Abstract: Ecological data frequently exhibit spatial autocorrelation, whereby geographically proximate sampling units are more similar in species distributions, community composition, or environmental attributes than expected by chance. Spatial Autoregressive Models (SARs) address this issue by explicitly incorporating spatial dependence. However, disentangling the relative contributions of spatial structure and ecological predictors remains challenging, particularly in the presence of multicollinearity. The spatialreg.hp R package extends the concept of average shared variance (ASV) to SARs, enabling the decomposition of total model R² into unique and shared contributions of spatial and non-spatial predictors. The package calculates individual R² values for spatial effects and environmental variables that sum exactly to the total model R², thereby providing a new measure of predictor importance. We illustrate the package using case studies based on classic spatial datasets. The spatialreg.hp package offers ecologists and geographers a new framework for quantifying the interplay between spatial processes and environmental drivers in ecological modeling.

Key words: Average shared variance, Hierarchical portioning, R package, spatial autocorrelation, Variation partitioning