A recent paper in Science by Phalan et al. makes the case for establishing strict forest preserves and intensifying agricultural practices in the surrounding matrix.The paper compared two biodiversity-management strategies for agricultural landscapes:
1) Land sparing - set aside strict forest preserves while intensively farming the remaining land
2) Land sharing - adopt low-intensity, biodiversity-friendly farming across the landscape
The study correlated crop yields with densities of 341 bird and 260 tree species in India and Ghana across an agricultural intensity gradient (ranging from “diverse low-yielding mosaic agriculture to large-scale high-yielding monocultures”). They showed that, for a given amount of food production, most species (rare and common) would have higher populations under land sparing than land sharing.
There are caveats* to the conclusion that land-sparing is better for biodiversity. The authors point out that the conclusion depends on local context and may not hold for all species in all regions. The study did not discuss "how" to spare land in terms of building a network of forest preserves.
The agricultural landscape surrounding Montreal represents an opportunity to test this question. The image to the left highlights the fragmented forest patches (green) embedded within an agricultural matrix (yellow) and interspersed urban areas (gray). Perhaps this landscape could showcase an intermediate approach whereby biodiversity-friendly farming practices form the matrix around forest preserves and more intensive agriculture. In this model, eco-agricultural methods in the matrix and forest corridors would facilitate species dispersal among forest fragments to enhance biodiversity conservation, ecological functioning and ecosystem services across the forest network.
Certainly we need to apply cross-disciplinary biodiversity science that integrates ecological, economic, humanitarian and social interests to achieve the appropriate balance between land sharing and land sparing.
Reference: Phalan, B., Onial, M., Balmford, A., Green, R. E., Reconciling Food Production and Biodiversity Conservation: Land Sharing and Land Sparing Compared. 2011. Science. 333, 1289-1291.
*I haven't discussed implications of land sparing on food accessibility and security.