Does planting millions of trees make sense?

Feb 15

“The challenge with the shelter belts is they need to be maintained. They are in desperate need of restoration, if they haven’t been removed. Some of them have been removed so they may not be functioning to their best ability. The ones that are fully intact are very large and are going to be very expensive to restore.”

University of Nebraska-Lincoln Professor Sarah Thomas Karle, in a promotional video, is referring to the subject of Conserving the Dust Bowl: The New Deal’s Prairie States Forestry Project (Reading the American Landscape). Published in 2017 by LSU Press, Karle and her co-author Architecture Professor David Karle investigate the shelter belt trees planted across the High Plains in the 1930s. FDR’s plan was to curb “black storms” of dust blowing off drought-ravaged farmland during the Dust Bowl. From 1935 and 1942, the project covered 18,600 miles, on 240,000 acres on 30,000 farms from the Texas panhandle north to the Canadian border. In Nebraska 4,170 miles of shelter belt trees covered 51,621 acres on 6944 farms. Mapping studies in the book show the shelter belts are slowly disappearing. Aerial photography documents existing trees in decline and surrounded by thick undergrowth.

The Prairie States Forestry Project illustrates a deeply held belief in large scale tree planting as an easily implemented, long-term solution to environmental problems. This is called “reforestation” or “sustainable forestry practices” in the language of carbon offsets. Trees absorb carbon dioxide from the atmosphere during photosynthesis and store it as wood (carbon). In theory, this processes balances out carbon emissions produced by human activities. Many large companies like Microsoft, Apple, Google, Amazon and BP align branding with reforestation and the underlying assumption that mass tree planting is a key means of addressing global climate change. A description of Karle and Karle’s book by the MIT Press demonstrates a broader and more confused view of large scale environmental interventions: “Growing, contemporary support for protecting the American rural landscape against commodification for human consumption is rooted in New Deal-era policies that sought to maintain and build upon the natural environmental benefits of existing ecosystems.” This thinking seems to conflate pre-factory farm agriculture with ecology and assumes, the way big corporations claim, that tree planting is a universal environmental benefit.

The High Plains is a semi-arid, elevated section of the Great Plains. It includes most of Nebraska, eastern edges of Wyoming, Colorado and New Mexico and the Oklahoma and Texas panhandles. Before cattle ranchers and farmers arrived in large numbers in the mid-19th century, the land was predominantly short and tall grass prairie. Herd animals like bison, elk, deer and pronghorn lived on the grass. Predator species likecoyotes and wolves were abundant as were many species of birds and small animals. Arapaho, Cheyenne, Comanche, Sioux, Blackfoot, Crow, Kiowa and Pawnee were the prominent nomadic hunter tribes and also formed settlements along major waterways.

The 1830 Indian Removal Act under president Andrew Jackson codified coercion, threats and force to extricate Native Americans from the High Plains and into small reservations. This made way for President Abraham Lincoln’s Homestead Act of 1862. The United States government aimed to expand the western frontier and increase private land ownership by offering 160 acres to citizens or immigrants who would pay fees and make the land “productive” by farming or cattle ranching. The effort began during a period of consistent rainfall. The land seemed lush. Many people took the offer. The settlers drastically reduced the numbers of wild animals by killing them directly or removing habitat. They built fences, redirected water and introduced invasive plant species. In the decades following 1862, farmers and ranchers saw early success succumb to the natural high prairie conditions: shallow soil, little rainfall, high, persistent wind and extreme temperatures. The world grain market fluctuated during and after WWI. In an effort to speed up crop returns, farmers abandoned soil conserving practices in favor of deep tilling. A longer cycle of drought in the 1930’s ushered in the Dust Bowl.

President Roosevelt’s Prairie States Forestry project spent $74 million over 12 years from 1935 to 1947 on shelter belt tree planting in the High Plains. The University of Nebraska Drought Mitigation center points to a return to normal rainfall by 1941 and the introduction of new irrigation methods as reasons drought conditions ended for farmers. Other studies demonstrate the shelter breaks did reduce soil erosion in pasture land. An assessment of their relative success or failure is irrelevant now. The ecological value of wooded areas on land suited to short grass prairie is a timely question, the small farms and the communities they sustained are rapidly dwindling, and there is now a different, all encompassing problem for the High Plains.

Native tall and short grass prairie is the most endangered ecosystem in North America. To do away with prairie is to give up on the entire webs of species dependent on the plants. According to a study in Biological Conservation, in April 2019, 40% of the world’s insects are endangered. Habitat loss, agro-chemical pollutants, invasive species and climate change are the main drivers of the decline in insect populations and overall biodiversity. Citing the report, the United Nations Environmental Program newsletter said that strong language in the researchers conclusion reflects the severity of the problem. “The [insect] trends confirm that the sixth major extinction event is profoundly impacting life forms on our planet... Unless we change our ways of producing food, insects as a whole will go down the path of extinction in a few decades... The repercussions this will have for the planet’s ecosystems are catastrophic to say the least.”

