Dispersal of amaranthaceae and chenopodiaceae pollen in the atmosphere of extremadura (sw spain)

Abstract

A study over six consecutive years of the pollination dynamics of the Amaranthaceae and Chenopodiaceae in Badajoz, and a comparative study over three years with stations in Mérida and Cáceres showed that there were different factors affecting this process. Thus, the proximity of croplands was found to be important in determining the magnitude of the concentrations, and this was also confirmed with a study of the concentrations measured directly in the croplands. Autumn and summer rainfall was found to affect, and also to have a certain influence on the length of the flowering period. The daily variations in pollen levels were studied in relation to meteorological parameters, finding a correlation that was positive with respect to temperature and negative with respect to atmospheric humidity and the distance travelled by the wind, i.e. airflow measured in hm with a revolving-cup anemometer. These correlations were the same in all three of the localities studied. The direction of the wind, however, was found to have different effects according to the locality studied. This is explained by their positions relative to the irrigation zones in the region. The pattern of diurnal pollen release from these taxa shows the greatest levels to be reached between 10:00 and 12:00 hours in Mérida as well as in Badajoz. In Cáceres, however, the distribution throughout the day was very even, with few hourly variations. This may be due to the sparse representation of these species in the neighbourhood of the Cáceres trap, with the pollen having been transported from sources that were farther away. © 2000 Taylor & Francis Group, LLC.