Catch the Buzz: Cities Support BioDiversity

Researchers at UCSB’s NCEAS compile the largest global dataset of urban birds and plants, which shows world’s cities retain a unique natural palette The rapid conversion of natural lands to cement-dominated urban centers is causing great losses in biodiversity. Yet, according to a new study involving 147 cities worldwide, surprisingly high numbers of plant and animal species persist and even flourish in urban environments — to the tune of hundreds of bird species and thousands of plant species in a single city.

Contrary to conventional wisdom that cities are a wasteland for biodiversity, the study found that while a few species — such as pigeons and annual meadow grass — are shared across cities, overall the mix of species in cities reflects the unique biotic heritage of their geographic location. The findings of the study conducted by a working group at UC Santa Barbara’s National Center for Ecological Analysis and Synthesis (NCEAS) and funded by the National Science Foundation were published today in the Proceedings B, a journal of the Royal Society of Biological Sciences. “While urbanization has caused cities to lose large numbers of plants and animals, the good news is that cities still retain endemic native species, which opens the door for new policies on regional and global biodiversity conservation,” said lead author and NCEAS working group member Myla F. J. Aronson, a research scientist in the Department of Ecology, Evolution and Natural Resources at Rutgers, The State University of New Jersey.

The study highlights the value of green space in cities, which have become important refuges for native species and migrating wildlife. This phenomenon has been named the Central Park Effect because of the surprisingly large number of species found in New York’s Central Park, a relatively small island of green within a metropolis. Unlike previous urban biodiversity research, this study looks beyond the local impacts of urbanization and considers overall impacts on global biodiversity. The research team created the largest global dataset to date of two diverse taxa in cities: birds (54 cities) and plants (110 cities). Findings show that many plant and animal species, including threatened and endangered species, can flourish in cities, even as others decline or disappear entirely.

Cities with more natural habitats support more bird and plant species and experience less loss in species as the city grows. Overall, cities supported far fewer species (about 92 percent less for birds and 75 percent less for native plants) than expected for similar areas of undeveloped land. “We do pay a steep price in biodiversity as urbanization expands,” said coauthor Frank La Sorte, a research associate at the Cornell Lab of Ornithology. “But even though areas that have been urbanized have far fewer species, we found that those areas retain a unique regional flavor. That uniqueness is something that people can take pride in retaining and rebuilding.” Conserving green spaces, restoring native plant species and adding biodiversity-friendly habitats within urban landscapes could, in turn, support more bird and plant species. “It is true that cities have already lost a substantial proportion of their region’s biodiversity,” said Madhusudan Katti, a faculty member in the Department of Biology at California State University, Fresno. “This can be a cup half-full or half-empty scenario. If we act now and rethink the design of our urban landscapes, cities can play a major role in conserving the remaining native plant and animal species and help bring back more of them.”

The human experience is increasingly defined within an urban context, the authors noted. They maintain it is still possible for a connection to the natural world to persist in an urban setting, but it will require planning, conservation and education. “Given that the majority of people now live in cities, this group’s synthesis of data on plant and urban plant and animal diversity should be of broad interest to ecologists as well as urban and landscape planners,” said Frank Davis, NCEAS director.

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Monarch Butterflies and Bees – We Need You!

This (slightly scary) article about Monarchs and Bees can be a good reminder of how important it is to grow native plants to create and maintain pollination opportunities for our important pollinators.

The Year the Monarch Didn’t Appear
Published: November 22, 2013

On the first of November, when Mexicans celebrate a holiday called the Day of the Dead, some also celebrate the millions of monarch butterflies that, without fail, fly to the mountainous fir forests of central Mexico on that day. They are believed to be souls of the dead, returned.

This year, for or the first time in memory, the monarch butterflies didn’t come, at least not on the Day of the Dead. They began to straggle in a week later than usual, in record-low numbers. Last year’s low of 60 million now seems great compared with the fewer than three million that have shown up so far this year. Some experts fear that the spectacular migration could be near collapse.

“It does not look good,” said Lincoln P. Brower, a monarch expert at Sweet Briar College.

It is only the latest bad news about the dramatic decline of insect populations.

Another insect in serious trouble is the wild bee, which has thousands of species. Nicotine-based pesticides called neonicotinoids are implicated in their decline, but even if they were no longer used, experts say, bees, monarchs and many other species of insect would still be in serious trouble.

That’s because of another major factor that has not been widely recognized: the precipitous loss of native vegetation across the United States.

“There’s no question that the loss of habitat is huge,” said Douglas Tallamy, a professor of entomology at the University of Delaware, who has long warned of the perils of disappearing insects. “We notice the monarch and bees because they are iconic insects,” he said. “But what do you think is happening to everything else?”

A big part of it is the way the United States farms. As the price of corn has soared in recent years, driven by federal subsidies for biofuels, farmers have expanded their fields. That has meant plowing every scrap of earth that can grow a corn plant, including millions of acres of land once reserved in a federal program for conservation purposes.

Another major cause is farming with Roundup, a herbicide that kills virtually all plants except crops that are genetically modified to survive it.

As a result, millions of acres of native plants, especially milkweed, an important source of nectar for many species, and vital for monarch butterfly larvae, have been wiped out. One study showed that Iowa has lost almost 60 percent of its milkweed, andanother found 90 percent was gone. “The agricultural landscape has been sterilized,” said Dr. Brower.

