Grassland Rewrite

Greetings!  The following is a rewrite of samples 23, 24, and 25, which were originally posted way back in 2019, when I was young and innocent.  The revised version is shorter, clearer, and adds new factoids.  I hope that as my editing process moves into newer sections, fewer tweaks will be needed, and the blessed finish line will arrive before the sun burns out.

MOTHER GRASSLAND

The family of life is solar powered.  Incoming solar energy is received by green plants, who use it to produce sugar.  This process is photosynthesis.  It converts solar energy into a form of chemical energy that plants and animals must have to survive.  Animals acquire this energy by eating plant material, or by dining on plant-eating animals. 

Photosynthesis splits water molecules (H₂O) into hydrogen and oxygen atoms.  Then, in a fancy magic act, hydrogen is stirred together with CO₂ to make a sugar called glucose (C₆H₁₂O₆).  The process results in some leftover oxygen atoms, which are released to the atmosphere.  Notice that animals exhale the CO₂ needed by plants, and plants exhale the oxygen needed by animals, a sacred circle dance.  Plants use the sugar to fuel their daily life, or they can convert it to starch, and save it for later.  Plants can also make fat, protein, and vitamins.  They’re much smarter than they look.

The act of snatching carbon from the air, and incorporating it into living plant tissues, is called carbon fixation, or carbon sequestration.  As more carbon gets sequestered into the plants and surrounding topsoil, then less of it remains in the atmosphere.  This is great, because too much carbon in the atmosphere can lead to catastrophic climate juju, like the freaky changes that are beginning to bludgeon the family of life right now.

There are four primary terrestrial biomes: grassland, forest, desert, and tundra.  Grasslands are communities of different plants — primarily grasses, mixed with a wide variety of sedges and leafy forbs (wild flowers and herbs).  These mixed communities maximize the capture of solar energy, make better use of soil resources, and create rich humus.  Humus boosts soil fertility, and helps retain moisture.  Some plants also convert atmospheric nitrogen into a form that is essential for all living things.  Others are good at retrieving essential mineral nutrients.

There are maybe 12,000 species of grass, and they grow in many tropical and temperate regions.  Some are able to survive extended droughts, or long winters.  Grasslands have two modes, productive and dormant.  In warm climates, they are dormant during the dry season, and recover when the rains return.  In temperate climates, they are dormant during the frosty months, and green when the soil thaws. 

Following an intense disturbance, grasslands can recover in 5 to 10 years — far faster than a wrecked forest.  Evolution has done a remarkable job of fine-tuning grasslands for rugged durability.  They can recover more easily after wildfires because only a third of grassland biomass is above ground, and most vulnerable to flames.  Plants send roots far underground, to acquire moisture and nutrients.  Some roots grow as deep as 32 feet (10 m).  The seeds of many grassland species can remain dormant for an extended period, postponing germination until appropriate conditions return.  Some seeds can survive a hot and slippery ride through an herbivore’s gut and remain fertile, enabling the colonization of new locations.

Grass and Herbivores

Grassland communities run on carb energy that moves from species to species, up and down the food chain, and enables the existence of the family of life.  Large grass eating herbivores were a favorite source of nutrients for our prehistoric ancestors.  For the effort invested in hunting, they provided the biggest jackpots of meat.  Our strong desire for these animals, and our ongoing dependence on them, eventually resulted in some hominins evolving into Homo sapiens, the last surviving hominin species.

It’s important to understand that herds of large herbivores do not usually reside in forests or jungles.  Large body size can be an important advantage on grasslands, but a disadvantage in dense woodlands.  In terms of vegetation, forests contain much more plant biomass than grasslands, but most of it is elevated out of the reach of hungry herbivores.  On the other hand, grasslands annually produce much more new biomass per acre than forests, and it’s conveniently located close to the ground.

To herd critters, grassland looks like a candy store where all the goodies are free and delicious.  Grasslands are the best place to dine on high quality greenery, hang out with friends and relatives, produce cute offspring, and enjoy a wonderful life of fresh air, travel, and adventure.  Consequently, grasslands are home to far more large animals.  I would expect that most land-dwelling megafauna species originated in grasslands.

