What is the Anthropocene?

Just as we divide our lives into months and years to help us keep track of passing time, scientists divide the history of our planet into geological eras. We met some of these eras in the previous post: the Permian, the Triassic, the Cretaceous, the Paleogene.

The last post also mentioned the Holocene era. The Holocene has been going on for 10,000 years now, and it’s been very important in the history of our species. While humans essentially identical to those of us living today have been around for 200,000 years or so, human civilization – in the form of cities and farming – only arose about 8,000 years ago. Why is this?

For most of our planet’s history, living conditions have been wildly unstable. Continents moved around. Sea levels rose and fell dramatically. Glaciers advanced and retreated. Nobody could stay in one place for too long.

But all that changed in the Holocene. For thousands of years – a long time for living things, even if not much more than a blink for a planet – the climate was remarkably stable. The weather changed in a predictable way from season to season, and humans were able to learn these patterns and time their farming activities to greatly increase their chances of a successful crop. Once we were able to produce food from fixed locations, we could start living in the same place year-round – and because the oceans remained at consistent levels, we were able to build our cities along reliable shorelines.

Now, though, the stable conditions that defined the Holocene are changing. They’re changing so much that scientists have proposed labeling the present day as a brand-new geological era: the Anthropocene, the Age of Man.

A period of time gets marked off as its own geological era when it is distinctly different from surrounding time periods. Our own time is not in the geological record yet, but scientists are certain that when it is, our own activities will be clearly visible – if, several million years in the future, there is anyone around to look.

The record of our time will include evidence of the mass extinction that is already underway. It will preserve signs of increasing levels of carbon dioxide in the atmosphere, and of rising global temperatures caused by this increase. It will contain the remains of human garbage. And it will bear the imprints of how we changed the landscape by building vast cities, engaging in industrial agriculture, and destroying ancient forests.

Although the Anthropocene is not really an official geological era yet, there is no turning back from the changes that it represents. Human-scale time is cyclical: we know that March and spring will come again. But geological time goes in only one direction. The Holocene is never coming back.

What is the Anthropocene?

What are mass extinctions?

We know what extinction is: the complete and permanent loss of a species. This kind of thing is happening all the time on Earth; it’s just part of how our planet works. While it’s always sad to see a unique form of life go, the losses are usually balanced out by the appearance of new species, as organisms continue to evolve and change.

Sometimes, though, an unusually large number of extinctions happen in a relatively short period of time, in an event known as a mass extinction. Though there’s no exact definition for what counts as a mass extinction, it’s generally agreed that there have been five really big ones in the past 450 million years of our planet’s history.

The largest of these, the Permian-Triassic event, killed over 90% of the species that were living on Earth at that time. It was this massive disappearance of life that paved the way for the rise of the dinosaurs.

Because the dinosaurs are the most famous of the former inhabitants of our planet, the event that killed them – the Cretaceous-Paleogene event – is the most famous of the mass extinctions.

Scientists are still unsure what caused these relatively-sudden waves of extinction. Possible causes include naturally-occurring climate change; geological events, like volcanic eruptions; disasters originating in space, like asteroid strikes; and, in the case of the more recent extinction events, hunting by early humans.

Many scientists agree, though, that we are witnessing a major extinction event right now. The Holocene extinction has been going on since 1900, with species vanishing 1,000 times faster than they normally do. Scientists likewise agree that this is due to human activity, including human-caused climate change; deliberate killing of animals through overhunting and overfishing; widespread destruction of habitat; and introduction of non-native species, which can overwhelm and outcompete species that haven’t met them before.

This enormous loss of diversity on our planet is sad, and it is avoidable, if we choose to take action. If we choose to do nothing, the results may be catastrophic. Because of the complex ways in which we rely on other forms of life, experts say that if we continue to lose species at the current rate, we ourselves are likely to be one of the casualties.

What are mass extinctions?

Does having a natural yard make you a bad American?

Not at all.

Some people think that natural yards look messy, unattractive, and unmaintained. They take pride in mowing their lawns and pruning their shrubs, thinking that by doing so they are showing that they care for their property, and that this in turn makes them a good neighbor, a good citizen, and a good American.

But a recent book argues that America’s Founding Fathers were themselves devoted gardeners, and that the way they gardened – the way they thought about plants – bore little resemblance to the beliefs and habits of many Americans today.

