Tag Archives: biodiversity

The most powerful family on earth

Prairie grass in the Konza Prairie Preserve in the Flint Hills of Kansas by Betsey CrawfordUntil man duplicates a blade of grass, nature can laugh at his so-called scientific knowledge. 
~Thomas Edison~ 

Such a tiny word — poa, Greek for grass — to encompass one of the great life forces on earth. The Poaceae are the fifth most species-rich plant family with over 11,000 plants. They populate a quarter of the planet’s land and half the United States. Along with forests, they are among the most important stabilizers of both soil and climate. One of the most adaptive plant families, they live on every continent. They’re the top source of nutrition worldwide.  They’re the basis of human civilization. Every one of us is alive thanks to grass. 

We may even have evolved into humans because of grass. There are grass pollen fossils dating from 70 million years ago, but it wasn’t until 5 to 8 million years ago that the vast grasslands we inherit formed. It was a period of cooler, drier climate and water-thirsty forests began to diminish, opening space for the adaptable grasses. The open landscape helped foster bipedalism among primates, which ultimately helped stimulate the development of our large brains.

Anatomy of grass artwork by Kristin Jakob for the California Native Plant Society

Artwork by Kristin Jakob for the California Native Plant Society. Thanks to both for permission to use this lovely piece.

Our hunter-gatherer forebears would have eaten the seeds of grasses along with other seeds, fruits, and tubers. Twelve thousand years ago, they began to plant them. Though we can’t know what seeds the first farmers started with, we do know that all the early civilizations grew with grass. Wheat, barley, and rye in the Mideast. Rice, millet, sorghum  in China. Corn in Mesoamerica. Rice and sugarcane in India and Southeast Asia. Sorghum, millet, and tef in Africa. Over the millennia grasses have fed humans and the animals we depend on. They have built, roofed, fenced, heated, and furnished our houses. Cleaned our air and waters. Formed our soil. Made baskets, boats, and paper. They have cured diseases and powered our cars. 

All this inspires the anthropocentric idea that humans have harnessed grasses to meet their needs and desires. But I like the counter take of some botanists: it’s grass that has bent the human. What better way to ensure your survival than to hook this clever species with the handy thumb and ability to plan for the future? Provide enough nutrients to maneuver them into planting you everywhere they can, every single year for 12 thousand years. Induce their browsing animals to open up more land for you to grow, all the while fertilizing your roots. Convince them to plant 40 million acres of you around their houses. And then spend hours every week lovingly feeding and watering you while fending off pests. That’s power! I toyed with calling this essay ‘Our overlords.’

Worldwide distribution of grasslands. Image courtesy of Missouri Botanical Garden.

Worldwide distribution of grasslands. Image courtesy of Missouri Botanical Garden.

But that has negative connotations, and grass is a miracle. You don’t cover a quarter of a very varied planet without being a highly adaptable genius. In the US we are most familiar with the prairie ecosystem that extends through the midwest from the Gulf of Mexico north into Saskatchewan and Manitoba. South America has similar systems in the pampas and llanos. Trees and grass combine to form the savannas of Africa, India, Southeast Asia, and the Cerrado in South America. The vast expanse of the Eurasian steppes extends from Eastern Europe well into China. 

In the eons before they formed these priceless expanses, grasses evolved several traits that would secure their eventual success. They are wind-pollinated, tossing their pollen to the air. The wind spreads it far and wide, creating a lot of opportunity for pollination over a large area. They form deep roots, up to five times the height of the plant. This vast ecosystem supplies their needs for water, nutrients, and stabilization. And not just for themselves, but for the soil they, and the rest of us, depend on. 

The roots of prairie plants, grasses as well as flowers. Artwork from the Conservation Research Institute.

The roots of prairie plants, grasses as well as flowers. Note the meager extent of lawn grass roots on the far left. Artwork from the Conservation Research Institute

Crucially, they developed a key variant in the photosynthetic pathway. C4 photosynthesis allows for more efficient use of sunlight and water in the creation of carbohydrates. This process allows grasses to use less water, grow in nutrient-poor soils, and allocate more of their biomass to roots. C4 plants are very efficient at pulling in carbon dioxide and sequestering it in their miles of roots. This gives grassland preservation a pivotal role in climate stabilization.

