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Simulating pesticide impacts on horned larks: a study in scaling from fields and flocks to populations and landscapes
Citation:
Dishman, D. AND N. Schumaker. Simulating pesticide impacts on horned larks: a study in scaling from fields and flocks to populations and landscapes. International Association for Landscape Ecology, Portland, OR, July 05 - 10, 2015.
Impact/Purpose:
Efforts to protect threatened and endangered species impacted by pesticides will be improved through the application of the novel research methods described here. We report on the use of modern computer simulation tools to study the horned lark’s response to pesticide applications, and the efficacy of mitigation strategies employed to protect the species.
Description:
Balancing the potential ecological impacts of anthropogenic stressors with the need to optimize food production, as in the case of agricultural pesticide use, creates enormous practical challenges for regulators. Concerns that compounds are impacting legally protected species are creating a need for regulatory decisions, traditionally based on individual-organism scale responses to exposure in controlled settings, to now account for population-level endpoints. Similarly, it has become increasingly clear that pesticides and multiple other natural and anthropogenic stressors interact in landscape settings, and that these interactions cannot be assumed to be simply additive. Finally, huge numbers of threatened and endangered plants and animals are potentially being affected, and this is creating a need for assessment tools that are biologically realistic, but also parsimonious and quick to develop and apply. Here, we discuss the design and application of a multi-stressor, spatially-explicit IBM (individual-based model) that can relate changes in disturbance regimes at local scales to population trends at landscape scales. Our target species is the endangered Streaked Horned Lark (Eremophila alpestris strigata), and our study region is Oregon’s Willamette Valley, an area dominated by agriculture that also includes a network of natural areas and wildlife refuges. We use the horned lark system to illustrate how pesticide impacts to a wildlife population can be disentangled from other dynamic disturbance regimes, but also discuss how our approach can be generalized to address a range of species-landscape-stressor systems, with the eventual goal of producing population-scale rapid assessment tools.