By Matt Miller, senior science writer, The Nature Conservancy
Across the western United States, it’s a familiar conservationist’s lament: rangelands are disappearing at an alarming rate, lost in a sea of “for sale” signs and subdivisions.
But what do the data really say? What are the long-term trends in rangeland conversion? Are conservation easements and other land protection tools making a difference?
A new paper in the journal PLOS ONE by Dick Cameron, a lead scientist for The Nature Conservancy in California, and coauthors presents a comprehensive view of rangeland conversion — and just as importantly, the drivers of this conversion — on a large scale.
The result is a comprehensive look at landscape change. And it’s true: rangelands really are disappearing at an alarming rate.
What are the Losses?
Cameron and his coauthors used a dataset of land-use types to map rangeland conversion in California between 1984 and 2008. They classified the resulting land-use changes with aerial imagery to determine whether it was developed into homes, planted with crops or dedicated to other land uses.
Then they compared this loss against ranchland protection achieved by various conservation measures. They found a loss of more than 20,000 acres of rangeland per year to other uses within California, for a total loss of more than 480,000 acres.
Of the remaining rangeland, only 24 percent was protected against future conversions by conservation easement or fee ownership. About 38 percent had no protection at all.
Is It Just Homes on the Range?
Conservationists often cite residential and commercial development as key threats to rangeland development.
And indeed, researchers found this as a significant factor, accounting for 49 percent of the conversion.
More surprisingly, 40 percent of rangelands were lost to agricultural intensification for a variety of crops. While the land was still in agriculture, a lot of the habitat value and low water usage offered by ranching was lost.
An agricultural tax incentive — designed to discourage conversion of agricultural lands to residential development — was successful in protecting 37 percent of the remaining rangeland.
But those tax incentives don’t protect those lands from being converted to other agriculture.
Why Should Conservationists Care?
Rangelands protect a lot of valuable wildlife habitat, but their value goes well beyond that. They often connect large blocks of public lands, providing room for migratory species as well as those that have large home ranges.
And new research is finding even more benefits of protecting rangelands, including storing carbon — helping to mitigate the effects of climate change.
Perhaps most significant of all is water savings, especially as Western states like California face severe droughts.
The rangeland that has been converted to intensified agriculture is estimated to use five times more water than all the households of San Francisco combined.
What’s Driving the Change?
Quite simply, economics. It’s not exactly a secret that it’s tough to make a living at ranching. As ranches pass to younger generations, many find that the difficulties are just too much, and choose to sell the property or plant a higher value crop, such as almonds or pistachios.
The authors advocate land-use planning that enables large areas of ranchland to remain intact and for increased incentives to make ranching more economically viable. They call conservation easements “underutilized” for ranchland protection and believe their study can help organizations focus on unprotected properties.
And policies that provide incentives for keeping working ranches working are also vital, they argue. In California, the Williamson Act — passed in 1965 — provided state money allowing local governments to provide tax incentives to protect land for agricultural land uses.
However, state funding of this program ceased in 2009 — and the study’s authors state that this will likely accelerate the rate of land conversion. They urge a return to funding this Act and other policies that provide financial incentives for landowners.
What’s This Paper’s Impact on Conservation?
This paper provides a comprehensive look at regional landscape change, but the tools used to measure that change can be applied beyond Central California.
“Fragmentation of rangelands isn’t just a story of California, it’s a story of the Western United States,” says Cameron. “By analyzing the data to pick up drivers of conversion, we are in a better position to prevent future losses. Knowing where land is protected by different tools can help us prioritize future public and private investments in habitat conservation.”
Cameron calls this approach of tracking loss and protection “conservation accounting.”
Just as the private sector uses profit-and-loss statements to measure the health of a company, this accounting allows conservationists to assess losses against protection.
“It’s an indicator of progress,” says Cameron. “Conservationists have protected key rangelands in California. But this analysis shows that rangeland is still being lost — and points us to the places where our investments can make the most difference.”
Opinions expressed on Cool Green Science and in any corresponding comments are the personal opinions of the original authors and do not necessarily reflect the views of the Nature Conservancy.