title: Enrichment scale determines herbivore control of primary producers.
abstract: Anthropogenic nutrient enrichment stimulates primary production and threatens natural communities worldwide. Herbivores may counteract deleterious effects of enrichment by increasing their consumption of primary producers. However, field tests of herbivore control are often done by adding nutrients at small (e.g., sub-meter) scales, while enrichment in real systems often occurs at much larger scales (e.g., kilometers). Therefore, experimental results may be driven by processes that are not relevant at larger scales. Using a mathematical model, we show that herbivores can control primary producer biomass in experiments by concentrating their foraging in small enriched plots; however, at larger, realistic scales, the same mechanism may not lead to herbivore control of primary producers. Instead, other demographic mechanisms are required, but these are not examined in most field studies (and may not operate in many systems). This mismatch between experiments and natural processes suggests that many ecosystems may be less resilient to degradation via enrichment than previously believed.
authors.affiliation: Department of Biology, University of Florida, 220 Bartram Hall, Gainesville, FL, 32611-8525, USA. m.gil@ufl.edu.
authors.forename: Michael A
authors.initials: MA
authors.lastname: Gil
authors.affiliation: Department of Biology, University of Florida, 220 Bartram Hall, Gainesville, FL, 32611-8525, USA.
authors.forename: Jing
authors.initials: J
authors.lastname: Jiao
authors.affiliation: Department of Biology, University of Florida, 220 Bartram Hall, Gainesville, FL, 32611-8525, USA.|Odum School of Ecology, University of Georgia, 140 East Green Street, Athens, GA, 30602-2202, USA.
authors.forename: Craig W
authors.initials: CW
authors.lastname: Osenberg
mesh_terms: D000818:Animals; D018533:Biomass; D017753:Ecosystem; D005068:Eutrophication; D020387:Food Chain; D060434:Herbivory; D008954:Models, Biological; D010944:Plants
keywords: Consumer–resource dynamics; Ecological resilience; Eutrophication; Experimental bias; Ideal free distribution; Top-down versus bottom-up