Going with the grain: Scalar conservation easement dataset comparison

Context: Private land conservation maintains global biodiversity while securing areas for biome shifts. Conservation easements (CEs) are the dominant form in both the US and increasingly, globally. Objectives: We illustrate the differences in the National Conservation Easement Database (NCED) and a fine-scale curated collection of CEs, the Granular Conservation Easement Datasets (GCED), which fills an imperative gap in the CE literature. We assessed each dataset’s utility for different research objectives. Methods: The GCED represents a comprehensive baseline of the CEs placed between 1997 and 2008/2009 in twelve counties in six US states. We empirically compared GCED and NCED spatial geometries and related attributional data with qualitative and quantitative analyses. Results: NCED completeness varies geographically and categorically over time, lacking historical information about CE amendments. GCED comparison with the NCED subset with a year of CE establishment revealed a consistently higher CE count in the majority of GCED counties. CE spatial configurations also diverged between the GCED and the NCED. Spatial statistical analysis outcomes differed; for each dataset, CEs are generally clustering (Ripley’s K) but Global Moran’s I and Average Nearest Neighbor results diverged to varying degrees. Conclusions: The NCED creates a double-edged sword for researchers as the only nationally and publicly accessible compilation of CE data with evident omission bias. Landscape management and planning studies rely on the NCED but its incompleteness hinders its utility as a tool for CE tracking, oversight, planning, and research. Broad-scale geographic coverage and fine-scale accuracy are a tradeoff; future scholarship should understand the shortcomings of a particular dataset at a particular scale.