Welcome to the Grow Native, Don’t Plant a Pest Campaign! This is a public outreach project of the Arizona Native Plant Society, designed to educate citizens about how their landscaping choices can affect Arizona’s wild places and natural areas.
(read slide). There are about 600 members statewide, with chapters in Tucson, Phoenix, Flagstaff, Yuma, and Prescott.
Sometimes all of the different words used to describe unwanted plants can be confusing and have overlapping meanings: *weeds *invasives *non-natives *alien *exotic The plants that we are talking about in this campaign are INVASIVE and NON-NATIVE. A good definition of this terminology comes from the US Department of Agriculture National Invasive Species Information Center: “a non-native (or alien) species to the ecosystem under consideration, whose introduction is likely to cause economic or environmental harm to human health. So, we are talking about plants that do not naturally occur in a particular area, and that have harmful effects.
As the Arizona Native Plant Society, our campaign focuses on plants. However, it is important to understand that the term “invasive” can be used to describe other life forms, as well. Examples include animals such as: zebra mussels, bullfrogs, brown tree snakes, European starlings, cactus moths and red imported fire ants, as well as microbes such as West Nile virus. One could even argue that humans have become invasive!
You have probably encountered invasive plant species from living or traveling in other places. Let’s look at a couple of conspicuous examples from across the United States that you may recognize.
Kudzu is a voracious woody vine that can grow as fast as one foot per day under ideal circumstances -- and it has overrun over 7 million acres of the southeastern United States. It was introduced in 1876 from Japan for its value as an ornamental and also for its usefulness in erosion control. Southerners joke that you have to keep your windows closed at night to keep kudzu out!
Purple loosestrife also came to the northeastern US in the 1800s for use as an ornamental. According to the US Fish and Wildlife Service, this plant is now found in every state except Florida, although its worst infestations are in the wetlands of northeastern and northwestern states.
How about the non-native invasive species of the Sonoran Desert – how did they make their way to the Sonoran Desert? Some of the answers are surprising!
Many of our non-native invasives arrived by accident. Sahara mustard, for instance, arrived in California’s Coachella Valley as a contaminant in date palm seeds from the Middle East in the 1930s. This annual plant is a prolific seed producer that blooms earlier than native desert annuals. It is also called “tumble mustard,” because once it dries out the stems break and it can roll and blow far and wide, dispersing its seeds along the way. This species has marched all the way from the Coachella Valley to Tucson in recent decades, and has dramatic impacts on wildflower displays, as seen in these photos from southwestern Arizona.
Other species were purposefully introduced to the southwest with beneficial intentions. At the right is tamarisk, or as it is sometimes called, salt cedar. This Eurasian species was brought here in the 1850’s as an ornamental and for erosion control. It quickly spread into natural wetlands, where it forms dense thickets along streams and springs, displacing native riparian trees such as cottonwood, willow and mesquite. Tamarisk has spread so extensively throughout the southwest that almost every watercourse is infested – more than one million acres, according to the National Park Service ( http://www.nps.gov/archive/whsa/tamarisk.htm ). At the top left of this slide is Lehmann’s lovegrass, which was introduced by the Soil Conservation Service in the 1930’s for cattle forage. This grass from Africa now carpets much of southeastern Arizona and has dramatically diminished the diversity of native grassland species. Below that is another species brought from Africa to Arizona by the Soil Conservation Service for cattle forage and erosion control – buffelgrass. You may have already heard about this one, but if not, we’ll talk about the disastrous ecological and economic impacts of this species in the next couple of slides.
This photo is from the Cave Creek Complex Fire that burned outside of Phoenix in the summer of 2005. This fire was fueled by invasive non-native grass, and it demonstrates one of the most frightening impacts of certain invasives – that they bring fire to the desert, which can result in loss of life and property.
The Sonoran Desert is not adapted to carry wildfire. When you look out on a natural Sonoran Desert landscape, you may notice that the plants are generally widely spaced. This ensures that when a natural fire is ignited by lightening , that it really can’t go very far because there is not enough fuel to carry it. Fires are extremely localized and cause minimal damage, which is a good thing, because our desert plants are not adapted to withstand fire. Fire kills most cactus (including saguaros) and desert trees. When buffelgrass invades a site, it forms dense stands that fill in the natural spaces between the native plants, allowing for a fire to carry over a much larger area. This problem is compounded by the fact that human-caused fires are on the increase – cigarettes, campfires, vehicles. More types of ignition plus more invasive species fuels equals trouble for our desert areas!
For more information about buffelgrass, check out these websites!
