Geographic variation in the shoot productivity of bog shrubs and some environmental correlates

Abstract

The pattern of geographic variation in the annual shoot production of the three bog shrubs (leatherleaf (Chamaedaphne calyculata), bog laurel (Kalmia polifolia), and Labrador tea (Ledum groenlandicum) was examined using data collected at eight peatland sites along an 800-km latitudinal transect. Productivity varied significantly among sites, with L. groenlandicum exhibiting the greatest range of values (114–505 mg/shoot), followed by K. polifolia (83–341) and C. calyculata (73–241). This variation could be best interpreted by including both climatic and substrate variables in a multiple regression equation. The combination of three site variables (heat sum, depth to standing water, and water conductivity) accounted for between 63 and 86% of the observed variation in shoot productivity. Adding four other variables increased the percentage of variation explained to between 95 and 99%.