Estimating the parcel-level impacts of agricultural conservation easements on farmland loss using satellite data in New England

The rapid loss of farmland to development has long been a concern of policymakers and conservation non-profits globally. In the United States, agricultural conservation easements are a widespread policy tool used to protect farmland from conversion to development in perpetuity. However, the extent to which these easements reduce farmland loss to development within their boundaries is rarely studied at the spatial scale at which easement adoption decisions are made: the individual parcel. Our case study from six New England states uses a rich dataset of 1.97 million parcels, novel estimates of annual parcel-level land cover change from 1988 to 2016, and a quasi-experimental research design to estimate the extent to which 3959 farmland easements avoided conversion of cropland to development. We examine and discuss the suitability of remote sensing data and quasi-experimental matching methods for impact assessments in this geographic and political context. Our empirical results suggest that agricultural conservation easements have reduced farmland loss to development. The magnitude of avoided farmland loss is small (0.0067% ± 0.0019% of parcel area per annum), largely because of a low background rate of farmland loss across New England (0.0027% of total area per annum). Our findings suggest that the spatial allocation of farmland easements has historically not prioritized the highest-threat locations where impacts would be most noticeable, as allocation is driven by a diverse range of goals in addition to avoiding farmland loss.