CALORIMETRIC EVIDENCE FOR SITE-ADAPTED BIOSYNTHETIC METABOLISM IN COAST REDWOOD (SEQUOIA SEMPERVIRENS)

Uses of recently available calorimetry technology are explored for measurement of metabolic activity - temperature relations in coast redwoods (Sequoia sempevirens (D. Don) Endl.). These redwoods were collected from different parts of the native range and grown in a common-garden plantation. Analysis of metabolic activity from 10 to 55 degrees C was used to examine site adaptedness of respiratory metabolism in 16 representative clones of coast redwood. Apparent activation energies changed markedly over the range 12-52 degrees C, but the patterns of change were similar for clones from five geographical regions and thus appear to be general for the species. However, high-temperature stability, the temperature of peak activity, and the peak metabolic heat rate differed substantially among samples from the five regions. Additional variability in high temperature stability and the temperature of peak activity was measured between trees from the same stands within regions. We suggest that the observed regional and clonal variations in high-temperature stability, the temperature of peak activity, and the peak metabolic heat rate are biologically meaningful. These may be used both to understand the adaptive architecture of coast redwood and to select clones likely to be adapted to particular sites or defined ranges of sites.