But what can the average citizen do about the invasive species problem in their own front yards? The remainder of this presentation focuses on invasive species that are here because we like to use them as ornamentals. These species present us with a special opportunity to affect the larger invasive species issue because we can: Remove them from our residential landscapes and gardens. Choose native species instead. Tell our neighbors and friends about them.
To illustrate the documented effects that ornamental invasives can have on natural areas, let’s look at some research from the Desert Laboratory on Tumamoc Hill in Tucson, AZ. This facility was established on the western outskirts of Tucson by scientists with the Carnegie Institute in 1903 for the purpose of studying desert plants. In this slide, you can see the extensive long-term ecological studies that have occurred here; as Tumamoc Hill is now almost completely enveloped by urban developments, it also is an ideal site to investigate the spread of ornamental invasives. http://wwwpaztcn.wr.usgs.gov/dlab_about.html
And so researchers at the Desert Laboratory decided to take a look and whether there had been any changes in ornamental invasives between 1983 and 2005.
This aerial photo demonstrates what researchers found in regard to one invasive species – African sumac. Notice the dark green linear washes traverse Tumamoc Hill and into adjacent neighborhoods. The lime green dots represent locations for African sumac trees that are literally marching their way out of the neighborhood and invading the natural watercourses.
The take home messages from the study were that the proportion of invasive species at Tumamoc Hill that were ornamental -- that is, that originated from the plantings in the adjacent neighborhoods – doubled in 22 years! And, the longer a species had been present in cultivation, the more likely it was to be invasive. Let’s look at this a little closer. In 1983, there were 34 invasive species, and 9 of them (26%) were ornamental species. In 2005, there were 10 additional invasive species for a total of 44, and nearly half of them were ornamental! This showed that as time progresses, natural areas that are adjacent to urban horticulture and landscaping are increasingly vulnerable to ornamental invasive species.
The goals of the Grow Native: Don’t Plant a Pest brochure are to identify ornamental plant species that are invasive in southeastern Arizona wildlands and to suggest native species that offer similar characteristics without the threat of invasiveness.
In developing the Grow Native brochure, the Arizona Native Plant Society used up to date scientific information to choose the featured non-native invasive species. The parameters that were used included: Known impacts to wildlands Transparent scientific assessments Use in southeastern Arizona landscapes
alterNATIVE species were chosen by a committee of ecologists, landscape professionals, and botanists. The goal was to choose species that are: Native to southeastern Arizona Currently available in the nursery trade Similar to the pest species in appearance, function, and/or life history.
Now onto the plants! This is a photo of Sabino Canyon, a favorite recreation area in the Catalina Mountains of Tucson. Walking through Sabino Canyon, many visitors may assume that all the plants they see are a part of the natural landscape. However, a trained eye reveals many non-native invasives, many of which are ornamental. Many of these species are featured in our Grow Native: Don’t Plant a Pest brochure, and we have used the same color cues here – a red border around a plant means that it is a trouble-maker, whereas a green border indicates a desirable native alterNATIVE.
FOUNTAIN GRASS. Remember buffelgrass? Well, here is it’s cousin, also from Africa, fountain grass, which you will see in many residential landscapes across southern Arizona. Fountain grass tends to stick to washes and canyons, and the Forest Service is trying desperately to remove it from Sabino Canyon. It grows in dense clumps, crowds out native species and creates a fire hazard.
Here is an urban wash and hillside choked with fountain grass (as well as Bermuda grass, which we will discuss later). How did it get here from Africa? Probably via Home Depot, where an unsuspecting neighbor thought it would look very nice in their front yard. Each fountain grass plant produces thousands of seeds that are dispersed widely by wind and water.
http://www.calipc.org/ip/management/ipcw/pages/detailreport.cfm@usernumber=66&surveynumber=182.php In short, NO. Even though it is considered to be “sterile,” that does not mean that it is not capable of producing any seed. In one study the purple cultivar set as high as 18 percent seed following application of buffelgrass pollen! (see CALIPC website)
The good news is that we have several striking native species to use instead of fountain grass in our landscapes and gardens! If you have space, desert spoon makes a statement more dramatic than fountain grass could dream of! This is a long-lived perennial that remains interesting to look at all year long. Arizona cottontop is a native grass that has beautiful white seed heads that come to life in the summer with the monsoon rains. This species will spread, so if you might choose something different if you need a plant to “stay in its place”.
Another lovely ALTERNATIVE to fountain grass is desert milkweed. It has a very similar form, with clusters of white flowers at the tips of the stems. This plant has the added benefit of attracting butterflies to your garden!
