Population models provide a means to link population-level dynamics, species and habitat characteristics as well as information about stressors in a single approach. They are increasingly recognized as important tools in pesticide risk assessment, and were recently identified as essential for endangered species assessment in the U.S. However, few population models for this specific purpose have been developed to date. Developing such models in a systematic and transparent way would increase their applicability and credibility and reduce development efforts. A wide variety of population model applications and resources on modeling techniques, evaluation and documentation can be found in the literature, but guidance on model development is lacking.
Results/Conclusions
We present a systematic and transparent approach to developing population models. The guidance informs the model developer on necessary steps that consider the specific questions to be addressed by the model through four phases. In the first phase, the model developer systematically reviews the details of the model objectives. Data available for the modeled species and stressor(s) are compiled in table format during the second phase. Starting with a conceptual model of the species’ life history in the third phase, seven decision steps guide the model developer through decisions on what and how details should be represented in the model based on the model objectives and the data availability. Decision steps may need to be revisited iteratively during the third phase. In the fourth phase, the model developer compiles a summary of the conceptual model including the underlying assumptions. Uncertainties arising from data and model assumptions are also explicitly characterized. We provide an example decision guide for the development of population models of herbaceous plants applied in pesticide risk assessment. The adaptation of the approach to developing population models for other taxonomic groups and applications will be discussed.