Klemow, K.M. 1989. A DEMOGRAPHIC ANALYSIS OF COMMONNESS AND RARITY AMONG CO-OCCURRING HERBACEOUS PLANT SPECIES. Contributed paper: Pennsylvania Academy of Science meeting. Abstract: Journal of the Pennsylvania Academy of Science 63:50.
A community of herbs co-occurring in an abandoned limestone quarry near Syracuse, New York was examined over a 6-year interval. The original purpose of the study was to determine whether the species differed in their patterns of abundance, and if so, whether the common species had any demographic attributes that were consistently different from the rare species. In analyzing the patterns of germination, survival and reproduction among the various species, the definition of abundance itself came into question, however. Three measures of abundance were defined: the total number of flowering individuals observed during the six years, the mean number of established individuals observed per sampling date (excluding seedlings), and the mean number of all individuals per sampling date (including seedlings). For each of the three measures, the species differed markedly in their abundance. Moreover, most of the species displayed low levels of abundance; few had intermediate or high abundance. When the three measures of abundance were compared to each other, there was a moderate level of agreement concerning which species were common and which were rare. However, when individual species were examined closely, some important differences between the three measures emerged. Thus, it is important to precisely define what is meant by "abundance".