The loss of bugs is no small matter. Insects help stitch together the web of life with essential services, breaking plants down into organic matter, for example, and dispersing seeds. They are a prime source of food for birds. Critically, some 80 percent of our food crops are pollinated by insects, primarily the 4,000 or so species of the flying dust mops called bees. “All of them are in trouble,” said Marla Spivak, a professor of apiculture at the University of Minnesota.

Farm fields are not the only problem. Around the world people have replaced diverse natural habitat with the biological deserts that are roads, parking lots and bluegrass lawns. Meanwhile, the plants people choose for their yards are appealing for showy colors or shapes, not for their ecological role. Studies show that native oak trees in the mid-Atlantic states host as many as 537 species of caterpillars, which are important food for birds and other insects. Willows come in second with 456 species. Ginkgo, on the other hand, which is not native, supports three species, and zelkova, an exotic plant used to replace elm trees that died from disease, supports none. So the shelves are nearly bare for bugs and birds.

Native trees are not only grocery stores, but insect pharmacies as well. Trees and other plants have beneficial chemicals essential to the health of bugs. Some monarchs, when afflicted with parasites, seek out more toxic types of milkweed because they kill the parasites. Bees use medicinal resins from aspen and willow trees that are antifungal, antimicrobial and antiviral, to line their nests and to fight infection and diseases. “Bees scrape off the resins from the leaves, which is kind of awesome, stick them on their back legs and take them home,” said Dr. Spivak.

Besides pesticides and lack of habitat, the other big problem bees face is disease. But these problems are not separate. “Say you have a bee with viruses,” and they are run-down, Dr. Spivak said. “And they are in a food desert and have to fly a long distance, and when you find food it has complicated neurotoxins and the immune system just goes ‘uh-uh.’ Or they become disoriented and can’t find their way home. It’s too many stressors all at once.”

There are numerous organizations and individuals dedicated to rebuilding native plant communities one sterile lawn and farm field at a time. Dr. Tallamy, a longtime evangelizer for native plants, and the author of one of the movement’s manuals, “Bringing Nature Home,” says it’s a cause everyone with a garden or yard can serve. And he says support for it needs to develop quickly to slow down the worsening crisis in biodiversity.

When the Florida Department of Transportation last year mowed down roadside wildflowers where monarch butterflies fed on their epic migratory journey, “there was a huge outcry,” said Eleanor Dietrich, a wildflower activist in Florida. So much so, transportation officials created a new policy that left critical insect habitat un-mowed.

That means reversing the hegemony of chemically green lawns. “If you’ve got just lawn grass, you’ve got nothing,” said Mace Vaughan of the Xerces Society, a leading organization in insect conservation. “But as soon as you create a front yard wildflower meadow you go from an occasional honeybee to a lawn that might be full of 20 or 30 species of bees and butterflies and monarchs.”

First and foremost, said Dr. Tallamy, a home for bugs is a matter of food security. “If the bees were to truly disappear, we would lose 80 percent of the plants,” he said. “That is not an option. That’s a huge problem for mankind.”

Jim Robbins is a frequent contributor to The New York Times and the author of “The Man Who Planted Trees.”

Kitchen Botany Lesson #1: The Sex Lives of Plants

For some of you just hearing the word “botany” brings forth images of dreary classroom sessions and nerdy be-spectacled professors with wild unkempt hair. My experience of botany has been quite the opposite (well, except for maybe the unkempt hair). Botany is all about the sex lives of plants. Flowers, the sex organs of plants, are quintessentially beautiful and incredibly diverse. Pollination is an intricate a dance of plant insect wind and chance. If you have never taken a field study course, it is highly recommended. Heading down a mountain path in search of some obscure beauty, you never know what wonders nature will show you along the way. Botany classes for non-academics are available at the Jepson Herbarium, Sierra Nevada Field Campus and Tilden Botanic Garden (besides their public classes they also offer a 20 week docent training)

In the garden some knowledge of plant taxonomy is necessary of you want to take your sustainability and skills to the next level. Plants in the same family act similarly in how they reproduce and plants of the same species may or may not cross to produce something that resembles the parent. This is important if you want in on the tradition of saving and growing out your own seed. Seed is living gold; the genetic material of the flavours we love. Saving heirloom seed properly is the next step in true sustainability and independance from giants like Monsanto.

How Pollination Happens

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The female part of the flower is called the pistil which includes the stigma, style and ovary. The stigma has a sticky surface which will chemically “recognizes” only pollen of the same species. The ovary, is what will become the fruit and within it the seeds. The male part of the flower is the stamen which includes the filament and anther. The anthers produce the pollen. Some plants have male and female parts in the same flower and are self-pollinating within the same flower. Tomatoes are an example of this. Some have male and female parts in the same flower, but have evolved mechanisms to prevent self-pollination and ensure genetic diversity. Some plants have separate male and female flowers on the same plant, such as zucchini and other squash. Finally, some plants have male and female flowers on separate plants, thus requiring two plants to reproduce. Avocado trees are an example of this.

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So finally getting to the amazing part, here. The pollen grain is made up of 2 cells. When a pollen grain of the right type lands on the sticky stigma, the hard outer coat of the pollen grain starts to dissolve. The first cell, called the “tube cell” grows like a tube down the style to the ovary where the second cell fertilizes the ovule to make a seed. The tube cell can grow as much as 12 inches to reach it’s goal! In corn, for example, each silk is one style leading to one ovule which will become one kernel of corn. When the pollen from the tassels lands on the silks, the pollen tube grows all the way down the silk to fertilize the one ovule. Wow. This story will continue next month with a bit about plant families and beginning seed saving!

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K. Ruby Blume, Institute for Urban Homesteading