Last week, the United Nations added 18 sites around the globe to its list of biosphere reserves, bringing the total number of sites so designated under its Man and the Biosphere Program to 581.

Most of us are probably more familiar with another U.N. collection: World Heritage Sites, which identify “universally” valued spots for conservation and awareness efforts. Indeed, some particularly special locales receive both designations.

But the purpose of biosphere reserves transcends basic conservation. The reserves are intended to showcase ways that humans can reconcile our needs and activities with those of native flora and fauna. They highlight unique and innovative strategies that are working — right now.

Although the U.N.’s Programme has existed for more than 30 years, in some ways, these conservation ideas — merging man with nature, rather than separating man from it — are really just catching on.

For decades, we’ve tried strategies like the infamous “fortress conservation,” in which a parcel of land is hermetically sealed off from human access. In some cases, this has smacked of neocolonialism, when the big, bad NGO swoops in to buy up land and intimidate or bribe indigenous people into exile.

In the United States, when an endangered species is critically threatened, we’re also willing to cordon off plots of land, post signage and bar entry. And in our national parks, where we want people to enjoy and experience wild nature, we must still somehow quantify — and maintain —“wildness.” In Maine’s crowded Acadia National Park, for example, no backcountry hiking is permitted because there simply isn’t enoughbackcountry to go around.

Most of us would probably agree that some — if not most — closures are for the best. Amid the extremes of the United States-landscape matrix, our preserves stand in stark contrast to the great homogeneity of corn and soy fields, for example. And because conventional wisdom dictates that planetary biodiversity is best preserved by setting land aside, we have hard goals, like the Convention on Biological Diversity’s aim to protect 17 percent of terrestrial systems and 10 percent of seascapes.

Simultaneously, our planet faces pressures from a growing human population with shrinking resources. As our numbers swell and our oil-supported capacity for intensive crop production dwindles, we’ll doubtless press more land into agricultural service. Could you look poverty in the eye and demand its land for pristine rainforest? Could you look hunger in the eye and close its coral reef for biodiversity protection? I couldn’t.

If we could meet our conservation area goals, though,would that be enough? A decade ago, Ana Rodrigues and Kevin Gaston reviewed a score of studies on the land area needed to meet conservation goals. Their work, published in Ecology Letters in 2001, found that areal requirements could skyrocket up to 66 percent in some systems. If getting a sixth of an ecosystem into protection is unlikely, two thirds is probably impossible.

Since we’re not going to secure everything in the fortress, what else can we do?

Time to remind ourselves that scarcely any part of the planet exists without human modification. In fact, some of our most iconic landscapes were maintained by human activity. The eastern North American Great Plains, for example, required periodic burning by Native Americans to retain their “native” grass cover. And humans evolved in Africa, where we’ve spent millennia alongside “wildlife.”

So where’s the boundary between “us” and “nature,” between “wilderness” and “human-modified?” The extremes are obvious: compare a distant Pacific atoll to an effluent-packed harbor. Contrast the drones of pumps in Prudhoe Bay with the deep silence of an aurora-lit tundra.

But then compare a California rice paddy with a coastal salt marsh. Given that 90 percent of California’s wetlands have been lost to human activity, professor Chris Elphick of the University of Connecticut has found that rice farms can make up some of the missing ground. Indeed, these farms have proven exceptionally speciose: after some wildlife-friendly management changes, you can now spot about one in every five California bird species in a rice field.

And that’s where we turn to the U.N.’s Program and to research around the globe where humanity is still living— or learning to live — in step with nature.

We know that it’s possible to overload the natural system: intensive agriculture, otherworldly “minescapes” and other settings provide evidence of that. But we also know from our evolutionary history, from our recent past and from the evidence of our contemporary eyes, that humans are fundamentally a part of the balance of nature.

And so we come to the ultimate challenge: the environmental version of Buddhism’s Middle Way. If we want to protect biodiversity on a grand scale, we have to do more than protect it in discrete, firmly outlined patches. We have to do it in our own backyards by forgoing pesticides and growing native plants. We have to note which species require human absence, which tolerate some degree of disturbance and which thrive in our presence. And we have to create and maintain a patchwork landscape allowing for these differences, while still providing for human needs.

So gather up your ones and zeros, because the future of conservation is out in that landscape matrix.