Can Carbon Sequestration be 'Leased'?

f you plant trees to earn carbon credits under the Kyoto Protocol, you'll earn temporary Certified Emission Reduction (tCER) certificates, which expire after a few years to reflect the perceived fragility of carbon captured in plants. They've proven unpopular with buyers, and sell for a fraction of the price of normal CERs. The United States, however, may use five-year term offsets for land-use offsets under its cap-and-trade scheme, and sellers say lower prices are fine with them. Here's why.
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So, what can we expect from the US as we move towards Copenhagen? The climate-change science certainly isn't changing, and it's clear that a weaker climate bill would not be in anyone's best interest.

[How much money should be blown paying people not to cut down trees that they wouldn't have cut down anyway, in order to cool the planet [when this doesn't really cool the planet], when a warmer planet would probably be more desirable?] - Environmental Capital - WSJ

The problem: How can you tell when a forest is left alone specifically to fight climate change—in which case that inaction is worth billions of dollars–and when it is just left alone?