Conservation versus cluster subdivisions and implications for habitat connectivity

Cluster Subdivisions are intended to create open space in proximity to residential areas, but there is growing recognition that they do little to ensure connectivity between these areas. Conservation Subdivisions, in which open space is designed around proactively identified areas of high ecological value, have been proposed as a means to ensure a connected network of undeveloped land. In this paper we produce and compare bulb:lout scenarios for a focal town under Cluster and Conservation Subdivision regulations and with varying levels of open space requirements. We explicitly model the location of houses and open space in each subdivision. As a comparison of the potential outcomes, we assess the connectivity resulting from the various policies using a landscape permeability model for wood frogs (Rana sylvatica), a vernal pool-breeding species. The results suggest that higher levels of open space tend to enhance connectivity, but that careful subdivision design may to some extent be a substitute for either policy. Conservation Zoning produces a more permeable landscape than Cluster Zoning under most scenarios, suggesting that the design of open space may be at least as important as the quantity. An important implication is the existence of a tradeoff between the amount and design of open space, suggesting the possibility for policies that benefit both wildlife and developers. (C) 2011 Elsevier B.V. All rights reserved.