They are also imperative for preserving biodiversity. Grasslands are not only grass. They form a matrix for many other plants that grow with them. The Missouri Prairie Foundation reported that in one of its restored prairies a record of 46 separate native plant species was found in a 20 by 20 inch plot. They provide food and habitat for countless birds, bees, butterflies, mammals, reptiles, microbes, fungi, and other beings that are part of the web of life on earth. They have co-evolved with some of the most majestic life forms on the planet: buffalo, gazelle, zebra, giraffe, elephant. 

Pronghorn antelope in the Pawnee National Grasslands, Fort Collins Colorado by Betsey Crawford

Pronghorn antelope in the Pawnee National Grasslands, Fort Collins Colorado

Grasses both depend on these and domestic grazers to keep land open for them and also have ways to protect themselves from overgrazing. Various toxic phenols and alkaloids, including cyanide, increase as grazing pressure rises. Phytoliths, minute shards of silica, wear grazer teeth down. On the other hand, grasses need grazers, and so keep their budding crowns just under the soil so that they aren’t damaged by nibbling muzzles. As the grazers clean off the upper stalks, new shoots have ample air and light to grow. In the meantime, grazers deposit fertilizer and move on, allowing grasses time to recover.

Some of the most diverse places on the planet are in grasslands. But our tendency has been to treat them as wasted space waiting for us to make them productive. Thus 99% of the American prairie has been plowed, planted, developed. The South American Cerrado is headed in the same direction. Using large, open areas for agriculture certainly makes sense. But the current state of monoculture farming — growing single species annuals with shallow roots, using yearly tilling and high nitrogen fertilizers along with artificial pesticides and herbicides — means that standard agriculture ruins the most important gifts of grasslands. Soil erosion is high, biodiversity and carbon sequestration are low to nonexistent.

This vine mesquite (Hopi obtusa) on a Missouri roadside dangles its vivid anthers, ready to send their pollen to the wind. The feathery stigma at the other end of the filament are ready to receive pollen. Photo by Betsey Crawford.

This vine mesquite (Hopi obtusa) on a Missouri roadside dangles its vivid anthers, ready to send their pollen to the wind. The feathery stigma at the other end of the white filaments are ready to receive pollen.

I love the subtle beauty of grasses with their feathery flowers and am deeply moved by grasslands. I’m not sure where this came from, since I grew up in suburban New York. But one of the most moving experiences of my life was standing in a grassland in South Dakota. I was driving back roads north along the Missouri River, and a stretch took me into the short grass prairie of that dry area. I was up to my knees in sun-filled grasses, flowing like golden water with the wind. It was so hot the air itself was an intense presence. Despite the wind, there was utter quiet. Everything else fell away to nothingness. At that moment, swept into the warm, moving air, I was grass.

As we all are. We share up to half of our genes with grass, a legacy from common ancestors. Sixty percent of human caloric consumption worldwide is grass-based. We are literally grass. We are formed by them and we are inextricably bound into a miraculous matrix of interdependence. To see this clearly is to plant ourselves into the very roots of life. It means we live on earth not as user but as participant, surrounded by equally important partners. We can then hear their message. The skill grass chose us for — our ability to plan for the future — is being called forth to help all of us prosper on our mutual planet.

Pawnee National Grasslands in Fort Collins, Colorado by Betsey Crawford

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What we can do: gardening to save half the earth

Creative habitat with native plant gardening

I once designed a landscape for clients who wanted their property to blend in with the oak and hickory forest surrounding them. They’d read an article in the local paper about my advocacy for native plant gardening and liked the idea. This was at the eastern end of Long Island, in New York, which is blessed with glorious native shrubs. We had a great time working with beautiful viburnums, vivid oakleaf hydrangeas, spicy bayberry, sweet-smelling clethra, native azaleas, and a lovely native rose.
 
