The heterogeneous effects of agricultural conservation easements on the loss of farmland to development in New England

Farmland near cities can provide diverse non-market benefits, such as recreational open space, landscape appeal, local food production, ecological habitat, and water regulation, which risk being underprovided by markets in the absence of intervention. The rapid loss of farmland to development has long been a concern of conservation non-profits and policymakers in the U.S. and globally, which has recently gained traction due to President Biden's decision to include farmlands in the federal goal to protect 30% of U.S. land by 2030. Agricultural conservation easements are a widespread policy tool to protect farmland from conversion to development in the long term. However, the extent to which these easements causally 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. Here we estimate the impacts of agricultural conservation easements on farmland loss at the parcel level at a large spatial scale and over a long time horizon. 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 quasi-experimental counterfactual estimation strategies to estimate the extent to which 3,959 farmland easements causally avoided conversion of cropland to development. Our results suggest that agricultural conservation easements have significantly reduced farmland loss to development. However, the overall magnitude of avoided rates of farmland loss on easements is very 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). A spatial allocation of agricultural easements towards more rapidly urbanizing counties (with farmland loss rates of up to 0.0281% of county area per annum) would increase the causal impacts of this instrument. Overall, our findings suggest that the spatial allocation of farmland easements has historically not prioritized the highest-threat locations where impacts would be most noticeable, indicating that allocation is driven by a variety of goals in addition to avoiding farmland loss.