|KHALIL, NELLIE - NEW MEXICO STATE UNIV
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 9/1/2003
Publication Date: N/A
Technical Abstract: Limitations to grass seedling recruitment, including herbivory and abiotic causes of seedling mortality, are expected to differ across an shrub-grass ecotone. Grass seedlings at shrub dominated ends of the gradient will likely have higher rates of mortality due to herbivory (because of increased predator presence and increased seedling visibility) and overall mortality (due to harsher abiotic conditions).Black grama seedlings were placed across three replicate ecotones (each containing a shrub-dominated position, a midpoint, and grass-dominated position) and rates of herbivory and overall mortality were observed. Rodent, lagomorph, and grasshopper abundances were measured across the three ecotone positions. Rates of mortality due to herbivory and overall mortality were highest in the shrub position, followed by the midpoint position, and least in the grass position. Small animal abundance did not follow this pattern (rodents and lagomorph pellets were most prevalent in the midpoint position, while grasshoppers were most prevalent in the grass position). The shrub dominated position has the highest rate of overall mortality because of abiotic factors that create a harsh environment in shrub dominated areas. Increased visibility of grass seedlings to predators in the shrub position may cause the shrub position to have the highest rate of death due to herbivory.