A couple of years later, after listening to me give a talk on native plants, a woman who lived in the same neighborhood came up. She told me that her neighbors felt sorry for my clients, who had “spent all that money and ended up with something so wild looking.” A landscaper told me the same thing. He would drive prospective clients around to see what they preferred. He liked what I had done and kept hoping to find someone who agreed. They never did. Too wild, they would say, about the landscape pictured above.
 
So a new housing development carved out of a forest that began at the end of the Wisconsin glaciation 11,000 years ago ended up with house after house with the same design: lawn to the street with a kidney-shaped area of varying size containing one or two non-native trees. These were underplanted with a frill of non-native — and sometimes invasive — shrubs. Some would then box themselves in with a wall of unspeakably dull privet hedge. Though not invasive in the acidic soil of eastern Long Island, privet is taking over forests in many other states across the country.
 
Masai Mara National Reserve, Kenya. Photo by David Clode via Unsplash

Masai Mara National Reserve, Kenya. Photo by David Clode via Unsplash

I am not easily discouraged and, by and large, found the experience fascinating. I began to appreciate the theory that our landscape choices reflect our evolution on the savannas of East Africa. Deep in our consciousness, do we associate open grassland punctuated by small areas of trees and shrubs with safety? We can see our predators. So we are forever mowing down and hacking back the wilderness that we find threatening.
 
More immediate history has played a powerful role. After (and since) World War II there was a huge push to build houses and suburbanize farm fields and woods throughout the country. To soften the stark, boxy neighborhoods developers chose trees and shrubs for speedy growth, regardless of where they came from. Many of us grew up with a landscaping language that saw native plants as weeds. Native plant gardening was a laughable concept.
 
The archetypal post World War 2 suburb: Levittown, New York. Photo by Mark Mathosian via Flickr

The archetypal post-World War 2 suburban development: Levittown, New York. Photo by Mark Mathosian via Flickr

 
No more native hedgerows, filled with flowers and berries, birds and bees. Now hedges were all the same, uninteresting plants, shaved into a box. Rhododendrons, pulled out of the woods and marched along the fronts of houses, were then pruned so hard they never bloomed. Flat slabs of lawn became sacrosanct, lined with fast-growing birches and aggressive maples. When we wanted something unusual, or more colorful, we imported delicate red maples from the forests of Japan. Or dragged blue spruces out of the mountains of Colorado. When they didn’t prosper in the heat of our summers, we sprayed them with poisonous compounds. We got those from chemical companies that had flourished during the war and now needed new markets.
 
It didn’t take long for a landscape that grew out of a hodgepodge of interests to become the norm. So much so that a woman who tried growing vegetables in her front yard in Detroit was taken to court last year. There is no reason on earth to essentially pave our yards with mown grasses that can’t survive without excess water and chemicals. And yet we have so accustomed ourselves to it that it’s the law in certain places. It is, as the Zen masters say, a story we tell ourselves. And we can tell ourselves a different one.
 
Creating habitat with native plant gardening: a cloudless sulphur (Phoebis sennae) on helmet flower (Scutellaria integrifolia) in Osceola, Missouri, by Betsey Crawford

Cloudless sulphur (Phoebis sennae) on helmet flower (Scutellaria integrifolia) in Osceola, Missouri

And must. If we are going to save half the earth to protect the biodiversity that every creature on the planet depends on, we need to change our landscaping story. We need another language. Satellite images tell us that lawns cover over 40 million acres in the lower 48 states. Half of homeowners also garden, which means we have upwards of 65 million gardeners. Allow them each an average eighth of an acre and homeowners in the US alone control up to 50 million acres of land.
 
Activists and organizations, with good reason, tend to focus on projects like saving the vast Amazon basin. But it’s also vitally important that we preserve, create, and connect local habitat everywhere we can. Mercifully, as gardeners, we don’t need to deal with the competing interests of eight separate countries. Or 400 indigenous nations. Or corporations itching for access to petroleum, minerals, beef, or palm oil. We can grab a shovel, put some plants in the ground, and make an immediate difference.
 
