We humans have drained half the world’s wetlands and fully exploited or overexploited 75 percent of its fishing grounds. There are other sobering statistics our behavior has caused: every day, 130 species of plants or animals become extinct—a rate that’s probably more than a thousand times higher than the number the Earth would lose without us. Today, a full 70 percent of our plants are threatened with extinction, as well as 37 percent of freshwater fish, 35 percent of invertebrates, 30 percent of amphibians, 28 percent of reptiles, 21 percent of mammals and 12 percent of birds. By the year 2050, coral reefs—as well as the world’s polar bears—could be gone.
On December 20, 2006, the General Assembly of the United Nations declared 2010 the International Year of Biodiversity. Fourteen years before, in 1992, at the United Nations Conference on Environment and Development in Rio de Janeiro, Brazil, 154 countries signed the Convention on Biological Diversity. One of the main objectives of the convention was to conserve biological species, genetic resources, habitats and ecosystems. By declaring 2010 the pivotal year to draw the world’s attention to the necessity of safeguarding the planet’s biodiverse nature, the United Nations hoped to mobilize the public to take stronger action on the convention’s goals.
From the above statistics, however, it’s obvious that we haven’t done enough.
In some ways, it could be said that we’ve lost biodiversity by bringing in more of it—on purpose.
New Zealand, for example, has the second-highest number of introduced bird species—130—of any country in the world. A few of those newcomers were kept as caged or domestic birds, but most were deliberately set free to live in the wild. Settlers from Great Britain cleared land for farming and made it unsuitable habitat for most of the native birds. Missing the music of home, they brought over British songbirds.
And while some of New Zealand’s native birds ate insects, they would only forage in farmland if there was bush nearby. As the bush edge was pushed back for agriculture, the birds had less effect as pest-controllers. So farmers introduced thrushes, starlings, sparrows, blackbirds and magpies. Not only did these birds eat insects, they played a valuable role in pollinating flowers and dispersing native plant seeds in areas where the indigenous bird species had declined.
In my own home state of Wisconsin, black locust trees, from the slopes and forest margins of southern Appalachia and the Ozarks, were introduced in the early 1900s to stabilize shorelines. While the trees’ dense stands shaded out most native understory vegetation, their aggressive growth patterns and extensive root systems discouraged soil erosion.
The Asian lady beetle is another foreigner we welcomed into our country with open arms. Although it was imported and released as early as 1916 in attempts to naturally control certain insect pests, the beetle’s first populations were not found in the U.S. until 1988 in New Orleans. Over the years, federal, state and private entomologists have released the insect at a number of locations.
The Asian lady beetle’s natural control of aphids in pecan orchards and on some ornamental plants has decreased insecticide use. The beetles do not damage structures, do not chew or bore holes in walls, nor eat carpet or furniture. They do not lay their eggs in homes. They will, though, invade your house in large numbers.
Unfortunately, however, most of the nonnatives we introduce become invasive, and they account for 40 percent of all animal extinctions today. And those are just the extinctions we know about. Scientists say that we’ve only discovered 10 percent of the species on Earth; they estimate that there are currently approximately 13 million species on the globe, of which only 1.75 million have been identified. Who knows what effect the birds, plants, insects and animals we move in are having on them?
Is the risk of introducing a new species worth taking if you know that it will solve another environmental problem, such as soil erosion or pest control? Before you decide, consider this: if you knew a newly introduced species might just protect the last polar bear or the final orchid, what would your answer be?
Here’s to finding your true places and natural habitats,