Bring in the cows

Grazing may be the best hope for a threatened butterfly

  • A bay checkerspot butterfly on a tidy-tips wildflower on Coyote Ridge near San Jose, California.

    Thomas Nash
  • Conservation biologist Stuart Weiss has found that areas grazed by cattle for a short period, like those on his side of the fence, are better butterfly habitat than ungrazed areas like those across the fence.

    Thomas Nash
  • Cattle eat invasive grasses on one area of Coyote Ridge, before being moved on to another.

  • Native goldfields and poppies blanket Coyote Ridge above California Hwy. 101, where pollution helps invasive grasses thrive, if they're not kept in check by grazing.

    Thomas Nash
 

Page 2

At first, it seems odd to think of nitrogen as pollution. After all, 78 percent of the air we breathe is nitrogen. But that nitrogen is inert. What worries Weiss and others is so-called "reactive" nitrogen.

The compounds that belong to this category -- nitrogen dioxide, ammonia, nitrate, nitric acid -- are biologically and chemically labile. They bounce from the land to the atmosphere to the ocean and back to the atmosphere again, triggering a complex sequence of chemical reactions. "The nitrogen cascade," University of Virginia environmental scientist James Galloway terms it. Among the cascade's byproducts is low-level ozone, which can be toxic to humans as well as trees.

Both plants and animals require moderate amounts of reactive nitrogen in order to synthesize protein. A judicious addition of nitrogen greatly increases crop yields. But an overload can strip soils of calcium and magnesium, leading to lower fertility as well as acidification. Excess nitrogen can also lead to eutrophication -- literally, an enrichment of nutrients -- which disrupts both terrestrial and aquatic ecosystems by spurring the growth of some species at the expense of others.

Nature doles out reactive nitrogen parsimoniously. Lightning, for example, produces enough heat to drive the production of nitric oxide. In addition, many microbes release reactive nitrogen as they decompose organic matter. Microbes that colonize the roots of legumes such as soybeans have the additional knack of taking nitrogen from the air and converting it into a form usable by plants.

Around 1970, human emissions of reactive nitrogen surpassed terrestrial emissions from natural sources, then kept on going. At present, human-related sources release around 190 million metric tons of reactive nitrogen per year, compared to an estimated 90 to 120 million metric tons for natural sources. By 2050, our annual contribution could top 270 million metric tons.

"Of all the chemical cycles essential to life on earth, the one we've changed the most is the nitrogen cycle," says Cornell University biogeochemist Jed Sparks.

Reactive nitrogen makes its way into the biosphere in myriad ways. Some of it flows directly into rivers and streams from agricultural runoff and urban sewage spills. Increasingly, though, it wafts into the atmosphere from exhaust pipes, power plants and factories, as well as from fields doused with ammonia-based fertilizer and manure piles associated with cattle feedlots and dairy farms.

As a result, biologically significant quantities of reactive nitrogen are now reaching the highest places. In the Colorado Rockies, reactive nitrogen has upped the metabolic activity of certain soil microbes and overturned once-stable communities of algae in high-altitude lakes. The plants that compose the alpine tundra are also responding. Some species -- native bunchgrasses, alpine bluebells -- clearly like the extra jolt. Others, however, appear to be losing ground, among them a slow-growing bog sedge.

At lower elevations in the West, introduced grasses stoked by nitrogen are overwhelming many ecosystems, including the coastal scrub of Southern California. Nitrogen is also implicated in the grass invasion occurring in the Mojave Desert, downwind of the smog-filled Los Angeles basin. The grasses expand their range during the winter rainy season, and then, in summer, once the rains end, they dry up. And then, quite often, they burn.