Grass and Hominins

The Miocene Epoch spanned from 23 to 5.3 million years ago.  It seems that the early Miocene was wet and warm, and many ecosystems were forests.  Much of Antarctica was covered with temperate forest 20 million years ago.  Later, maybe six to eight million years ago, it got cooler and dryer, and a different type of ecosystem evolved and expanded — grasslands.  Compared to forests, grasslands generally need less precipitation to survive.  Today, the Earth’s forest area is 80 percent smaller than it was in the Miocene’s golden age of trees.

This transition had a significant impact on the human saga.  As forests shrank, there was less habitat for our tree-dwelling ancestors.  A number of forest species tumbled off the stage forever.  Some primates moved onto the savannah, and figured out how to survive as ground-dwelling primates, in open country.  They included the ancestors of baboons and humans.  Humans are hominins, primates that walk on two legs.  About four million years ago, hominins originated on the savannah grasslands of tropical Mother Africa. 

Our tree-dwelling ancestors were primarily frugivores, fruit eaters.  They ate stuff that grew or lived in trees.  When they became ground-dwelling critters, they needed a new diet.  Large herbivores became a popular choice.  Hunting was the path to success, and grassland was the place to be.  Consequently, as humans migrated out of Africa, and colonized the world, they preferred to select routes that majored in grasslands.  Their journey took them to grasslands in the Middle East, and then Europe. 

Barry Cunliffe noted that a vast steppe grassland began in Hungary and ended in Manchuria, providing a grassy highway that was 5,600 miles (9,000 km) long.  As an added bonus, the steppe was largely carpeted with vegetation that was drought-resistant and frost-tolerant.  Once established in northern Asia, intrepid pioneers were eventually able to wander from Siberia, over the Beringia land bridge, and then explore the incredible Serengetis of the Americas.

In 1872, Kansas senator John James Ingalls celebrated the power of grass.  He wrote: “Grass is the forgiveness of nature — her constant benediction.  …Streets abandoned by traffic become grass-grown like rural lanes, and are obliterated.  Forests decay, harvests perish, flowers vanish, but grass is immortal.  …The primary form of food is grass.  Grass feeds the ox: the ox nourishes man: man dies and goes to grass again; and so the tide of life with everlasting repetition, in continuous circles, moves endlessly on and upward, and in more senses than one, all flesh is grass.”

Super Grass

And now, the plot thickens.  There are several ways that photosynthesis fixes carbon in plants.  The conventional process is called C₃.  It produces a compound that has three carbon atoms.  The turbocharged process is C₄, and it produces a compound that has four carbon atoms.  Maybe 85 percent of the plant species on Earth are C₃.  Their method of carbon fixation is simpler and less efficient than C₄.  Both types are very old, but when climate change favored the expansion of grassland, C₄ species got an important boost.

Elizabeth Kellogg studied C₄ plants.  In one experiment she found that, under ideal conditions, C₃ plants could theoretically capture and store up to 4.6 percent of the solar energy they received, while C₄ plants could get up to 6 percent (30 percent more).  In other words, provided with the same inputs of sunlight and water, C₄ produces more calories than C₃ — carbs that fuel the family of life.  They also produce more root biomass, which increases their tolerance for drought and fire.

Kellogg calls the C₄ process a turbocharger.  While only 3 percent of flowering plant species are C₄, they account for 23 percent of all carbon fixation in the world.  Of the 12,000 grass species, 46 percent of them are C₄, and they include corn (maize), sugar cane, millet, and sorghum.  (Mad scientists are now trying to alter DNA to make rice C₄ too.)

There are four conditions under which C₄ plants have a big advantage — high temperature, high light, low moisture, and low nutrients.  Because they need less water, C₄ plants better conserve soil moisture, so their growing season is longer in arid regions.  Kellogg wrote, “In the last 8 million years, C₄ grasses have come to dominate much of the earth’s land surface.” 

