MEASUREMENT OF AGE AND GROWTH RATE IN THE CRUSTOSE SAXICOLOUS LICHEN CALOPLACA TRACHYPHYLLAUSING14C ACCELERATOR MASS SPECTROMETRY

: Sections of the crustose saxicolous lichen, Caloplaca trachyphylla, were dated using14C accelerator mass spectrometry (AMS). The data show a strong linear dependence of radial position on time (r=0·993), suggesting a constant radial growth rate. This specimen had averaged a marginal growth rate of 1·48 mm/year. Extrapolation of the growth curve yields a thallus age of 20 years. These data demonstrate the feasibility of using AMS technology to precisely date lichen tissues and determine growth rates of lichen thalli.