But it depends on the plants we choose, and the reasons we choose them. If we are growing for biodiversity, we have a rich and rewarding path ahead. Butterflies, birds, bees, moths, and other beings will discover our gardens. But it’s not what we’re used to. It may not be tidy. It goes through seasonal transitions. It’s more unpredictable. You leave your leaf litter on the ground to foster nutrition and manage moisture. There are bugs, and they are so crucial we need to aim for more of them, happily living in the leaf litter. In other words, it’s wild, or should be. We can organize and tame it, shape the landscape, choose and place plants to create beauty. But our fellow creatures need us to embrace wildness, no matter how urban our environment.
 
Creating habitat with native plant gardening: a black swallowtail (Papilio polyxenes) on the aptly named butterfly weed (Asclepias tuberose) in Osceola, Missouri. Photo by Betsey Crawford

Black swallowtail (Papilio polyxenes) on the aptly named butterfly weed (Asclepias tuberose) in Osceola, Missouri

Birds and bugs have evolved over eons to adapt to the native plants they eat and nest in. And that’s what they need to survive. The monarch butterfly larva eats milkweed. That’s it. If there are no milkweeds, there will be no monarch butterflies or any of the other 11 species that specialize in milkweeds. Beautiful and fascinating plants, milkweeds’ lovely flowers turn into extraordinary seed pods. Once opened, thousands of silky threads float their attached seeds through the air. But milkweeds are not conventionally pretty. They’re a little wild looking. Those silky seed threads could land in the lawn! You would be hard pressed to find milkweeds in a nursery selling plants to the general public.

Creating habitat with native plant gardening:: common-milkweed-seedhead-asclepias-syriaca-Genesis-farm-Blairstown-New-Jersey-by-Betsey-Crawford

Common milkweed (Asclepias syriacus) seed pod and seeds

If there are enough open meadows and wetlands, there will be enough milkweeds. But as we destroy more and more of those, it’s left to gardeners to keep milkweed available for monarch butterflies. After we build and pave our neighborhoods, it’s up to us to use native trees as street trees to support the hundreds of life forms they shelter. Instead, we use pear trees imported from Asia. They grow upright for many years, so don’t need a lot of pruning. They provide a profusion of white flowers when everyone is desperate for a sign of spring. They aren’t susceptible to being eaten by our insects, so harbor no life at all. From a highway department’s point of view, they’re perfect. From a biodiversity standpoint, they’re a disaster.
 
Plants produce toxins to protect themselves from too much predation. Over millions of years, local bugs have evolved enzymes to neutralize those toxins. When you introduce a plant that insects didn’t evolve with, they can’t eat those toxic leaves. This may seem like a win for gardeners and planners. But not feeding your insects means you’re not feeding birds, lizards, frogs, small mammals, fish. You’re not allowing butterfly larvae to mature. Insects that we depend on to break down plant and animal detritus — thereby returning nutrients to the soil all life depends on — die out. First flowers and then whole plants disappear because there are no pollinators. Naturalist E.O. Wilson calls insects “the little things that run the natural world.”
 
Creating habitat with native plant gardening: a gorgon copper butterfly (Lycaena gorgon) on California buckwheat (Eriogonum fasciculatum) Ring Mountain, Tiburon, California by Betsey Crawford

Gorgon copper butterfly (Lycaena gorgon) on California buckwheat (Eriogonum fasciculatum) Ring Mountain, Tiburon, California

The idea of gardening for insects may seem alien in a world full of products to exterminate them. But nature has been at this way longer than we have. If insects consistently defoliated plants, there would be no photosynthesis, no plants, no animals, no us. The caterpillars munching your oak leaves are themselves likely to be eaten by birds or parasitized by wasps. If they make it past such hurdles, not much will get eaten before it’s time to spin their cocoons. Introduced aliens, like gypsy moths and Japanese beetles, can do a lot of damage because they have no natural predators. That’s the problem with all non-native species, animal and plant.
 