C₃ grasses are better adapted to moist forest floors and limited sunlight.  They are less able to thrive in arid grasslands.  Out on the savannah, C₄ grasses enjoy some important advantages.  When conditions are right, they are able to manufacture generous amounts of chemical energy (sugar), and this increases their odds for survival.

[Important!]  The big picture here is that climate change radically altered the family of life.  It encouraged the substantial expansion of grassland, which boosted the expansion of C₄ grasses, which propelled the evolution and expansion of large grazers and carnivores, which boosted the global tonnage of living meat, which set the stage for the arrival of our hominin ancestors.  Today’s climate crisis seems likely to unleash far bigger changes in something more like the blink of an eye.

Grasslands can support more large animals than forests.  Grassland megafauna migrated and settled on five continents (not Australasia).  Around the world we find varieties of horses, bison, elephants, antelope, deer, hyenas, wolves, bears, and so on.  Grasslands support far less biodiversity than rainforests, which are home to fantastic numbers of different species.

Graham Harvey, a grass worshipping wordsmith, noted that growth is actually stimulated by grazing and fire.  In a brilliant design, new blades of grass emerge from growing points located close to the ground, where they are less likely to be damaged by hungry teeth or passing flames.  The faster that grasses can send up new blades, the more sunlight they can capture, the more sugar they can make, and the happier the whole ecosystem becomes.  Joy!

Another benefit of grazing is that herbivores often nip off the rising shoots of woody vegetation.  If trees and brush were allowed to grow and spread, they would compete for sunlight with the grasses.  Then, the herds of hungry herbivores would have less to eat, and so would the carnivores that adore red meat.  Herds religiously offered their deep gratitude to the grass people by lovingly depositing nutrient rich manure and urine all over the place.

Grass eaters are called grazers.  Browsers are critters that eat leaves, woody shoots, bark, and saplings.  Some species are both.  The elephant family loves to dine on young green leaves, and they sometimes knock trees down to get them.  Each day, elephants eat 550 pounds (250 kg) of grass and leaves, and then turn it into magnificent fertilizer.  Giraffes are top feeders that specialize in leafy vegetation that elephants and rhinos are too short to snatch.

Browsers can limit the expansion of trees and woody brush, but they aren’t fanatical mass murdering exterminators.  Savannah ecosystems are grasslands dotted here and there with trees and shrubs.  Grass provides food for the grazing herds, and woody vegetation nourishes the browsers — and it provides shade and hiding places.  Home sweet home!

Harvey concluded that, in many ways, humans are creatures of grass country, like the bison, hyenas, and vultures.  We still are.  We take immense pride in the brilliant triumph of humankind, but if we turn off the spotlights and loudspeakers, and pull back the curtains, we see that the Green Mother of this grand and goofy misadventure is our intimate and enduring dependence on grassland ecosystems.  Grass is Superman’s momma.

Manmade Grassland

All flesh is grass, but grass is not limitless.  In the old days, there were no hunting licenses, rules, bag limits, or game wardens.  The hunting fad was able to grow until it eventually smashed into rock solid limits.  Flesh is not limitless.  Folks began missing dinners, and going to bed with growling tummies.  Overshoot is never sustainable.  Too many hominins spoil the party.  The 100% guaranteed, always effective, least popular cure for overshoot is die-off.

Another cure is migration, pack up and move.  This medicine worked for thousands of years, as folks colonized the regions uninhabited by humans.  Eventually, the happy hunters learned a painful new lesson: Earth is not limitless.  Shit!  What now?  Cultural taboos that limited reproduction could provide some pressure relief.  So could perpetual inter-tribal warfare, bloody the competition whenever possible.  Cleverness is the persistent gift and curse of humankind.  It conjured another idea, a magic wand call the firestick.