Here is one particularly striking paragraph from Founding Gardeners: The Revolutionary Generation, Nature, and the Shaping of the American Nation, written by Andrea Wulf, and published in 2012:

“By the time Jefferson became president, many trees had been lost [in Washington DC, which at the time was still more of a wilderness than a city]. Most shocking of all, those on the grounds of the White House had been felled by Federalists* after the accession of the Republicans, one observer noted, ‘out of spite to them who cherished it.’ Enraged by Jefferson’s election, so the rumor went, his rivals had ordered the ancient trees to be cut down as a parting gesture, knowing how such vandalism would wound the new president, who regarded tree-felling as ‘a crime little short of murder.’ Jefferson was so furious at this unscrupulous destruction that shortly after he moved into the White House, the author of the Declaration of Independence was overheard making the rather surprising comment, ‘I wish I was a despot that I might save the noble, the beautiful trees that are daily falling.'” (page 148)

(*Jefferson was a member of the Republican Party, as it existed in his day. The opposing political party – of which departing President John Adams was a member – was called the Federalists.)

And here are some other fascinating facts from the book:

Many of the most important figures in the founding of America had strong feelings about the importance of gardening. The first four presidents of the United States – George Washington, John Adams, Thomas Jefferson, and James Madison – all couldn’t wait to retire from politics and go back to working on their farms, vegetable plots, and ornamental gardens.

The “Founding Gardeners” understood the importance of nature. The fourth President, James Madison – the person after whom Madison, Wisconsin is named – was the first major figure to publicly call for an end to deforestation in America.

In the opinion of the “Founding Gardeners”, conventional yards are un-American. Jefferson and Adams, while serving as ambassadors in Europe, observed that many people there were turning away from a formal style of gardening, seeing straight paths, pruned trees, and geometrical hedges as too dictatorial. These landowners thought that a free people should embrace a more natural look in their gardens. In other words, Americans who value independence and democracy should show it by letting garden plants follow their natural life courses.

The “Founding Gardeners” believed that native plants make America great. At his estate at Mount Vernon, Washington planted trees and shrubs from all over the thirteen states, but he did not allow any plants from Europe in his gardens. And, while some Europeans disparaged America by saying that the wildlife there was inferior, Jefferson sent samples demonstrating that the New World had bigger animals and more beautiful plants.

Being a good American means having a yard that reflects the natural plant communities of America. Being a good American means letting plants have their own life, liberty, and pursuit of vegetative happiness, rather than constantly imposing our own will on them.

America invented the idea of national parks. Having nature in our yards shows that we share the longstanding American values of respecting and conserving our natural environment.

Does having a natural yard make you a bad American?

How do I know what plants are native?

So you’ve decided to garden with native plants. Great! But… which plants, exactly, should you put in your yard? What is native?

The concept of nativeness encompasses two aspects: space, and time. First, where was the plant in question found before humans started moving it to new places? Many resources will answer this question by noting whether a certain plant species was historically found in a particular state. But this is a somewhat arbitrary criteria. Plants don’t know or care about the political constructs we call states. And large states may contain many diverse ecosystems. A species might naturally occur in the forests of northern California, but that doesn’t make it a suitable choice for a yard in the arid southern part of the state.

This is why some resources list native plants by county. But even this doesn’t really have anything to do with the way plants naturally distribute themselves. A plant that has historically lived just over the county line might be a better fit for a site than a plant found in a distant corner of the same county.

For this reason, some native gardeners skip native-by-county and native-by-state lists entirely, and instead look at distance. Any reputable dealer of native plants will be able to tell you where they got the original seed from. (And it should be seed. Reputable dealers do not sell plants taken from the wild; they propagate seeds in their nurseries and sell those plants.) If that naturally-occurring source of seed is within, say, 50 miles of the intended planting site, then the species is native. If the seed is being collected from further away, it is not native, and won’t be considered for that particular garden.

The other aspect of nativeness is time. When we say that a species was found somewhere historically, what do we mean? Kentucky bluegrass, which originally evolved in Europe, could be found across the eastern United States 100 years ago. Does that make it native? What about plants that lived in the northern states prior to the last ice age, got wiped out by the glaciers, and haven’t come back on their own yet? Are they native?

Most people say that if a species was found in a place just before the time that Europeans got there, then it is historically native. But as climate change continues to alter ecosystems, we may want to update our definition of historically native to mean “species that were found in that place when the local climate was similar to what it will be again in the near future”.

Many native gardeners are not purists – that is, they will plant a non-native species in their yards because the species has especially beautiful flowers, or produces delicious fruit, or simply is a personal favorite of the gardener. There is nothing wrong with this. But if we are serious about native gardening, we should at least be aware when a species we are planting is one of these special exceptions. To do so, we first must decide how we are defining what is or is not native in our own yards.

How do I know what plants are native?

What is Kentucky bluegrass?

Everybody knows Kentucky bluegrass. It’s that good American plant that people across the country use in their lawns.

But wait – is Kentucky bluegrass really American?

It turns out it isn’t.

