HERE ARE A PARTICULARLY INTERESTING ITEMS picked from the latest installment of the Wild Ones organization's e-mail newsletter:
Wild Ones now has its own channel on YouTube. At the moment they have 7 videos including tours of the new Wild Ones Ecocenter now and 11 months ago. The rest are photo contests from 2003 through 2008.
The website of the US Fish and Wildlife Service National Wildlife Refuge System now has an educational offering titled Managing Invasive Plants: Concepts, Principles, and Practices. This is designed for people who are managing large natural areas on public land in the United States but some ideas could be adapted to gardens and smaller landscapes. From the gardener's standpoint, the most useful information is in the section on management, particularly physical, chemical, and biological methods of control. If you have enough land, you may be interested in the sections on prescribed grazing (I'm planning to take a good look at the section on goats) and prescribed burning. All the sections are overviews, so if you already know a lot about control of invasive species you may find that there is not much new here.
The Pollinator Partnership is offering a number of handouts that were prepared for the 2008 Pollinator Week last June. These are in pdf format and include:
Showing posts with label invasive plants. Show all posts
Showing posts with label invasive plants. Show all posts
Vanishing Birds
Photos: Top, populations of the rufous hummingbird have declined 58% since 1967, according to a new study just released by the Audubon Society. Left, populations of evening grosbeaks have declined 78%. Both photos courtesy the U.S. Fish and Wildlife Service, via the Wikipedia.THE AUDUBON SOCIETY HAS JUST RELEASED an analysis of 40 years of reports on bird populations with the unhappy conclusion that many bird species are in decline: "Since 1967 the average population of the common birds in steepest decline has fallen by 68 percent; some individual species nose-dived as much as 80 percent. All 20 birds on the national Common Birds in Decline list lost at least half their populations in just four decades."
A surprising number of these species would be familiar to most gardeners. Among the popular "backyard birds" that made the list was one of my own favorites, the evening grosbeak. Populations of this large black and yellow bird, which has a distinctive bright yellow slash above its eye, are down an astonishing 78% since 1967. (The decline in this species is second only to the decline in populations of the northern bobwhite, down 82%.) If you live almost anywhere in the United States or southern Canada, you've probably hosted flocks of these birds at your feeders.
Another surprise is the decline in populations of the common grackle, a member of the Corvid (crow) family, that is often seen in urban areas and parks. Because it seems to get along well with humans, I wouldn't have expected this bird to be in decline--but it is, down 61%.
Populations of rufous hummingbirds, which are the hummingbirds most likely to be seen at feeders on the West Coast, are down 58%.
If you live in a rural area or area where there is still natural habitat left, you are likely to spot a lot more good friends on this list: The boreal chickadee (down 73%), eastern meadowlark (72%), field sparrow (68%), and ruffed grouse (54%) are just a few examples from the "top 20" list.
All of these declines can be attributed, one way or another, to loss of habitat. Farmland and meadow birds are suffering because of suburban sprawl, industrial development, and the replacement of old-fashioned farming methods with intensive agriculture. Other birds are in trouble because of climate change, deforestation, and loss of wetlands.
None of these species is on the verge of extinction, at least not yet. But such huge declines are very worrisome. What can we, as wildlife-friendly gardeners, do? Here are Audubon's recommendations, with my comments:
- Protect local habitat. This would include gardening and landscaping in a wildlife-friendly way, as well protecting natural areas where they still exist in your neighborhood. You can also support organizations, such as the Nature Conservancy, that protect critical habitat areas.
- Support sustainable forests. One good way to do this is to buy wood products certified by the Forest Stewardship Council, which is the toughest of the certification programs. The Audubon Society notes that this would be especially helpful to our friends the evening grosbeaks, as they are dependent on boreal forests as breeding grounds.
- Promote sound agricultural policy. Agriculture has a tremendous impact on wildlife, and our shopping and eating choices have a tremendous impact on agriculture. Once you've made your own property wildlife friendly, it seems to me that the natural "next step" is to support farmers who manage their land in a wildlife-friendly way. You can do this by shopping for organic, locally grown, seasonal foods and getting to know your local food producers. Let them know that you care about wildlife-friendly farming practices.
- Protect wetlands. If you have wet areas on your own land, large or small, value them, plant them with native plants, and protect them. They are essential not only for many birds but also for other animals, particularly amphibians.
- Fight global warming. There are lots of ways to do this, but as gardeners we can avoid using tools that are powered by gasoline or electricity, plant trees, landscape in such a way that we reduce heating and cooling costs in the home, improve soil quality, grow our own vegetables ... and probably quite a few other things as well.