Shortgrass prairie grassland needs between 10 and 30 inches (25 to 76 cm) of annual precipitation.  Most of its plants are less than one foot (30 cm) tall.  Tallgrass prairie needs more than 30 inches (76 cm) of annual precipitation.  In tallgrass, prairie plants can sometimes grow up to 13 feet (4 m) high — tall enough to hide a horse.  Tallgrass can produce far more food for grazing animals, which enables larger herds.  However, the precipitation needed by tallgrass is also adequate for the survival of forest.  While browsing and grazing helps to maintain open grassland, it’s not enough to fully prevent the existence and spread of forest. 

When Big Mama Nature gets in a stormy mood, she sometimes ignites wildfires with lightning bolts.  Fire can be a good tonic for the health of grass.  It burns up accumulated dead foliage and debris, allowing more solar energy to empower the grass people.  Also, with the dead junk burned away, the exposed ground warms up faster when the snows melt, enabling the growing season to begin earlier.  Soon after fires end, tender green shoots emerge from the ashes.  Fresh greenery looks heavenly to the grazing critters, and hunters love grazing critters. 

Jill Haukos noted that fire happily stimulates the growth of fresh new grass, but it has zero concern for the health and safety of trees and shrubs.  Grass productivity is 20 to 40 percent higher on burned land, compared to unburned.  When tallgrass prairie is deliberately burned every few years, it will not transition to forest, because the seeds, sprouts, and saplings can’t survive the cruel abuse.  Natural wildfire doesn’t faithfully follow regular burn schedules, but regular manmade fire is able to trump the tree people.

Wild folks clearly understood that maintaining extensive grasslands improved their hunting.  By deliberately controlling nature, they could eat better, and feed more bambinos.  So they did.  For hunters, fire was a powerful beneficial servant.  For the rodents, birds, and insects of the grassland, fire could be a viciously powerful master.  Shepard Krech mentioned that when the first humans settled Hawaii and New Zealand, they cleared the land with fire, driving many bird species extinct.  Is it OK to rubbish a thriving ecosystem for selfish reasons?  Only human desires matter?

Haukos wrote about bison grazing in tallgrass prairie.  Hungry herds have little interest in seeking un-grazed locations that are covered with lots of old and skanky low calorie grass.  They much prefer fresh new grass, and they pay close attention to recently burned landscapes.  “Bison maintain large grazing lawns.  They return again and again to the same ‘lawns’ to eat the new growth of grass, which is highly nutritious.  These areas may look overgrazed but actually have new growth continually, providing the nutritious grass bison need, even if only one inch high (2.5 cm).”

The practice of using periodic burns to maintain and expand superb grazing land is often called firestick farming, because it uses burning to increase the harvest of life-giving meat.  It is a powerful, easy, low tech way to benefit large game.  Alfred Crosby noted that firestick farming had transformed much of six continents long before the first field was planted.  Let’s look at a few examples.

North America

The chilly Pleistocene ended about 11,700 years ago, with the arrival of the warmer and gentler Holocene era that we currently enjoy.  Ice sheets melted and retreated, creating space for tundra.  As the climate further warmed, expanding prairies displaced regions of tundra.  Prairie ecosystems can support more complex biodiversity, as different communities of species adapt to different mixes of soil types, moisture, and climate.  Where changing conditions favored the existence of trees, forest expanded.  Forests tend to trump grassland, because they allow less sunlight to reach the ground.  Once established, a forest can thrive for thousands of years, if not molested by murderous terrorists.

One way or another, Native Americans learned the benefits of grass burning.  They understood that regular burning could inhibit forest regeneration.  As centuries passed, tallgrass regions expanded, much to the delight of large herbivores, and hungry hunters.

Stephen Pyne wrote that when white colonists were settling in the eastern U.S., the western portion of the Great Plains was shortgrass prairie, too dry to support forest.  But much of the eastern portion was tallgrass prairie.  It had rainfall and soils suitable for forest, but over the centuries, Native Americans had gradually pushed back forest territory to greatly expand the prairie.  They maintained this highly productive prairie by burning it every few years, to kill young saplings.  It provided excellent habitat for bison and other delicacies.

