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

Uses of recently available calorimetry technology are explored for mea surement of metabolic activity - temperature relations in coast redwoo ds (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 wa s used to examine site adaptedness of respiratory metabolism in 16 rep resentative clones of coast redwood. Apparent activation energies chan ged markedly over the range 12-52 degrees C, but the patterns of chang e were similar for clones from five geographical regions and thus appe ar to be general for the species. However, high-temperature stability, the temperature of peak activity, and the peak metabolic heat rate di ffered substantially among samples from the five regions. Additional v ariability in high temperature stability and the temperature of peak a ctivity 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 bot h to understand the adaptive architecture of coast redwood and to sele ct clones likely to be adapted to particular sites or defined ranges o f sites.