y good night's sleep after a long day out in the field is broken too early by Klemens telling me to get up and see the sun strike the east-facing ridge of the Palisades across the Hudson from his Dobbs Ferry, New York, apartment. "This is the most extraordinary light of the day, and it lasts for only a minute," he tells me.

The Palisades have experienced this exact minute of light for thousands of years. It's my first time and I am impressed. There is no fade-in or fade-out. The glow, a yellow corona on the ridge above the sheer cliff face, appears suddenly and then vanishes. We pack up our gear for the trip back to the pools of Dover.

During his time at the Metropolitan Conservation Alliance, one of the most difficult issues Klemens has encountered is that of "takings" -- the notion that limiting a property owner's use of the land requires the town, county, or state to provide compensation.

"This is the number-one sticking point at the local level. Local decision makers have been beat over the head by lawyers into thinking that any kind of public regulation, any kind of public interest, any kind of public concern, is not protected and is in fact a taking. And that is bullshit.

"What I urge local leaders to do is talk more about the givings than the takings. When land improves in value it's not just because of your investment. The fact that I bought a piece of property in Rye that's worth more than it was when I bought it has nothing to do with my investment in that land. It has all to do with the standards of that community that have made that investment grow and prosper. And therefore I am beholden directly to that community."

His other concern is that haphazard development will create a checkerboard of disconnected open space.

"You can't take a 100-acre parcel, say you're developing only 50 percent of it, and not have any open space connect to any other open space. That's one of the big problems with the way development has been done. The decisions are made one at a time without regard for how they assemble on the landscape."

Biodiversity can't be protected one vernal pool at a time. And yet, as Klemens sees it, present zoning regulations and land-use practices, such as those that require large lots for each home, prevent creative preservation schemes and further promote sprawl.

And sprawl, says Klemens, is "an insidious threat not only to the environment and ecosystems but also to our societal fabric."