Burning was a common practice in many regions of North America.  By A.D. 1000, the expansion of manmade tallgrass prairie had enabled bison to migrate east of the Mississippi River watershed for the first time.  By the 1600s, several million bison lived in a region spanning from Massachusetts to Florida. 

Shepard Krech wrote that along the east coast, there were oak openings (meadows with scattered trees) as large as 1,000 acres (404 ha).  Manmade grasslands in the Shenandoah Valley covered a thousand square miles (2,590 km²).  He noted that Indian fires sometimes had unintended consequences, when they exploded into raging infernos that burned for days, sometimes killing entire bison herds, up to a thousand animals. 

Lamar Marshall described the relationship between the Cherokee people and the bison.  The tribe resided east of the Mississippi River, and lived by farming and hunting.  Legends suggested that bison did not live there until sometime around A.D. 1400.  By then, the natives had significantly expanded grassland for hunting, and cleared forest for farming.  Game was especially attracted to rivercane pastures (canebrakes) that were burned every 7 to 10 years.  Marshall provided a map showing how huge North America’s bison range was in 1500. [Look]

Michael Williams noted that as the diseases of civilization spread westward, Indians died in great numbers.  They had zero immunity to deadly and highly contagious Old World pathogens.  Diseases spread westward far faster than the expansion of settlers.  Consequently, the traditional burning was sharply reduced, and forests were returning.  In 1750, they may have been bigger and denser than they had been in the previous thousand years.  When whites eventually arrived to create permanent agricultural communities, the happy regrown forests had to be savagely euthanized.

Arlie Schorger wrote about the vast manmade tallgrass prairies of southern and western Wisconsin, and the last bison killed there in 1832.  Some prairies spanned 50 miles.  Prairie was almost continuous from Lake Winnebago to the Illinois border.  Natives had been expanding and maintaining grassland for a very long time.  In 1767, white visitors observed “large droves of buffalos” on the fine meadows along the Buffalo River. 

By and by, devastating epidemics hammered the indigenous people who had maintained the grassland and hunted the bison.  Regular burning sputtered out.  The last bison seen crossing the Mississippi River, and entering Wisconsin, was in 1820.  By 1854, dense groves of 25 year old trees were joyfully reclaiming their ancestral homeland.  Unfortunately, these recovering forests had a bleak future, because they stood directly in the path of a rapidly approaching mob of merciless pale-faced axe murderers.  Shit!

Over the passage of centuries, the tallgrass prairies created topsoil that was deep and remarkably fertile.  Then came the settlers, with their plows and ambitions.  Plows are magnificent tools for destroying soil, and creating permanent irreparable damage.  Walter Youngquist wrote, “In the United States, half the topsoil of Iowa is now in the Mississippi River delta.”  Today, tallgrass prairie ecosystems are in danger of extinction, maybe one percent of them still survive.  Exotic freak show grasses like corn and wheat are far more popular and profitable than the indigenous tallgrass.

In his book Collapse, Jared Diamond mentioned his visit to a wee remnant of the ancient prairie that had somehow survived the plowman invasion, an old churchyard in Iowa.  It was surrounded by land that had been farmed for more than 100 years.  He wrote, “As a result of soil being eroded much more rapidly from fields than from the churchyard, the yard now stands like a little island raised 10 feet (3 m) above the surrounding sea of farmland.”

Australia

Bill Gammage described the Australia that British colonists observed in 1788, when they first washed up on shore.  That landscape was radically different from what it is today.  Early white eyewitnesses frequently commented that large regions looked like parks.  In those days, all English parks were the private estates of the super-rich.  Oddly, the Aborigines who inhabited the beautiful park-like Australian countryside were penniless illiterate bare-naked Stone Age antifascist anarchist heathens.  Their wealth was their time-proven knowledge.

