Allelopathic effects of ash juniper (Juniperus ashei) on little bluestem (Schizachyrium scoparium), side oats grama (Bouteloua curtipendula), and cedar sedge (Carex planostachys).
Young, Gwen*,1, Bush, Janis1, 1 University of Texas at San Antonio, San Antonio, TX
ABSTRACT- Juniperus ashei Buchholz is native to the limestone slopes of Central Texas. In the past, naturally occurring range fires have managed populations and helped to contain ash juniper to slopes and rocky areas with little fine fuel. Ash juniper is moving out of its native range and is rapidly encroaching into neighboring landscapes. Grass and forb production and species diversity are greatly reduced under the canopy of ash juniper, possibly due to competition for water, nutrients and sunlight. Allelopathy, defined by Rice as any direct or indirect beneficial or harmful effect of one plant on another through release of chemicals into the environment, has also been suggested. We tested Juniperus ashei leaf and litter samples for allelopathic effect under laboratory germination studies of the native graminoid species little bluestem (Schizachyrium scoparium), side oats grama (Bouteloua curtipendula) and cedar sedge (Carex planostachys). A modified ′sandwich method′ which places J. ashei leaf and litter samples within two layers of agar (0.5% w/v) was used. The highest germination of side-oats grama (41%) occurred in the control, which was not significantly different from litter treatment (30%). The lowest germination (16%) occurred in the leaf treatment which was significantly different than the control. Little bluestem germination was low (<6%) for all treatments. The average shoot length of cedar sedge was not significantly different among the treatments. There is a suggestion that compounds from the leaves of J. ashei inhibit the germination of side oats grama. Cedar sedge, a species known to grow with ash juniper, appears to be uninhibited by juniper leaf or litter.
Key words: allelopathy, Juniperus ashei, grasslands
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