Diurnal gross photosynthetic patterns and potential seasonal CO 2 assimilation in Cladonia stellaris and Cladonia rangiferina

• Published in: Canadian Journal of Botany
• Main Authors: Moser, Thomas J., Nash III, Thomas H., Link, Steven O.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 1983
• Subjects: Cladonia rangiferina; Alaska
• Online Access: http://dx.doi.org/10.1139/b83-073; http://www.nrcresearchpress.com/doi/pdf/10.1139/b83-073

The daily, in situ gross photosynthetic patterns of Cladonia stellaris (Opiz.) Pouz. & Vězda. and Cladonia rangiferina (L.) Wigg. were monitored during portions of the 1977, 1978, and 1979 growing seasons at Anaktuvuk Pass, Alaska. Photosynthetic activity in both species closely paralleled atmospheric moisture status, where peak photosynthetic rates were attained during or following sporadic summer rain. In addition, thallus absorption of moisture during extended periods of high atmospheric water vapor content gave rise to short periods of minimal photosynthetic activity. During late evening and early morning hours moistened thalli exhibited minimal or no photosynthetic activity, coinciding with consistent attenuation in solar radiation during these periods. Photosynthetic activity was not homogeneous throughout the thallus. The greatest activity occurred in the apical regions and decreased progressively into the basal regions. The apical 10-mm regions of C. stellaris and C. rangiferina thalli accounted for approximately 50% of their photosynthetic capabilities. The potential gross CO 2 assimilation of the apical 10-mm regions over 72 days of the 1978 growing season was estimated at approximately 35 g CO 2 ∙m −2 and 16 g CO 2 ∙m −2 for C. stellaris and C. rangiferina, respectively.