Mean monoterpene content of singleleaf pinyon (Pinus monophylla [Torr.] Frem.) litter from stands growing on two soil series was 340 ± 310 ug/g air dry weight (adw). Individual monoterpene hydrocarbons suggested as potential allelopathic compounds occur in extremely small amounts, 0.5–1.10 ug/g adw. Mineral soils contained 50 times less total terpene, 6.6 ug/g ± 4.8 adw, than the litter immediately above. Results suggest that allelopathic effects would more likely occur in litter than mineral soil. These findings are substantiated by previous reports of decreased emergence and growth of herbaceous species in pinyon litter but not mineral soil.
Wilt, F. Martin; Miller, Glenn C.; and Everett, Richard L.
"Monoterpene concentrations in litter and soil of singleleaf pinyon woodlands of the western Great Basin,"
Great Basin Naturalist: Vol. 48
, Article 11.
Available at: http://scholarsarchive.byu.edu/gbn/vol48/iss2/11