A preliminary ecological study of the Alpine flora of Popocatepetl and Iztaccihuatl

Abstract

At every 100-meter level between 3,700 and 4,300 meters on Popocatepetl and lztaccihuatl, five meter-square quadrats were used for determining species presence and frequency. From the resulting data several observations about the alpine flora were made. With an in crease in altitude, there was a reduction in number of species and number of individual plants present. The quadrant data clarified species distrihution patterns and showed that most species have a restricted altitudinal rango. Only two species extended from the 3,700-meter level to the 4,300-meter level. With the data obtained, it was possible to evaluate the relative importance of each of the species. Only a few species were extremely important, and a large number of species had little importance. Adjacent stands and stands at equal altitudes were compared by the community coefficient method. No two stands had the same species structure, but adjacent stands usually had a community coefficient of at least 44 percent. Stands in Pinus hartwegii forest, however, were distinctly different from those in meadows, as indicated by the low community coefficients when the two were compared. Four major phases of the alpine meadows were designated and briefly characterized. Although these phases did not have sharp boundaries, they usually could be readily recognized in the field.