- Combat invasive species. This recommendation is particularly relevant to gardeners, as sadly we have been responsible for the introduction of far too many species that have caused degradation of wildlife habitat. The easiest way to avoid planting invasive species and help wildlife at the same time is to garden with native plants.
All Plants Are Not Native Everywhere
EVERY NOW AND THEN, I hear someone say, "Every plant is native somewhere." Of course, this is true in the literal sense. But as far as I can figure out, what people usually mean by this statement is something along the lines of, "All plants are native, so it's ok for me to plant anything I want." That's not so true, and I'd like to explain why.
First let's talk about how the word native is defined by people like me, who say that we "garden with native plants." Typically those of us who live in North America use this word as shorthand for "plants that were present in a specific place before the arrival of European settlers."
Why do we place the dividing line at the arrival of Europeans? Because Europeans brought a lot of plants with them when they came. So in a very short period of time, the ecosystems that had existed in North America for thousands of years, evolving very slowly, were suddenly invaded by plants that had never been seen on this continent before. Now, that wasn't always bad. I happen to be rather fond of dandelions (one of the "newcomers") myself. But often the new plants have spread to and invaded the original ecosystems, crowding out the plants that have been here for thousands of years. When those plants are gone, the animals that depend on them for food and shelter often become threatened too.
As a matter of fact, I got interested in native plant gardening primarily because I like birds and other wildlife. I started out as a wildlife-friendly gardener, just trying to plant things that animals would like, without paying any attention to whether the plants were native or not. But the more I learned about wildlife and plants, the more I came to realize how much wild birds and other animals depend on the plants that have been in their environment for a very long time. I began to realize that newer introductions just can't replace the plants that animals have evolved with. That's when I started adding native plants to my garden.
Here's one of my favorite examples of why it's so important to make a distinction between plants that are native "somewhere" and plants that are native in our local area: In 1999, researchers from Illinois and Tennessee reported on the results of a study of an Illinois forest preserve that had been overrun by non-native honeysuckle and buckthorn. Honeysuckle had replaced the arrowwood that was native there, and buckthorn had replaced the native hawthorn. Both the honeysuckle and the buckthorn were probably introduced (at least in part) by gardeners. Birds visit gardens, eat the berries from these plants, fly into the forests, and then "deposit" the plants; the plants grow extremely well in forested areas, typically displacing the native plants.
Buckthorn, for example, tends "to form dense, even-aged thickets, crowding and shading out native shrubs and herbs, often completely obliterating them." (Plant Conservation Alliance Alien Plant Working Group).
Japanese honeysuckle "has few natural enemies which allows it to spread widely and out-compete native plant species. Its evergreen to semi-evergreen nature gives it an added advantage over native species in many areas. Shrubs and young trees can be killed by girdling when vines twist tightly around stems and trunks, cutting off the flow of water through the plant. Dense growths of honeysuckle covering vegetation can gradually kill plants by blocking sunlight from reaching their leaves. Vigorous root competition also helps Japanese honeysuckle spread and displace neighboring native vegetation." (PCA Alien Plant Working Group)
But you could say, So what? If the birds like the berries, why does it matter whether the forest is composed of non-native plants or native plants? Aren't they all plants?
Well, that brings us to the research that was conducted in Illinois. What the researchers found was that nest predation of American robins and wood thrushes was higher in the non-native shrubs than in the native shrubs and trees. According to the press release that was issued at the time, they thought this was "partly due to physical differences between the native and non-native shrubs. Buckthorn lacks hawthorn's sharp thorns, which could deter mammalian predators. Honeysuckle has sturdier branches, which could both help predators climb higher and support nests closer to theground, where they are more accessible to predators."
So in other words, even though these plants appeal to birds, who like to eat the berries, in the long term the plants are hurting birds that are already at serious risk: "In recent years, the Wood Thrush, like many other Neotropical migrants, has undergone an alarming population decline." (Cornell Laboratory of Ornithology)
This is just one example, but I think it highlights the risks that are associated with introducing non-native invasive plants: These plants can and all too often do replace native plants when they compete with them in natural areas. When the native plants are replaced by non-native plants, the effects on wildlife are unpredictable but often damaging.
And that's why it's so important to try to protect the plants that are native right here, not "somewhere."
Fortunately, all non-native plants are not equally dangerous. There are plenty of non-natives that are not invasive and are beneficial for wildlife, which is why I do discuss non-natives and I also use them in my garden. Ideally each non-native plant would be given a fair hearing, and we would draw conclusions on a case-by-case basis. Unfortunately, there isn't always time to study every plant before someone introduces it. And we already have far too many examples of invasive non-native plants that have been introduced by gardeners. Also, many of the plants that are native to specific regions are being lost at an alarming rate, along with the native wildlife they support. That's why I think it's so important for gardeners to make an effort to use more natives in their gardens, and why I encourage gardeners to be very cautious about introducing new non-native plants.
