LOSS OF MONOTERPENES FROM UMBELLULARIA-CALIFORNICA LEAF-LITTER

A litter bag experiment was conducted to study changes in foliar monot erpene yields (total, oxygenated monoterpenes, and monoterpene hydroca rbons) and per cent hydrocarbons in Umbellularia californica (Californ ia Bay Tree) leaf litter and to investigate how climate may influence this process. Monoterpene yields (mg g(-1) original leaf dry wt.), and per cent hydrocarbons (ratio of hydrocarbon yield/total monoterpene y ield) were not significantly different among green, yellow. and brown (newly fallen) foliage. Litter at moist sites absorbed water from rain significantly earlier in the season than that at dry sites and remain ed wetter than litter at dry sites throughout the collection period. D ecomposition (mass lost) was not significantly different at all study sites. Oxygenated monoterpenes were lost to a greater extent than hydr ocarbons. Total monoterpene yield decreased between 63% and 86% during the study period. Total monoterpene yields in litter at moist sites w ere significantly less than those at dry sites at the end of the study period. Most of the decrease in total monoterpene yield occurred duri ng the period of greatest rainfall. The per cent of monoterpene hydroc arbons was significantly greater at the end of the rainy season than a t the beginning and significantly greater at moist sites than dry site s. Loss of monoterpenes from litter was correlated with monoterpene wa ter solubility (r=0.82).