Kentucky bluegrass is scientifically known as Poa pratensis, which means “meadow grass”. That was the plant’s common name centuries ago in its native range – in Europe.

Meadow grass was brought to North America in the 1600s, probably by accident. It was a happy accident from the settlers’ point of view, since meadow grass made great forage for cattle. North America’s native grasses, the pioneers quickly discovered, couldn’t survive being eaten by cows day after day.

In addition to being good at surviving constant grazing, meadow grass – which soon was being referred to as “Old World meadow grass” – was also good at spreading. The plant rapidly escaped from pastures in the East Coast colonies, and started heading west. When explorers finally made it over the Appalachians to the region now known as Kentucky, they found the meadow grass had beaten them there. From its ability to travel swiftly and its deep green color, the plant acquired its modern name, “Kentucky bluegrass”.

Why do we use this invasive grass species in our lawns? After all, North America boasts over 1,000 of its own native grass species. The answer is that, for the same reason that North American grasses don’t put up with grazing, they also don’t survive regular mowing.

Kentucky bluegrass, and other European species, evolved alongside grazing animals that tended to stay put. These species needed to figure out strategies to recover from daily munching.

North American species, in contrast, evolved alongside buffalo – and as we all know, buffalo roam. Therefore, North American grass species evolved to survive being occasionally descended upon by a herd of large ungulates, and then having plenty of time to grow back before the animals returned for another meal. In the context of a yard, these species can tolerate being mowed once in a rare while, but they quickly die if mowed every week.

For a period of our country’s history, many people thought that being a good American meant having a yard filled edge to edge with an invasive grass species. Now, many people think that being a good American means celebrating our own native plants – and one way we can do that is to invite them into our yards.

What is Kentucky bluegrass?

Why are lawns seen as safe?

If lawns are so dangerous, why do so many people believe they are safe? One reason is that advertisers have spent decades telling us that lawns are safe.

In the post-war period, lawns actually were marketed to women. Advertisements persistently positioned lawns as a kind of outdoor extension of the living room. (This is why lawns are so often compared to carpets.) Lawns were depicted as safe, clean places for children to play, and women were told that not having a nicely-mowed lawn was akin to letting garbage pile up inside their homes or failing to cook dinner for their families. So, wives nagged their husbands to mow their lawns, and lawns continued to serve as a visual symbol, without regard to what they actually did to people and the environment.

As described before, people tend to perceive familiar things as safe. At one time, lawns were not common, and most people didn’t know why they would want one – lawns took a lot of work to maintain, and didn’t seem to provide anything in exchange. But as lawns became more common – driven by social pressure, which in turn was driven by images and meanings created by advertising – lawns and their accompanying equipment became normal parts of the suburban scene. People forgot that these things were dangerous, and stopped following safety precautions. More recent generations, who grew up with lawns, may have never been aware of the hazards just outside their home.

But industries haven’t forgotten. Pesticide manufacturers know that their products are dangerous. Lawnmower manufacturers know that their products are dangerous. These industries quietly lobby against bans and regulations on their products, while investing heavily in advertising to tell us that it is insects and tall grass that are the real dangers. In fact, there is very little evidence to support those claims.

Our brains have evolved shortcuts for assessing risk – shortcuts that don’t always work in the modern world, and that can be manipulated by what special interest groups tell us. By paying attention to where information is coming from, and by looking at the real facts regarding risk, we can make intelligent decisions about how to keep ourselves and our families safe.

Why are lawns seen as safe?

What’s new in natural yards? January 2018

A candidate in this year’s Wisconsin gubernatorial race has named lawns as an issue he would address if elected. In a post on his campaign website, Jeff Rumbaugh says that if he becomes the governor, he will not ban lawns, but will work with municipalities to make alternative forms of gardening more accessible to property owners.

As a reason for this position, Rumbaugh focuses on the wasteful water consumption associated with lawns. He also mentions the connection between lawns and climate change, and the amount of work involved in maintaining a lawn. He proposes wildflower plantings, vegetable gardens, and gravel as more environmentally-responsible kinds of yards.

Rumbaugh’s campaign promise follows California’s statewide restrictions on lawns – effective as of December 2015 – and Madison’s easing of its regulations on natural yards. Meanwhile, a governmental task force in Delaware has recommended phasing out the use of non-native plants, which currently make up more than 70% of the plants sold at garden centers around the state.

Evidence is gathering that the era of the lawn as a dominant element in American landscaping is at an end. Natural yards are likely to become much more common over the next several years. There is still time for savvy homeowners to be part of this mainstream movement, rather than being the last on their block to adopt new gardening practices.

 

That Blog does not endorse political candidates. This post is simply a commentary on the continuing emergence of lawns as a political issue.

What’s new in natural yards? January 2018