The Prairie States Forestry Project included many invasive species such as Eleagnus angustifolia (Russian Olive), Caragana arboresens (Siberian Peashrub), Elmus parvifolia (Chinese Elm), Lonicera siberia (Siberian Honeysuckle.) Invasive species do not sustain balanced ecosystems because insect lifecycles depend on specific native species. The Siberian Honeysuckle, for example, alters habitat by decreasing light availability, depleting soil moisture and nutrients, and by releasing allelopathic chemicals which suppress the growth of other plants.

In addition to sustaining wildlife, prairie grasses perform the exact function expected from the shelter belt trees. Prairie grasses are the best soil anchors on earth with roots penetrating from 3-15’ deep forming a dense network of filaments. The tiny spaces created by the roots form soil aggregates. The spaces between the aggregates allow water to penetrate deep into the ground. This replenishes ground water and stores reserves in the plants for use during drought or high wind. One acre of prairie can absorb 9” of rainwater per hour before runoff occurs. In addition, prairie ecosystems are excellent windbreaks. The grasses are highly effective carbon sinks because most of the plant mass is underground. And, prairies are renewed by wildfire.

The major impediment to sustaining wildlife is the amount of space currently being used by large farms. Contrary to the romanticized view of farms expressed by the MIT Press reviewer, the report in Biological Conservation states: “A rethinking of current agricultural practices, in particular a serious reduction in pesticide usage and its substitution with more sustainable, ecologically based practices, is urgently needed to slow or reverse current trends, allow the recovery of declining insect populations and safeguard the vital ecosystem services they provide.”

U.S. farmland is increasingly owned by single, large investors. Bill Gates, for example, owns 242,000 acres of farmland in the United States including 20,588 in Nebraska. According to the University of Nebraska, the total number of farms and ranches in Nebraska declined by 500 from 2021 to 2022. Jeff Bezos owns 420,000 acres of US farmland. Ted Turner wins at 2 million acres. In a 2014 letter to investors, Warren Buffet said, as an investment, farmland has “no downside and potentially substantial upside” because farmland is not subject to stock market volatility. Investors believe, based on recent trends, both land and agricultural product will increase in value. This point of view suggests either ignorance or denial not just about the potential mass extinction of pollinators but the condition of the Ogallala Aquifer.

The Ogallala or the High Plains aquifer is one of the world's largest. It covers approximately 174,000 square miles in portions of eight states (South Dakota, Nebraska, Wyoming, Colorado, Kansas, Oklahoma, New Mexico and Texas). The Ogallala supports $35 billion in crop production each year along with water for cities and rural towns. Large scale extraction started after WWII with center pivot irrigation and the adoption of gas motors to pump wells. Now the Ogallala Aquifer is drying up.

Research from the U.S. Geological Survey and studies by Stanford University, West Texas A&M and others predict that as much as 70% of the Ogallala will be unable to support irrigated crop production within the 50 to 80 years. Over 90% of Ogallala’s supply is used for irrigation and livestock. It also contributes to municipal water systems and other industries. Drought and heat caused by climate change could significantly increase the rate of decline. The Department of Homeland Security estimates some parts of the aquifer have less than 25 years left of available groundwater. Once depleted, the aquifer will take over 6,000 years to replenish.

“It was once a barren land. The angular hills were covered with scrub cedar and a few live oaks. Little would grow in the harsh caliche soil. And each spring the Perdenales river would flood the valley. But men came and worked and endured and built” said Lyndon Baines Johnson about the Texas his grandfather, Sam Ealy Johnson Sr., moved to in 1846. Earlier settlers, at the beginning of the 19th century, had already altered the Texas Hill country by assuming that grass-covered hills meant deep soil capable of sustaining herds of cattle. By mid-century the hills were bare. Many decades later, Lady Bird Johnson would operate under a different set of assumptions about land. Instead of a set of obstacles to be altered and surmounted, wilderness should be preserved or restored. The Lady Bird Johnson Wildflower Center at the University of Texas at Austin aims to protect and learn from the few remnants of wild prairie and demonstrate the urgent need to include rewilding in “America’s breadbasket.”

In the future, prairie ecosystems will be the focus of award winning graduates from Harvard’s Graduate School of Design like Sarah Karle. The Bill Gates’s, Jeff Bezos’s and Ted Turners will be true leaders by funding this work. They will donate most of their acres to rewilding and promote the creation of smaller, more diversified farms. This will not only sustain pollinators and create true shelter from extreme weather. It also has the potential to recreate the smaller, more localized economies Karle and Karle would aim to protect by restoring the shelter belt. The new shelter belt is prairie.

Does planting millions of trees make sense?

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