Ag is the Biggest Threat to Biodiversity and Ecosystems

Farmland Rocky Mountain Front, Montana is a biological desert of exotic plants (wheat) that covers tens of thousands of acres. Photo by George Wuerthner

Most land trusts and many conservation groups frequently ignore the impacts of Agriculture and focus on urbanization and sprawl as the main threat to biodiversity and ecosystems.

Gallatin Valley fragmented by Ag fields, Montana. Photo by George Wuerthner

A good example is the Teton Land Trust, Idaho. A recent story about their board president, John Nedrow, a farmer, talks about how he put a conservation easement on his farm to “protect” it from habitat destruction.

To quote from the article, “I like that we continue to own our property, even though it’s protected by a conservation easement,” said Sheila Nedrow, John’s wife. “It’s an easement, so we need to protect those conservation values. We can’t destroy the habitat, but we’d never want to do that anyway. But still, it’s our land to manage and continue to produce for our farm.”

Nedrow grows barley and hay, both exotic monocultures of exotic plants. And he dewaters the near-by river to water his crops, yet another unaccounted assault on native biodiversity.  And I presume, but do not know, that he uses fertilizers and pesticides that further pollute the water and soil. His entire farming operation is destroying habitat.

It is not surprising that farmers do not see row crops, hayfields, as habitat destruction. However, one expects a more ecologically informed staff at land trusts. Unfortunately, the Teton Land Trust is not unique. Many land trusts overlook or maybe are merely ignorant of the real impacts of agriculture.

Hayfield near Ashton Idaho, an example of a mono crop that is removed annually. Photo by George Wuerthner 

While I have no problem with conservation easements to preclude residential development for a host of other reasons, however, suggesting that on-going farming and ranching “preserve” biodiversity and wildlife habitat ignores the fact that Ag is the most significant threat to wildlife habitat and biodiversity across the Nation.

Conservation easements may protect “open space,” but open space is not the same as suitable wildlife habitat.

Agriculture is far and away more destructive of wildlife habitat and biodiversity if for no other reason than it impacts more than a hundred times more land than urbanization and sprawl.

Misunderstanding abounds about land use in the United States, and their environmental consequences abound. Habitat destruction is the largest factor in species endangerment.

Most of this habitat destruction is due to Agriculture, and a lesser degree, logging. Row cropping, in particular, fragments and replaces natural habitats.

Conversion of the wheat or cornfield to a housing tract may well increase biodiversity. With its abundance of shrubs, trees, and other habitat niches, my suburban neighborhood, even when you consider the habitat loss created by the houses themselves, still supports far more species of wildlife, including native insects, amphibians, birds, and mammals per acre than most row crops or even hay fields.

Here is a view between Ashton and Tetonia Idaho. The ag field on the left is a biological desert. The house is across the street and surrounded by native trees and shrubs. Which has more native biodiversity? Photos by George Wuerthner 

For instance, a field of wheat or corn is a biological desert except for the most intensively urbanized lands like Manhattan Island, most urban landscaping with trees, shrubs, and other habitats that provides more biodiversity than your typical agricultural row crop.

One should not assume that I promote more urbanization. Sprawl brings other impacts like more traffic on roads, which can kill wildlife and fragment habitat, promote the spread of weeds, while the pavement is impervious to water infiltration, and many other impacts. Many others have articulated the impacts of subdivisions.

Instead, I suggest that we try to minimize as much as possible both sprawl and agriculture.

Part of the reason for this myopic view of Ag impacts is Americans generally love bucolic landscapes. A barn with a green field with a few cows grazing a grassy hillside evokes rural harmony to many folks.

Dairy cows, farm, autumn, Huntington, Vermont photo by George Wuerthner

Yet by far, the greatest impact on the American landscape comes not from urbanization but rather from agriculture. According to the U.S. Department of Agriculture, farming and ranching are responsible for 68 percent of all species endangerment in the United States (Flather 1992).

Agriculture is the largest consumer of water, particularly in the West. For instance, in Montana, 96% of the water consumed is for agriculture (Irrigation in Montana: Eco Northwest 2008) Most water developments (reservoirs and dams) would not exist if not for the demand created by irrigated agriculture. In most cases, taxpayers foot the majority of these impoundments’ cost—another subsidy to agriculture.

Owyhee Reservoir Oregon. Photo by George Wuerthner

If the ultimate causes and not proximate causes for species extinction are considered, agricultural impacts would even be higher. Yet scant attention is paid by academicians, environmentalists, recreationists, and the general public to agriculture’s role in habitat fragmentation, species endangerment, and declining water quality.

The ironic aspect of this head-in-the-sand approach to land use is that most agriculture is entirely unnecessary to feed the Nation. The great bulk of agricultural production goes toward forage production used primarily by livestock.

Beef is a particular climate offender, requiring 28 times more land, six times more fertilizer, and 11 times more water to produce than other animal proteins like chicken or pork.