High Country News Classifieds
  • COMMUNICATIONS AND OUTREACH ASSOCIATE
    Communications and Outreach Associate Position Opening: www.westernlaw.org/communications-outreach-associate ************************************************* Location: Western U.S., ideally in one of WELC's existing office locations (Santa Fe or Taos, NM, Helena,...
  • FREELANCE GRAPHIC DESIGNER & PROJECT COORDINATOR (REMOTE)
    High Country News (HCN) is seeking a contract Graphic Designer & Project Coordinator to design promotional, marketing and fund-raising assets and campaigns, and project-manage them...
  • FILM AND DIGITAL MEDIA: ASSISTANT PROFESSOR OF INDIGENOUS MEDIA, CULTURAL SOVEREIGNTY AND DECOLONIZATION (INITIAL REVIEW 12.1.21)
    Film and Digital Media: Assistant Professor of Indigenous Media, Cultural Sovereignty and Decolonization (Initial Review 12.1.21) Position overview Position title: Assistant Professor - tenure-track Salary...
  • REAL ESTATE SPECIALIST
    To learn more about this position and to apply please go to the following URL.
  • ENVIRONMENTAL GEOPHYSICS
    "More Data, Less Digging" Find groundwater and reduce excavation costs!
  • RARE CHIRICAHUA RIPARIAN LAND FOR SALE
    40 acres: 110 miles from Tucson: native trees, grasses: birder's heaven::dark sky/ borders state lease & National forest/5100 ft/13-16 per annum rain
  • CENTRAL PARK CULTURAL RESOURCE SPECIALIST
    Agency: Oregon Parks and Recreation Department Salary Range: $5,203 - $7,996 Position Title: Central Park Cultural Resource Specialist Do you have a background in Archaeology...
  • STAFF ATTORNEY
    Come live and work in one of the most beautiful places in the world! As our Staff Attorney you will play a key role in...
  • ARIZONA GRAZING CLEARINGHOUSE
    Dedicated to preventing the ecological degradation caused by livestock grazing on Arizona's public lands, and exposing the government subsidies that support it.
  • OPERATIONS MANAGER
    Position Summary: Friends of the Inyo (friendsoftheinyo.org) is seeking a new Operations Manager. The Operations Manager position is a full-time permanent position that reports directly...
  • WATER RIGHTS BUREAU CHIEF
    Water Rights Bureau Chief, State of Montana, DNRC, Water Resources Division, Helena, MT Working to support and implement the Department's mission to help ensure that...
  • EXECUTIVE DIRECTOR
    The Amargosa Conservancy (AC), a conservation nonprofit dedicated to standing up for water and biodiversity in the Death Valley region, seeks an executive director to...
  • DEVELOPMENT & OUTREACH ASSOCIATE
    Southeast Alaska Conservation Council is hiring! Who We Are: The Southeast Alaska Conservation Council (SEACC) is a small grassroots nonprofit based out of Juneau, Alaska,...
  • DESERT LANDS ORGANIZER
    Position Summary: Friends of the Inyo seeks a Desert Lands Organizer to assist with existing campaigns that will defend lands in the California desert, with...
  • IDAHO CONSERVATION LEAGUE
    Want to help preserve Idaho's land, water, and air for future generations? Idaho Conservation League currently has 3 open positions. We are looking for a...
  • LUNATEC ODOR-FREE DISHCLOTHS
    are a must try. They stay odor-free, dry fast, are durable and don't require machine washing. Try today.
  • EVENTS AND ANNUAL FUND COORDINATOR
    The Events and Annual Fund Coordinator is responsible for managing and coordinating the Henry's Fork Foundation's fundraising events for growing the membership base, renewing and...
  • EDUCATION DIRECTOR
    Position Description: The Education Director is the primary leader of Colorado Canyons Association's (CCA) education programs for students and adults on the land and rivers...
  • 10 ACRES OF NEW MEXICO HIGH DESERT
    10 Acres of undeveloped high desert land in central NM, about 45 minutes from downtown Albuquerque. Mixed cedar and piñon pine cover. Some dirt roadways...
  • WATERSHED RESTORATION DIRECTOR
    $58k-$70k + benefits to oversee watershed restoration projects that fulfill our strategic goals across urban and rural areas within the bi-national Santa Cruz and San...