VARIATION IN CHEMICAL AND PHYSICAL-PROPERTIES DURING LEAF DEVELOPMENTIN CALIFORNIA BAY TREE (UMBELLULARIA-CALIFORNICA) - PREDICTIONS REGARDING PALATABILITY FOR DEER

Changes in several chemical and physical characteristics of California Bay Tree, Umbellularia californica, foliage in both new growth and ma ture leaves were measured from the spring flush (April) until bud set and dormancy in autumn (October). Five sequential leaf developmental s tages were described, with leaves passing through Stages One to Four d uring a growing season, and remaining in Stage Five after winter dorma ncy (i.e. second year of growth). Monoterpenoid total yield (mg all mo noterpenoids/g LDW) increased from very low levels in Stage One to hig h levels in Stages Four and Five. Monoterpenoid composition (% of tota l yield by individual compounds) was highly variable among the develop mental stages; however, concentrations of the four most abundant compo unds, sabinene, 1,8 cineole, pino-carvone and umbellulone, all increas ed from Stages One to Four. Over winter, the concentrations (mg indivi dual compound/g LDW) of pinocarvone dropped and umbellulone rose drama tically in leaf Stage Five, while the total yield did not change. Tota l nitrogen content decreased from Stage One to Stage Five. Total nonst ructural carbohydrate did not vary statistically among the leaf develo pmental stages. Leaf specific weight, per cent moisture, and leaf toug hness also increased with leaf development. From these results we pred ict U. californica foliage palatability for Blacktailed Deer. Copyrigh t (C) 1996 Elsevier Science Ltd