Aggregating fields of annual crops to form larger-scale monocultures can suppress dispersal-limited herbivores

Collin B. Edwards, Jay A. Rosenheim, Moran Segoli

Research output: Contribution to journalArticlepeer-review

3 Scopus citations

Abstract

An important part of landscape ecology is determining how the arrangement (aggregation or fragmentation) of patches in space influences the population dynamics of foraging organisms. One hypothesis in agricultural ecology is that fine-grain spatial heterogeneity in cropping (many small agricultural fields) should provide better pest control than coarse-grain heterogeneity (few large agricultural fields); this hypothesis has been proposed as an explanation for the increased pest abundance associated with agricultural intensification. However, empirical studies have found mixed support for this hypothesis, and some, surprisingly, demonstrate a strong decrease in pest abundance with increased crop aggregation. We developed a spatially explicit simulation model of pest movement across an agricultural landscape to uncover basic processes that could reduce pest abundance in landscapes with fewer, larger fields. This model focuses on herbivore movement and does not include predation effects or other biological interactions. We found that field aggregation in the model led to severely reduced pest densities and further discovered that this relationship was due to an increased distance between fields and a decreased “target area” in more aggregated landscapes. The features that create a negative relationship between aggregation and pest densities rely on crop rotation and limited dispersal capabilities of the pests. These findings help to explain seemingly counter-intuitive empirical studies and provide an expectation for when field aggregation may reduce pest populations in agro-ecosystems.

Original languageEnglish
Pages (from-to)321-331
Number of pages11
JournalTheoretical Ecology
Volume11
Issue number3
DOIs
StatePublished - 1 Sep 2018
Externally publishedYes

Keywords

  • Agricultural intensification
  • Agroecology
  • Dispersal
  • Habitat fragmentation
  • Land use
  • Simulation model

ASJC Scopus subject areas

  • Ecology
  • Ecological Modeling

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