A grazing model for simulating the impact of historical land management decisions in sensitive landscapes: Model design and validation

Abstract

This paper reports the construction and testing of a historical environmental simulation model, Búmodel (bú: Icelandic -farm estate or enterprise). The model permits the investigation of historical grazing management under variable environmental conditions in Iceland through the prediction of spatial and temporal patterns of vegetation biomass and utilisation. Input parameters of the model are environmental, livestock and management variables from historical and archaeological sources. Process sub-models were constructed using contemporary Icelandic data. Validation of the model was based on an independent, published grazing experiment and demonstrated that Búmodel-predicted utilisable biomass values and biomass intake values fall within G1 standard deviation of observed values.Búmodel provides a validated representation of linkages between environmental and management elements in a historical grazing system. It incorporates key issues of spatial and temporal scale, data quality, model validation and the inherent stochasticity of landscape change over historical periods. In doing so, it enables researchers interested in past landscapes to investigate the flexibility of the historical Icelandic grazing systems within the constraints of climate and vegetation cover, and provides a framework and methodology that can be applied to other historical extensive livestock-based agricultural systems. Access to the model is available at

Modeling Historic Rangeland Management and Grazing Pressures in Landscapes of Settlement

“…spreadsheet-based model that can be loosely coupled with ArcView GIS so that model inputs and outputs can be analyzed both statistically and in map form. The model has been validated using contemporary Icelandic research (Thomson and Simpson, 2006).…”

“…Model process submodels have been developed from contemporary agricultural research (Thomson and Simpson, 2006) from Icelandic sources. The maintenance requirements submodel predicts the nutritional requirements of the grazing livestock and the amount of vegetation that will be removed by grazing.…”

“…A larger cell size will give smaller scale patterns but will also reduce computation times. Búmodel is a stochastic (Thomson and Simpson, 2006). spreadsheet-based model that can be loosely coupled with ArcView GIS so that model inputs and outputs can be analyzed both statistically and in map form.…”

“…Búmodel is an environmental simulation model that predicts spatial and temporal patterns of vegetation biomass production and utilization (Thomson and Simpson, 2006). It has been developed for the purpose of investigating the interaction between farm management and vegetation degradation in Iceland in the premodern period (pre-1900 A.D.) (Fig.…”

Habitat Selection by Grazing Animals in Heterogeneous Environments: The Case of Hill Sheep In Western Ireland

“…Therefore, plant characteristics, along with grazer preferences, are often included in grazing management models that predict impacts of grazing management on flora and fauna (e.g. Thomson and Simpson 2006;Macaulay Institute 2009). Management models have become a powerful decision-making tool, synthesizing current knowledge and experience, and need sufficient data for validation (Wallis De Vries and van de Koppel 1998).…”