Cooperative Fish and Wildlife Research Units Program: South Carolina
Education, Research and Technical Assistance for Managing Our Natural Resources

The spatial context of invasions is increasingly recognized as important for the success and efficiency of management actions. This information can be key for managing invasive grasses that threaten native ecosystems. While methods for quantifying invasive grass presence and abundance advance, few options have been explored in characterizing and comparing spatial patterns of extent and connectivity. We calculated landscape metrics and circuit-based centrality for invasive grasses using a weighted-average product (30m resolution) in the Great Basin, USA. We found variation among extent metrics (mean class and patch area, number of patches, largest patch index) and connectivity metrics (nearest neighbor, contiguity, aggregation index, centrality); most of the extent and connectivity metrics were not strongly correlated with dominant abundance class and so provided additional information at the sampled grid and local scales. We also illustrated how thresholding relevant metrics could be used to identify areas needing different management strategies, for example, where strategies could proactively protect uninvaded cores, disconnect fine fuel patches, or contain established invasions. The landscape metric approach can be applied across scales to spatially target patches locally, provide broader context within a single region, as well as to compare metrics and spatial variation in patterns among different regions.