Gt. Golm et al., LIFE EXPECTANCY IN A TULSA CEMETERY - GROWTH AND POPULATION-STRUCTUREOF THE LICHEN XANTHOPARMELIA-CUMBERLANDIA, The American midland naturalist, 129(2), 1993, pp. 373-383
The demographics of a population of the foliose lichen Xanthoparmelia
cumberlandia growing on gravestones in a Tulsa cemetery are presented.
Because of the regular layout of granitic gravestones, the cemetery a
cted as a mechanism for generating experimental replicates and as a co
ntrol for habitat variability. The lichen population was multi-modal,
based on age classes. Thalli within each age class approximated a norm
al distribution of size. Age classes were separated by several years.
Growth rates of thalli within age classes were independent of size, bu
t growth was dependent on age class. Thallus growth varied among the m
onths, and was correlated with precipitation but uncorrelated with tem
perature. Mortality rate was greatest in age class III, and lowest in
class I (I youngest-III oldest thalli). A population model of the spec
ies showed that recruitment has been sporadic, yet highly successful w
hen it did occur. The model depicts growth rates as independent of siz
e within, but not among, the three age classes.