For instance, in the United States we have 95 million acres in corn—that is the size of Montana. Some 48% of that corn production is fed to livestock, not for direct human consumption. By comparison, we have only 50 million acres of wheat; almost all consumed directly by humans.  Another 75 million acres are planted to soybeans, and again the vast majority is fed to livestock.

Cornfields at farm in Richmond, Vermont, Photo by George Wuerthner

A small shift in our diet away from meat could have a tremendous impact on the ground regarding freeing up lands for restoration and wildlife habitat. It would also reduce the poisoning of our streams and groundwater with pesticides and other modern agricultural practices residues.

Dairy cows along Snake River Plain, Idaho. Photo by George Wuerthner 

Most of the information in the following summary is available from the USDA Economic Research Service publication “Major Uses of Land in the United States.”

Overview of Land Use in the United States-The U.S. has 2.3 billion acres of land. However, 375 million acres are in Alaska and not suitable for agricultural production. The land area of the lower 48 states is approximately 1.9 billion acres.

To put things in perspective, keep in mind that California is 103 million acres, Montana 94 million acres, Oregon 60 million acres, and Maine 20 million acres.

Developed Land-urbanization, covers only 69 million acres. That is acreage a bit more than the size of Oregon spread across all 50 states.

This development amounts to a little more than 3 percent of the land area in the U.S.,more%20than%20double%20by%202060.&text=The%20average%20population%20density%20of,90%20people%20per%20square%20mile.

Yet this small land base is home to 75 percent of the population. In general, urban lands are nearly useless for biodiversity preservation. Furthermore, urbanized lands, once converted, usually do not shift to another use. Nevertheless, as a percentage of the country, it is not the major factor destroying biodiversity or natural ecosystems.

In the West with its lower human population, the percentage of developed land (meaning all cities, highways, factories, and subdivisions) is tiny. For instance, in Montana, a GAP analysis (which uses computer analysis of air photos and can detect individual houses) found that only 0.17% of the state was developed. Just irrigated crops, of which half is hay, occupies more than 5% of Montana.

This difference between urbanized and developed land compared to the acreage in AG land is significant. American farmers planted more than 95 million acres of corn, with the majority going to feed livestock.  Another 75 million acres were planted to soybeans last year alone. These two crops affect more of the U.S. land area than urbanization, rural residential, highways, railroads, commercial centers, malls, industrial parks, and golf courses combined.

Cropland- About 392 million acres in the U.S. are planted for crops-up by almost 50 million acres from three decades ago.,forestland%20has%20decreased%20more%20rapidly.

Thus cropland acreage is the equivalent of about four states the size of Montana. Four crops — feeder corn (95 million acres), soybeans (75 million acres), alfalfa hay (61 million acres), and wheat (50 million acres) — make up 80 percent of total crop acreage. All but wheat are primarily used to feed livestock.

It’s critical to note that much of this cropland production relies on dozens of Ag subsidies from low land taxes to price supports.

Environmental subsidies are also significant. Loss of biodiversity, water pollution, wind erosion, and soil losses, pesticide poisoning, and the removal of native vegetation are among the many ecological costs that are externalized. Indeed, if a significant number of farms were abandoned and “rewilded,” the net benefits would far outweigh any food production.

Indeed, the loss of these farms would hardly affect food production since we devote most of our farm acreage to feeding cows, not people.

The amount of land used to produce all vegetables in the U.S. is less than 3 million acres.

Vegetables in market. Photo by George Wuerthner

Range and Pasture Land- Some 655 million acres, or about 34 percent of the U. S. excluding Alaska, are grazed by livestock. Consequently, lands grazed by livestock is an area the size of 7 states the size of Montana. Grazed lands include rangeland, pasture, and cropland pasture. More than 309 million acres of these grazed acres are federal, state, and other public lands. Another 130 million acres are forested lands that are grazed.

Cattle grazing the California desert. Photo by George Wuerthner

Forest Land- Forest lands comprise 631 million acres. Some 501 million acres are primarily forest (minus lands used for grazed forest and other special categories).


The red line just below the blue at the top is the amount of developed land (meaning urbanization)

The USDA report concludes that urbanization and rural residences (subdivisions) “do not threaten the U.S. cropland base or the level of agricultural production.” This conclusion does not mean sprawl doesn’t have impacts where it occurs. But the notion that sprawl is the greatest threat to biodiversity is false. Indeed, the amount of land in crops has increased, primarily by converting rangelands or forestlands into cropland.

Conclusions that place sprawl ahead of agriculture regarding biodiversity impacts are due to faulty accounting methods and a general bias that favors agriculture as a “good” use of the land.

Furthermore, there are other viable means of controlling sprawl. They include land-use planning, zoning, fee purchase, and conservation easements.