Here is another trouble-maker that you can see as you walk through Sabino Canyon – giant reed. The photo on the right is from a residential landscape – it has been a popular plant to use for privacy and windbreaks, however it also escapes into washes and rivercourses.
A great ALTERNATIVE for privacy or windbreak can be found in Arizona rosewood. This is an evergreen species that has clusters of white flowers. It can be trained as a tree, shrub, or even a tall hedge, and is also a great ALTERNATIVE to oleander!
African sumac is the species that we saw marching up the washes to Tumamoc Hill. It is easy to see why this tree became popular – it has a graceful, spreading form that is attractive and produces shade.
One of the reasons it has been a popular tree is that it grows quickly. But is also produces requires constant maintenance because of all of the seedlings and suckers that it produces.
The most obvious ALTERNATIVE is velvet mesquite, a large native tree with a graceful form and ample shade. Beware the non-native mesquites that are widely available (usually labeled “South American or Chilean”) – look for Prosopis velutina . If it is the evergreen color you are after, a nice ALTERNATIVE choice is sugar sumac ( Rhus ovata ). This species stays shrubby and may require a location that is not in full sun.
Vinca or periwinkle is an attractive vining plant that offers striking purple-blue flowers….
But, it also overruns riparian areas when it gets loose. It took a troop of Boy Scouts countless hours to remove it from this streamside in Ramsey Canyon.
Gooding verbena is a great ALTERNATIVE – it can fill in areas with purple blooms that are very popular with butterflies. Desert four o’clock is also a nice choice, although not as commonly found in the local nursery trade.
Desert snow is also a great ALTERNATIVE if you’d like a plant that can climb up a fence; it has delicate white flowers.
Bermuda grass is everywhere, and very difficult to remove. It reproduces with underground runners as well as by seed, and it persists wherever there is a little extra water.
There are lots of alterNATIVES to a Bermuda grass lawn, including pea gravel, the use of native grasses, cactus gardens, artificial turf, and wildflower carpets, depending on how you need to use the space. These ALTERNATIVES can be beautiful and water-conservation friendly!
Here are a few more species that we did not have room for in the brochure….
African daisies. These annual wildflowers are coveted for the brilliant orange carpets they produce in landscapes. They are very easy to cultivate…..and they have escaped into wild places.
Why use African daisies when the glorious native Mexican gold poppies can also carpet your front yard?
The yellow bird of paradise is a prolific seeder that has been found naturalizing extensively beyond the yards and gardens it was originally planted in. (there is not yet evidence to suggest that the red bird of paradise is invasive)
A wonderful ALTERNATIVE is baby bonnets. This thornless legume shrub produces pea flowers that are white, yellow, and pink. It is sensitive to cold and should be placed in an area where it can be protected from freezing.
Hopbush is readily available in local nurseries and it has many desirable qualities: Evergreen Grows fast papery fruits that add interest and color Can also be used for privacy screening
Feathery cassia, from Australia, has become a favorite shrub in the newer developments in southern Arizona, but it is a prolific seeder and is beginning to escape into natural areas.
Shrubby senna is a native shrub that produces brilliant yellow flowers.
Jojoba is a hearty Sonoran Desert shrub that can be used as an attractive alterNATIVE to feathery cassia – it has a very dense growth form that can be used for screening and the female plants produce edible nuts.
Shoestring acacia is also from Australia, and has become popular especially in the smaller yards of newer housing developments because it grows quickly and has a narrow canopy. However, nursery personnel have reported that it produces lots of seedlings, which is a bad sign.
A wonderful alterNATIVE for tight spots is another acacia species that is native to the Sonoran Desert. It is palo blanco, and you can see its striking white peeling bark in this picture. It grows naturally in the canyons of Sonora, Mexico, just south of Arizona, and so it is sensitive to freezing temperatures and should be planted in a location that gives it protection from the cold.
Have you noticed a pattern here? Plant species that tend to become a problem here in the Sonoran Desert usually originate from areas of the world that have similar climate (the orange “dry” areas in the world map above). Because these species are adapted to conditions similar to the Sonoran Desert, they are physiologically well-prepared to thrive here. What’s more, they are often successful in “leaving the garden,” because they do not have their native pests and diseases to keep them in check. So if you see “African, Australian, Mediterranean, or South American” in a plant’s name or description, chances are it could be a problem for the natural areas of the Sonoran Desert.
What are actions that YOU can take to protect Arizona’s natural habitats and native plants from the impacts of non-native invasive ornamental species?
