Juniper Extract and Deficient Aeration Effects on Germination of Six Range Species

Abstract

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Understory species response to Utah juniper litter

“…These results indicate that allelopathic effects of Utah juniper are species specific. Similar findings were reported for Rocky Mountain juniper by Peterson (1972) and for 1-seed juniper by Lavin et al (1968).…”

“…Hypotheses to explain how junipers are able to dominate a site include: 1) increased canopy cover which creates shading (Schott and Pieper 1985) and intercepts precipitation (Skau 1964, Gifford 1970, 2) deep litter accumulation (Jameson 1966) 3) allelopathy (Lavin et al 1968, Peterson 1972 changes in the soil nutrient composition (Doescher et al 1987, Tiedemann 1987, and 5) competition for soil moisture (Miller et al 1987, Breshears et al 1997 Litter affects the understory either due to its depth (Everett and Koniak 1981) or to allelopathy (Lavin et al 1968, Jameson 1970 Johnsen (1962) demonstrated that a significant reduction occurred in blue grama emergence with as little as 2.5 cm of litter. It has been reported that juniper litter may be allelopathic (Lavin et al 1968, Peterson 1972. Allelopathy is defined "...as any direct or indirect harmful effect of one plant on another through production of chemical compounds that escape into the environment" (Rice 1984).…”

“…) produced both water soluble and volatile inhibitors that reduced germination of several herbaceous species. Lavin et al (1968) reported that allelopathy in Utah juniper was species specific. Johnsen (1962) found that one seed juniper extracts did not significantly reduce blue grama germination.…”

“…The majority of allelopathy studies (Jameson 1961, Lavin et al 1968, Peterson 1972 have tested leachates made from fresh foliage. It is possible that the negative effects observed in those studies Litter depth was found to have a more profound effect on seedling emergence than did leachates.…”

Germination and establishment of fourwing saltbush in the southwest /

“…Germination in 72 hours was significantly reduced when oxygen was held at slightly less than 5 percent (Lavin et al 1968).…”