Comparative pollen calendars from Tucson, Arizona: Durhamvs. Burkard samplers

Summary

Pollen data were compared from (1) Burkard and Durham collectors located in urban Tucson, and (2) Burkard collectors located in urban and native desert environments.Morus was the most common pollen taxon collected in urban Tucson; its presence nearly tripled annual urban pollen totals. Spearman rank correlation was. 56 (p=.05) among the annual mean value of 24 principal pollen taxa collected using the two techniques. In urban areas, several taxa (i.e., Cruciferae,Plantago, cf.Aster, Cercidium andCeltis) were collected consistently using Burkard samplers; they were infrequently collected using the Durham sampler. The Durham calendar contained spring and summerAmbrosia seasons of equal importance; whereas, the urban and desert Burkard calendars reported a dominant springAmbrosia season accounting for over 85% of the annualAmbrosia pollen. Some pollen taxa from urban areas (i.e.,Populus, Ligustrum andTamarix) remained in the urban environment; conversely, some desert taxa (i.e., springAmbrosia, Larrea, Ephedra and summerCeltis) reached urban areas. Montane pollen taxa (i.e.,Alnus, summerPinus, Quercus andArtemisia) reached urban and desert environments of the Tucson basin in similar amounts.