Well, the first thing is easy – use native plants in your landscapes and gardens. For a list of nurseries that sell native plants in your area, check out the Arizona Native Plant Society website at http://www.aznps.org/sources.html
Backyard ponds are becoming a very popular landscape amenity. Be careful to include only native plants and animals in your backyard pond.
If you have any of the invasive plant species featured in this presentation growing in your yard, you want to remove them so that they do not spread farther. This can be a big job, and it pays to have the right tools and techniques. Please contact the Arizona Native Plant Society if you need more information about the best way to handle a particular species.
Talk to your neighbors about ornamental invasives. Contact the Arizona Native Plant Society if you’d like some Grow Native: Don’t Plant a Pest brochures to pass out!
If you are not finding the native species you want at your favorite nurseries, talk to the manager and let them know. As public demand for safe native species increases, so will the supply.
And of course, if you are interested in learning more, please join the Arizona Native Plant Society!
Grow Native! Don’t Plant a Pest A public outreach campaign from the Arizona Native Plant Society
The Arizona Native Plant Society is a statewide nonprofit organization devoted to Arizona's native plants. Its mission is to promote knowledge, appreciation, conservation, and restoration of Arizona native plants and their habitats.
<ul><li>1. Are not from other ecosystems. </li></ul><ul><li>2. Cause economic or environmental harm as they spread! </li></ul>INVASIVE, NON-NATIVE SPECIES
Animals and Microbes can be Invasive Non-Native Species, too! Cecil Schwalbe Kansas Department of Wildlife and Parks www.answers.com www.mdinvasivespecies.com www.wikimedia.com
Carianne Funicelli Non-Native Invasive Plants… How did they get to the Sonoran Desert?
1998 2005 By Accident… Sahara mustard (Brassica tournefortii) Images from this slide graciously stolen from Mark Dimmit, Arizona-Sonora Desert Museum
On Purpose … Michael Chamberland Travis Bean Lehmann’s lovegrass (Eragrostis lehmanniana) Tamarisk or Salt Cedar (Tamarix spp.) Buffelgrass (Pennisetum ciliare)
Cave Creek Complex Fire, July 2005 243,310 acres burned IMPACTS of INVASIVES <ul><li>FIRE </li></ul><ul><li>Crowding out of native vegetation </li></ul><ul><li>Sense of place, economic values </li></ul>
Saguaros & other desert plants and animals are not fire-adapted Slide from Saguaro National Park
<ul><li>http://www.buffelgrass.org </li></ul><ul><li>http://ai.desertmuseum.org/invaders </li></ul><ul><li>http://wwwpaztcn.wr.usgs.gov/buffelgrass </li></ul>For more information about buffelgrass:
Ornamental introductions can be a source of invasives… Residential landscaping decisions can be on the frontline of defense
B 15 16 14 12 11 A 10 7 9 4 Winter Annuals Experimental Plots sewer line Saguaro plot Saguaro plot Saguaro plot Saguaro plot Winter annuals Blue paloverde Riparian study Buffelgrass/ paloverde Historic permanent plots Creosote/ soil study Plant community/scaling study Common School Trust Land-320 acres The Desert Laboratory on Tumamoc Hill
Two decades of change in distribution, frequency, and richness of exotic plants J. E. Bowers 1 , T. M. Bean 2 , and R. M. Turner 1 The Desert Laboratory on Tumamoc Hill 1 U. S. Geological Survey, Water Resources Division 2 University of Arizona, School of Natural Resources
African sumac invading from adjacent neighborhoods Silvercroft Wash
TAKE HOME MESSAGES <ul><li>Proportion of ornamental exotics doubled in 22 years as they spread from the nearby housing developments. </li></ul><ul><li>Longer a species is present, the more likely it will become invasive </li></ul><ul><li>Natural areas are becoming increasingly vulnerable to urban landscaping </li></ul>
Grow Native! Don’t Plant a Pest <ul><li>Identify ornamental plant species that are invasive in southeastern Arizona wildlands </li></ul><ul><li>Present native alternative species (alterNATIVES) </li></ul>
Featured invasive ornamentals were chosen based on: <ul><li>known impacts to wildlands </li></ul><ul><li>transparent scientific assessments </li></ul><ul><li>use in southeastern Arizona landscapes </li></ul>
Featured AlterNATIVES were chosen based on: <ul><li>Current availability in the nursery trade </li></ul><ul><li>Similar in: </li></ul><ul><ul><li>Appearance </li></ul></ul><ul><ul><li>Function </li></ul></ul><ul><ul><li>Life history </li></ul></ul>