In 1788, large areas of Australia had been actively managed by firestick farming, which greatly promoted habitat for the delicious critters that the natives loved to have lunch with.  The Aborigines used both hot fires and cool fires to encourage vegetation that was fire intolerant, fire tolerant, fire dependent, or fire promoting.  Different fires were used to promote specific herbs, tubers, bulbs, or grasses.  When starting a fire, the time and location was carefully calculated to encourage the desired result.  According to Gammage, most of Australia was burnt about every one to five years.  On any day of the year, a fire was likely burning somewhere.

The natives generally enjoyed an affluent lifestyle.  They had learned how to live through hundred-year droughts and giant floods.  No region was too harsh for people to inhabit.  Their culture had taboos that set limits on reproduction and hunting.  During the breeding seasons of important animals, hunting was prohibited near their gathering places.  Lots of food resources were left untouched most of the time, a vital safety net.  The Dreaming had two rules: obey the Law, and leave the world as you found it.

The white colonists were clueless space aliens.  Their glorious vision was to transfer a British way of life to a continent that was highly unsuited for it.  Australia’s soils were ancient and minimally fertile, and the climate was bipolar — extreme multi-year droughts could be washed away by sudden deluges.  But, they brought their livestock and plows and gave it a whirl.  They believed that hard work was a virtue.  The Aborigines were astonished to observe how much time and effort the silly newcomers invested in producing the weird stuff they ate.

The new settlers wanted to live like proper rural Brits — permanent homes, built on fenced private property.  They freaked out when the natives set fires to maintain the grassland.  Before long, districts began banning these burns.  This led to the return of saplings and brush.  So, in just 40 years, the site of a tidy dairy farm could be replaced by dense rainforest.

Without burning, insect numbers exploded.  Without burning, fuels built up, leading to new catastrophes, called bushfires.  The Black Thursday fire hit on February 6, 1851.  It burned 12 million acres (5 million ha), killed a million sheep, thousands of cattle, and countless everything else.

Mark Brazil shared a story that was full of crap.  In Britain, cow manure was promptly and properly composted by patriotic dung beetles, which returned essential nutrients to the soil.  In Australia, none of the native dung beetles could get the least bit interested in cow shit.  It was too wet, and too out in the open.  Cow pies could patiently sit on the grass unmolested for four years, because nobody loved them.  This deeply hurt their feelings.  Adding insult to injury, Brook Jarvis noted that fussy cattle refused to graze in the vicinity of neglected pies, so the herd needed access to far more grazing land than normal.

Australian flies, on the other hand, discovered that cow pies made fabulous nurseries for their children.  Each pat could feed 3,000 maggots, which turned into flies — dense clouds of billions and billions of flies — which the hard working Christians did not in any way fancy.  Being outdoors was hellish.  In the 1960s, folks imported British dung beetles, which loved the taste and aroma of cow pies.  Oddly, this is one example where an introduced exotic species apparently didn’t create unintended consequences.  When they ran out of pies to eat, the beetles simply died.

Anyway, a continent inhabited by Stone Age people was substantially altered by firestick farming and hunting.  The Australia of 1788 was radically different from when the first humans arrived.  We’ll never know if continued firestick farming would have eventually led to severely degraded ecosystems.  Some serious imbalances can take a long time to fully develop.  Many attempts to deliberately control and exploit ecosystems have spawned huge unintended consequences over time.  The ultra-conservative indigenous kangaroos and wallabies were not control freaks, they simply adapted.

Gammage was fond of the Aborigines, because they were highly successful at surviving for a long time in a challenging ecosystem.  He was much less fond of the British colonists who, with good intentions, combined with no wisdom, were highly successful at rubbishing it. 

Baz Edmeades viewed the entire Australian experience through ecological glasses.  Fire reshaped the continent.  When humans first arrived, the north coast was home to dry forests that majored in araucaria trees.  Before long, they were displaced by fire-promoting forests that majored in eucalypts.  The original dry forests went up in smoke.  Extremely low-tech Stone Age people substantially altered the ecosystem.  We may never have a clear understanding of the early extinctions of the vertebrate megafauna and giant reptiles.