By John A. Wiens

Picture a nature preserve — a “last great place,” or even just a pretty good place.

Conservationists identify these places and prioritize them through rigorous planning protocols. But how can we ensure that these places will retain their conservation value over the long haul? Or even that they will continue to be the right places? The world is dynamic, after all.

Climate change and its ecological and societal impacts are finally receiving widespread attention. But a related and arguably more urgent issue still needs more focus: land use and land-use change.

The Driver Behind Habitat Loss 

Human land uses are the major cause of habitat loss throughout the world, and rates of land-use change are accelerating. Examples are legion: 

• Some 4.5 million hectares of wetlands disappeared in the United States between the 1950s and 1970s, chiefly through conversion to agriculture.
   
• In Western Australia, 93 percent of native vegetation was converted to agriculture by the early 1960's, leaving only scattered woodland remnants.
   
• In semiarid regions of New Mexico and Idaho, grazing and fire have produced irreversible changes in land cover from grassland to shrubland (or vice versa).

And the list goes on.  

'Natural' is a Relative Term  

Of course it is naïve to think that only recent land uses affect the integrity of the habitats we strive to conserve:

• Seemingly "natural" tropical forest in Puerto Rico bears the imprints of agricultural land uses centuries ago.
   
• And plant communities in some French forests still reflect a brief period of agricultural land use during the Roman occupation in A.D. 50-250. 

What we see today contains the legacies of past land uses. 'Natural' is a relative term.

Understanding the effects of the past land uses on natural habitats and biodiversity is useful. But what is really needed is knowledge that can help us anticipate and adjust for future land-use changes.

Some Rude Surprises Ahead

This knowledge requires an understanding of the underlying socioeconomic and political forces that contribute to land-use change. For example: 

• In Eastern Europe, the breakup of the former Soviet Union led almost immediately to the replacement of collective farms by smaller, more diverse single-family farms, which enhanced the heterogeneity and wildlife value of local landscapes. 

• The recent expansion of soybean agriculture in parts of Brazil was fostered in large part by global economics and advances in agricultural technology. 
   
• The current rush to embrace biofuels as energy sources is causing massive cropland conversions in the central United States and a cascading array of ripple effects as corn prices escalate.

In the future, demographic changes such as the retirement of the baby-boom generation, technological advances such as telecommuting and economic expansion in developing countries (witness China!) will all contribute to major shifts in land uses.

Globalization means that land uses in one part of the world are increasingly influenced by factors elsewhere. And the abrupt thresholds in how ecologies respond to land-use change mean that we are likely in for some rude surprises. 

The Thorny Localness of Land-Use Issues

A 2002 top story on the NASA Web site bore this headline: “Landcover Changes May Rival Greenhouse Gases as Cause of Climate Change.” Clearly, consideration of climate change and land-use change in isolation from the other provides only a partial picture. 
 

How we deal with the two issues, however, is likely to be quite different. Whereas considerations of climate change tend to start at the global level and work down, land use is essentially local, and the effects of land use and land-use change amplify upwards to broader scales.

Consequently, while there may be some hope of dealing with climate change through broad multinational policy accords, land use is likely to remain immersed in a morass of local and idiosyncratic policies and politics, particularly in the United States. 

What Can We Do?

Actually, quite a lot. Many conservation strategies are aimed at influencing land uses or lessening their impacts on biodiversity, so there is a strong foundation of experience on which to build. 

We could bolster some of this experience by using imagery to assess the form and magnitude of land-use changes surrounding protected areas since they were placed under conservation protection. Have they become islands? Have the connections across the landscape disappeared?

But we need also to couple such assessments with analyses of the potential consequences of different scenarios of future land-use changes. We need to develop ways of assessing “conservation futures.”

So what’s the bottom line?  

• If we don't look to the future, we probably won't be very effective in protecting our present conservation investments or investing wisely. 
   
• Climate change and land-use will affect these investments at multiple scales.
   
• We are moving to consider climate-change impacts much more aggressively; unless we do the same for land-use change, success at dealing with climate change will be illusory .
   
• Most of our attention is being given to protected areas.  But we must also recognize that the matrix of unprotected lands — the places where people live and work — can contribute to the goal of preserving biodiversity.

Land-use change will compromise conservation planning efforts if we ignore it or just pay it lip service.  Now is the time to start planning for our conservation future.  

This essay is adapted from the original version, which was published in the Bulletin of the British Ecological Society.

 
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Nature picture credits (left to right): © Scott Warren (Planted forests bordering the Sao Francsico Verdadeiro River, Parana state, Brazil); © Mark Godfrey/TNC (John Wiens)