Scale effects of vegetation on forager movement and seed harvesting by ants
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Authors: T. O. Crist, and J. A. Wiens
Date: 1994
Journal: Oikos
Volume: 69
Number: 1
Pages: 37-46
Summary of Methods: Crist and Wiens studied how seed harvesting by western harvester ants (Pogonomyrmex occidentalis) was different across spatial scales and organizational levels from individual ants to populations, and how vegetation structure affects foraging movements of individuals and resource use of colonies and populations. Lightly-grazed pastures with heterogeneous structure had the most seed removal on patches of bare ground. Areas in prairie dog (Cynomys ludovicianus) colonies had the least seeds removed, which is probably attributed to the presence of the harvester ant predator, the short-horned lizard (Phrynosoma douglassi), in these areas. Indian ricegrass (Oryzopsis hymenoides) and pepperweed (Lepidium densiflorum) comprised 91% of all seeds harvested, most taken from bare ground patches near ant nests. Seed removal was largely influenced by population level processes, including predation and grazing intensity.
Article Summary / Main Points: None
Vegetation Types:
MLRA Ecoregions:
Agrovoc Control Words: Riparian zones Rangelands Wildlife
Article Review Type: Refereed
Article Type: Experimental Research
Keywords: western harvester ant, pogonomyrmex occidentalis, prairie dog, cynomys ludovicianus, short-horned lizard, phrynosoma douglassi, indian ricegrass, oryzopsis hymenoides, pepperweed, lepidium densiflorum
Annotation: Seed-dish experiments and ant observations were recorded in 5-ha areas in each of three pastures with different grazing history. One moderately grazed pasture ("low grass") had a low grass canopy due to grazing and prairie dog disturbance. Another moderately grazed pasture ("medium grass") had a more continuous, complex canopy cover without prairie dog disturbance. A lightly grazed pasture ("shrub-grass") had heterogeneous vegetation with more shrub and cactus canopy cover in the grass.
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