Over 5000 non-native plant species have taken over vast swathes of our natural world. It’s such a mess that in many places the only way to preserve the natural ecosystem is to first reclaim it. Eastern deciduous forests are being smothered by bittersweet and mile-a-minute vines. Autumn olive is choking Utah’s great river canyons. Wetlands are disappearing under the seductively pretty haze of lythrum’s magenta flowers. Some plants, like the melaleuca that is destroying Florida’s Everglades, were brought here to do what they did. Developers wanted to drain the swamp to contain mosquitos and allow building. A few invaders arrived by accident. Others, like the oats and annual grasses that have taken over the hills of California, were grown for fodder. The eucalyptus and pampas grass spreading along the west coast were among many, many plants brought here as novel ornamentals.

 

Creating habitat with native plant gardening: a pipevine swallowtails (Battus philenor) feed exclusively on plants in the Aristolochia family, the pipevine plants. Not only have they evolved to deal with the toxins of this family, but by ingesting them they make themselves toxic to prey. Photo by Betsey Crawford

Pipevine swallowtails (Battus philenor) feed exclusively on plants in the Aristolochia family, the pipevine plants. Not only have they evolved to deal with the toxins of this family, but by ingesting them they make themselves toxic to prey.

The same sad trajectory is true for plant diseases and insects. In British Columbia, I drove past mile upon mile of boreal forest destroyed to the horizon by an Asian beetle. We are losing our native ash trees to the accidental importation of emerald ash borer. An early casualty of imported plants was the complete destruction of the eastern chestnut in the nineteenth century. When the European chestnut came here it carried a fungus to which it was resistant. The native one was not.
 
It’s a very complex problem, made even more so by unpredictability. Lythrum became a garden stalwart in the mid-1800s. It bloomed in back yards for 100 years before it became invasive. We don’t know why some plants reach invader status after such a long time. It may be genetic. Plants and insects evolve over time. One genetic switch may bring a dramatic change.
 
Early on, no one foresaw the damage alien plants would do when they were free of the constraints that kept them in bounds in their native homes. But we know now, and know that we can’t predict which seemingly desirable aliens will turn into invaders. So we are faced with not only an ecological problem but also a moral one. In his excellent and heartfelt book, Bringing Nature Home, entomologist Doug Tallamy asks a thought-provoking question. We go to great lengths to quarantine and prohibit diseases that affect humans and farm animals. “Why are the native plants that sustain us and our native animals less worthy of protection?”
 
Creating habitat with native plant gardening:: another milkweed fan: a hummingbird moth (Hemaris thysbe) on common milkweed (Asclepias incarnate) in Osceola, Missouri. Photo by Betsey Crawford

Another milkweed fan: a hummingbird moth (Hemaris thysbe) on common milkweed (Asclepias incarnate) in Osceola, Missouri

Possible answers bring us back to the stories we tell ourselves. The dream of the west, and now most of the world, has been dominion. The earth is ours to subdue. Humans, or at least a select subset of them, are the undisputed lords of creation. Other humans, animals, plants, minerals all exist for the benefit of those with money and power. This is the driving force behind the destruction of the Amazon rainforest today. A milder but still deadly version drives the landscaping trade. New and more exotic plants, more lethal insecticides, billions spent on millions of acres of grass two inches high.

 The alternate dream isn’t new. It’s the dream our human consciousness emerged from: the deep knowledge that we are intimately related to everything on earth. Literally related: we share 45% of our DNA with plants and 60% with fruit flies. We share with insects the same enzymes, muscle fibers, neurons. Our hearts and brains do pretty much the same things. Our digestive and reproductive pathways are similar. Insects communicate, form communities, and work together, as we do. With infinite care, evolution has woven a web of interdependent beings to create the lush and beautiful planet we live on. Yet we are severing those miraculous bonds with increasing rapidity. All because of stories we tell ourselves about what progress or prosperity or happiness or aesthetics should look like. When we grab our shovels and replant a place for the abundance of life we are re-tying our links to the diverse world around us. And we are changing those stories.
 
White-lined sphinx moth (Hyles lineata) Gary Giacomini Open Space Preserve, Woodacre, California by Betsey Crawford

White-lined sphinx moth (Hyles lineata) Gary Giacomini Open Space Preserve, Woodacre, California

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