Driving through the Napa Valley last Saturday, the feeling crept over me once again. It's an uneasy, hemmed-in feeling that I often get while traversing the floor of this long, narrow, beautiful valley. Grapevines to the right. Grapevines to the left. Grapevines behind me. Grapevines in front of me.

Okay, I admit it. I felt claustrophobic.

And the reason I felt claustrophobic – other than an innate tendency in that direction – is because the Napa Valley, beautiful though it is, is what you might call a mono-landscape. It's natural, yes – but it's nature manipulated by human beings for a single economic purpose: the sale of wine. It's not a rural area. It's a factory and a theme park rolled into one. If this isn't always evident as you drive up Highway 29 or the Silverado Trail, it's pretty obvious when you enter a tasting room – and hear the constant ca-ching of the cash register.

This kind of a factory and theme park, of course, requires land – land to grow the grapes and land to provide the backdrop. So it's not surprising that the voters of Napa County have locked in a requirement making it very difficult to change how agricultural land is used. In 1990, the voters adopted Measure J – the original "SOAR" measure, which requires voter approval when changing the land use designation on agricultural land. In 2008, Napa voters will decide whether to renew Measure J.

In his brilliant book Nature's Metropolis, academic William Cronon came up with the term "second nature" to refer to landscapes like Napa Valley that appear natural but have, in fact, been altered by people for economic reasons. Because it appears natural, a farming or forestry area has sentimental appeal to people – residents and visitors alike – and this affects the politics of land use, which in turn affects the economics of the landscape being protected.

This is perhaps most obviously true in the Napa Valley, which has probably the most valuable agricultural land in the world. But it's also true in a place like Ventura County, where I live, which has adopted Napa's Measure J approach countywide. Except in Ventura's case, the SOAR initiatives were adopted over the objections of the farmers, rather than with their consent. (Click here for a brief history of SOAR-style urban growth boundaries.) In Ventura and elsewhere, residents voted to protect one economic landscape (agriculture) in order to prevent the creation of another economic landscape (urbanization) even though the people in the business they were protecting didn't want it.

Since agriculture is an economic landscape, however, that means that the landscape's owners – farmers or growers – can still manipulate it even if they don't urbanize it. Since the passage of the SOAR initiatives, for example, we here in Ventura County have seen significant changes to our agricultural landscape – even though we haven't seen much urbanization. Our iconic orchards are being pulled out and replaced with row crops. And some of our row crops are being replaced with greenhouses. The reason is simple: Having come to terms with the idea that they may never develop their property, agricultural landowners are focusing instead on squeezing every dollar they can out of agriculture.

The same is true in Napa – and the other emerging wine areas of the state – where there are constant battles over the proliferation of tasting rooms in supposedly rural areas, traffic on back roads, and the like. It's a reminder that the factory and the theme park don't always fit together well – at least not in the same mono-landscape.