Oregon has statewide zoning and abrupt borders between urban land and ag land. Photo by George Wuerthner 

To suggest that promoting Ag will preclude sprawl is non-sensical given that nearly all new subdivisions occur on former farms or ranchlands.

Converting urban lawns into gardens can produce much of the vegetables and fruits consumed by Americans. Eugene Oregon Photo by George Wuerthner-

If promoting Ag is your best land conservation strategy, you might rethink your assumptions. It does not work anyplace there is a high demand for land.

Plus, once land prices rise above what someone can garner by growing crops or cows, the land will be subdivided.

Despite acreage being paved over, malled over, or overbuilt with condos, developed land is generally concentrated in and near cities. The loss of nearby farm or ranch land is insignificant compared to the total acreage available in the U.S.

The real message here is that we can afford to restore hundreds of millions of acres in the U.S. if we shift our diets away from meat, cut Ag subsidies, and did a full accounting of the real costs of Agriculture.

Many organizations spend their time-fighting sprawl and championing agriculture as a benign use of the land. If a similar effort were directed toward reducing agricultural production, we would produce far greater protection and restoration for declining species, endangered ecosystems, and ecological processes.

When critics suggest that we don’t have the money to buy land for wildlands restoration, they forget agricultural subsidies, which amount to billions of dollars. Indeed, this past year, the Trump administration gave Ag producers more than $28 billion in subsidies.

For what we spend to prop up marginal agricultural producers, we could easily buy a significant amount of the private farm and ranch land in the country and add it to our public lands’ heritage. Land acquisition would be a far more effective way to contain sprawl, restore wildlands, bring back endangered species, clean up water, slow the spread of exotic species, and reduce soil erosion.



  1. Karl Avatar


    Your best piece ever!

  2. Lyn McCormick Avatar
    Lyn McCormick

    What, you mean do basic cost-benefit analysis ? And, what about large scale renewable energy projects ?

  3. Maggie Frazier Avatar
    Maggie Frazier

    The idea that these subsidies are going to LARGE farm operations, rather than the small family farms that we are losing more of every day really galls me. Its just more factory farming, really. The damage that big ag has been & is doing, on top of the livestock grazing programs, needs to be put closer to the top of the list of things that must be addressed SOON! The US sure has moved closer to being one of the “lesser developed” countries – when it comes to saving the planet. Are we really going to allow the current mindset to continue to put us deeper into climate change?

  4. Beeline Avatar

    A comment on the cycle of development or and destruction, depending on how you look at it.

    Being raised on a family farm, I experienced agriculture at a level that left hedge rows along the roads and native shrubs in non-tilled places. Our water well was only about 60 feet in depth. The human density was low and there was a real community feeling. It is interesting to note that there was quite a mix of different races as well. We all got along pretty well growing our preferred diversity of crops.

    We had rabbits, quail, doves and a lot of passerine species of birds plus insects which are presently quite rare. There were also a lot of raptors including owls, hawks and kites. Hunting was also very much a part of the culture in those days.

    In the late 1950’s city and county officials decided that our agricultural town should grow. Real estate developers lobbied harder for opening areas to urban development which was fueled in part by oil field revenues from the petroleum areas to the west. Taxes were raised which caused economic stress on farmers and regardless of how good the soils were, agricultural land fell to the bulldozers. Canals and old marshy areas were filled in.

    I watched my grandfathers field which grew so many crops get flattened out and sub divided. A couple miles away 40 acres owned by a jolly old Italian fellow got flattened for a mall. The old slough where I had so many adventures as a boy got filled in for a strip mall. The new residents littered the remnants of what little habitat remained and the once plentiful wildlife was gone as well. The city had to drill water wells down to 600 feet to supply the monster that they had created.

    The increased population just brought more problems. So the city increased taxes even more and more farms went bust as the suburbs continued to spread. Wild lands that were previously good wildlife habitat were tilled until little was left as the cycle of destruction continued spreading out farther and farther.

    This kind of thing has happened all over the U.S. and still the various local governments only seem to respond to the magic words of ‘growth’ and ‘development’.

    So no, it does not seem to me that the population is willing to give up its bread and circus’ world, and simply refuses to take on the necessary measures to implement real conservation.

    1. Maggie Frazier Avatar
      Maggie Frazier

      I grew up in a small town with what today would be small family farms all around. My grandparents who no longer farmed their land were next door to a farm – in the village! My dad for years had a pretty good sized garden every year in the half acre or so in back of our house – in the village. It was a great place to grow up – the nearest city was about 30 minutes away – then a highway came thru & a lot changed – as it does. Growth & development aint all its cracked up to be – in any way shape or form. I still live near there but in what is my opinion – the country.
      Youre right – people dont want to give up convenience & want more & more new & “better”.
      Sorry I sort of meandered away from the issue.


George Wuerthner is an ecologist and writer who has published 38 books on various topics related to environmental and natural history. He has visited over 400 designated wilderness areas and over 200 national park units.

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George Wuerthner