LAGOMORPHS AND THE DISPERSAL OF SEEDS INTO COMMUNITIES DOMINATED BY EXOTIC ANNUAL WEEDS

Large areas of western rangeland are presently dominated by alien annual weeds such as Bromus tectorum (cheatgrass). These communities resist succession to perennial communities primarily because the annuals are competitively superior to establishing perennial seedlings and they promote fires that f...

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Bibliographic Details
Published in:The Great Basin naturalist 1997-07, Vol.57 (3), p.253-258
Main Authors: Schupp, Eugene W., Heaton, Hoyt J., Gómez, José M.
Format: Article
Language:English
Subjects:
Annual grasslands
Annual weeds
Applied ecology
Hares
Juniperus osteosperma
Lepus
Rangeland ecology
Seed dispersal
Seeds
Shrubs
Sylvilagus
Woodland grasslands
Woodlands
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Summary:Large areas of western rangeland are presently dominated by alien annual weeds such as Bromus tectorum (cheatgrass). These communities resist succession to perennial communities primarily because the annuals are competitively superior to establishing perennial seedlings and they promote fires that favor weeds over perennials. Succession may be further slowed, however, by low rates of seed dispersal into annual grasslands. We investigated the role of lagomorphs (Sylvilagus nuttallii, Nuttall's cottontail; S. audubonii, desert cottontail; and Lepus californicus, black-tailed jackrabbit) in seed dispersal across an ecotone between an open juniper woodland and an annual grassland. We collected pellets along five 100 x 2-m transects parallel to the ecotone: 50 m into woodland, border, and 20 m, 50 m, and 100 m into grassland. We searched pellets for juniper seeds visually and for any other species through germination from crushed pellets after cold, moist stratification. Pellets were not evenly distributed across transects, but there was no trend with respect to position of transect. Juniperus osteosperma (Utah juniper) was the most abundant seed. Both the number of juniper seeds and the proportion of pellets with juniper seeds decreased steadily from a high in woodland to absence at 100 m into grassland. Only 2 dicot seedlings emerged from pellets, 1 Salsola pestifer and 1 unknown that died prior to identification. Consequently, there was little seed movement into the grassland; 72% of all seeds were collected from either woodland or border transects. Lagomorphs apparently do not effectively replenish the native perennial seed pool of cheatgrass-dominated disturbances at Dugway.
ISSN:0017-3614