in low marsh to 1350 million pollen grains/m 2/yr in middle marsh. Then, based on the percentage of cover for these habitats with respect to the total landscape area, the pollen production per surface unit of the landscape was calculated. Phenological data were recorded weekly for the species throughout 2006 and 2007. Results show that two of the seven species, Suaeda vera and Arthrocnemum macrostachyum, flower before the summer temperature peak, and the other five after. With these data, the weekly pollen production per species and per surface unit was calculated for both years, based on the pollen production per plant estimated for 2006. Airborne pollen grain concentrations were monitored by a Burkard Volumetric Spore Trap, and Chenopodiaceae pollen concentrations were determined weekly. These data were related to the weekly pollen production in the field. Results show that only two species, Atriplex halimus and Suaeda vera, were significantly correlated to airborne pollen concentrations, and that high marsh and saline soil habitats were the most important sources for airborne pollen. These results are discussed with regard to the effect the different plant heights have on pollen dispersion.