First let's talk about how the word native is defined by people like me, who say that we "garden with native plants." Typically those of us who live in North America use this word as shorthand for "plants that were present in a specific place before the arrival of European settlers."
Why do we place the dividing line at the arrival of Europeans? Because Europeans brought a lot of plants with them when they came. So in a very short period of time, the ecosystems that had existed in North America for thousands of years, evolving very slowly, were suddenly invaded by plants that had never been seen on this continent before. Now, that wasn't always bad. I happen to be rather fond of dandelions (one of the "newcomers") myself. But often the new plants have spread to and invaded the original ecosystems, crowding out the plants that have been here for thousands of years. When those plants are gone, the animals that depend on them for food and shelter often become threatened too.
As a matter of fact, I got interested in native plant gardening primarily because I like birds and other wildlife. I started out as a wildlife-friendly gardener, just trying to plant things that animals would like, without paying any attention to whether the plants were native or not. But the more I learned about wildlife and plants, the more I came to realize how much wild birds and other animals depend on the plants that have been in their environment for a very long time. I began to realize that newer introductions just can't replace the plants that animals have evolved with. That's when I started adding native plants to my garden.
Here's one of my favorite examples of why it's so important to make a distinction between plants that are native "somewhere" and plants that are native in our local area: In 1999, researchers from Illinois and Tennessee reported on the results of a study of an Illinois forest preserve that had been overrun by non-native honeysuckle and buckthorn. Honeysuckle had replaced the arrowwood that was native there, and buckthorn had replaced the native hawthorn. Both the honeysuckle and the buckthorn were probably introduced (at least in part) by gardeners. Birds visit gardens, eat the berries from these plants, fly into the forests, and then "deposit" the plants; the plants grow extremely well in forested areas, typically displacing the native plants.
Buckthorn, for example, tends "to form dense, even-aged thickets, crowding and shading out native shrubs and herbs, often completely obliterating them." (Plant Conservation Alliance Alien Plant Working Group).
Japanese honeysuckle "has few natural enemies which allows it to spread widely and out-compete native plant species. Its evergreen to semi-evergreen nature gives it an added advantage over native species in many areas. Shrubs and young trees can be killed by girdling when vines twist tightly around stems and trunks, cutting off the flow of water through the plant. Dense growths of honeysuckle covering vegetation can gradually kill plants by blocking sunlight from reaching their leaves. Vigorous root competition also helps Japanese honeysuckle spread and displace neighboring native vegetation." (PCA Alien Plant Working Group)
But you could say, So what? If the birds like the berries, why does it matter whether the forest is composed of non-native plants or native plants? Aren't they all plants?
Well, that brings us to the research that was conducted in Illinois. What the researchers found was that nest predation of American robins and wood thrushes was higher in the non-native shrubs than in the native shrubs and trees. According to the press release that was issued at the time, they thought this was "partly due to physical differences between the native and non-native shrubs. Buckthorn lacks hawthorn's sharp thorns, which could deter mammalian predators. Honeysuckle has sturdier branches, which could both help predators climb higher and support nests closer to theground, where they are more accessible to predators."
So in other words, even though these plants appeal to birds, who like to eat the berries, in the long term the plants are hurting birds that are already at serious risk: "In recent years, the Wood Thrush, like many other Neotropical migrants, has undergone an alarming population decline." (Cornell Laboratory of Ornithology)
This is just one example, but I think it highlights the risks that are associated with introducing non-native invasive plants: These plants can and all too often do replace native plants when they compete with them in natural areas. When the native plants are replaced by non-native plants, the effects on wildlife are unpredictable but often damaging.
And that's why it's so important to try to protect the plants that are native right here, not "somewhere."
Fortunately, all non-native plants are not equally dangerous. There are plenty of non-natives that are not invasive and are beneficial for wildlife, which is why I do discuss non-natives and I also use them in my garden. Ideally each non-native plant would be given a fair hearing, and we would draw conclusions on a case-by-case basis. Unfortunately, there isn't always time to study every plant before someone introduces it. And we already have far too many examples of invasive non-native plants that have been introduced by gardeners. Also, many of the plants that are native to specific regions are being lost at an alarming rate, along with the native wildlife they support. That's why I think it's so important for gardeners to make an effort to use more natives in their gardens, and why I encourage gardeners to be very cautious about introducing new non-native plants.
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