Michael Kaspari

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We maintained a factorial nitrogen (N), phosphorus (P), and potassium (K) addition experiment for 11 years in a humid lowland forest growing on a relatively fertile soil in Panama to evaluate potential nutrient limitation of tree growth rates, fine-litter production, and fine-root biomass. We replicated the eight factorial treatments four times using 32(More)
To explore the importance of 12 elements in litter production and decomposition, we fertilized 36 1600 m(2)-plots with combinations of N, P, K, or micronutrients (i.e. B, Ca, Cu, Fe, Mg, Mn, Mo, S, Zn) for 6 years in a lowland Panamanian forest. The 90% of litter falling as leaves and twigs failed to increase with fertilization, but reproductive litter(More)
Energy theory posits three processes that link local abundance of ectotherms to geographical gradients in temperature. A survey of 49 New World habitats found a two order of magnitude span in the abundance (nests m(-2)) of ground nesting ants (Formicidae). Abundance increased with net primary productivity (r2=0.55), a measure of the baseline supply of(More)
Sodium is an essential nutrient whose deposition in rainfall decreases with distance inland. The herbivores and microbial decomposers that feed on sodium-poor vegetation should be particularly constrained along gradients of decreasing sodium. We studied the use of sucrose and NaCl baits in 17 New World ant communities located 4-2757 km inland. Sodium use(More)
Numerous non-flying arboreal vertebrates use controlled descent (either parachuting or gliding sensu stricto) to avoid predation or to locate resources, and directional control during a jump or fall is thought to be an important stage in the evolution of flight. Here we show that workers of the neotropical ant Cephalotes atratus L. (Hymenoptera: Formicidae)(More)
The rules ants follow when selecting seeds are important both to theories of colony organization and to the shaping of their impact as harvesters. Two Costa Rican forests yielded the most diverse harvester ant assemblages yet studied (41 and 44±4 species). I assayed seed size preferences within and between species using milled barley. Seed size selection(More)
Although many taxa show a latitudinal gradient in richness, the relationship between latitude and species richness is often asymmetrical between the northern and southern hemispheres. Here we examine the latitudinal pattern of species richness across 1003 local ant assemblages. We find latitudinal asymmetry, with southern hemisphere sites being more diverse(More)
Large-scale (>100 m2/day) raids by tropical army ants have been linked to litter ant patchiness and diversity. In three Neotropical forests, densities of litter ants vary 10–20 fold at the 1-m2 scale. A survey of Barro Colorado Island. Panama, revealed that most army ant raids also occur on a 1-m2 scale with fronts ≤1 m wide. To explore the role that such(More)
Army ants form nomadic insect colonies whose chief food is other social insects. Here we compare the rate of army ant raids with the average density of their potential prey from 28 New World subtropical and tropical localities. We estimate that army ant raids occur at the rate of 1.22 m per day in tropical forests. Army ant raid rates increased with primary(More)