Josh Eagle (South Carolina) has posted Notional Generosity, 35 Harv. Envtl. L. Rev. ___ (2011), on SSRN.  Here is the abstract:

This article explores a phenomenon that might be called “gift-form generosity”: people earning similar amounts of income are more willing to part with a dollar’s worth of one kind of property than another. Among all income groups, the form of property with which charitable donors are most willing to part is the “conservation easement.” Data show, for example, that the average charitable easement donation is more than 100 times greater in value than the total, annual charitable contribution made by the average American taxpayer. Why are donors so willing to part with conservation easements? The answer may lie in donors’ ability to engage in what I call “donative arbitrage,” that is, the opportunity to profit, in tax-benefit terms, from the difference between the donor’s subjective valuation of the property and the value a hypothetical “willing buyer” would pay for it. To the extent that this hypothesis is correct, donors may in many cases be willing to sell their easements for less than the amount they currently receive as a tax benefit. Overpaying for conservation easements reduces the amount of public money that would otherwise be available for much needed conservation on private land. Allowing deductions for easement donations also creates individual incentives that are opposite of those that would produce optimal results. Specifically, landowners who most prefer to keep their land in its current condition (and who would thus give up very little in agreeing to land-use restrictions) will be the most likely to donate conservation easements. On the other hand, because similar restrictions would be expensive to them, landowners who are most interested in developing their property will be the least likely to donate. Thus, easement subsidies are spent protecting the land that is least in need of the protection afforded by easements. The article concludes by suggesting several ways that Congress might change the law so as to improve the efficiency of conservation easement subsidies.