RESTORING NATURE ONE GARDEN AT A TIME       (A pdf of this article is available for download here.)

by Donna Wildearth

Published in the Winter 2019 issue of Darlingtonia

Insects are making headlines—again. For years we have heard troubling reports of the crisis in honeybee populations, and there have been articles about the alarming decline of monarch butterflies (as much as 96% since 1976 in central and eastern U.S). But recent news stories are revealing a more widespread problem.

In September 2018 the Associated Press released an article entitled “Bye bye bugs? Scientists fear non-pest insects are declining” (Times-Standard, September 23, 2018). The study noted that scientists in the U.S., Canada, Costa Rica, Germany, Denmark, and Greenland who study beneficial flying insects such as bees, moths, butterflies, ladybugs, and fireflies are reporting declining populations. One study estimated a 14 percent decline in ladybugs in the United States and Canada from 1987 to 2006, while a 2017 study of 63 nature preserves in Germany found an 82 percent mid-summer decline in the number and weight of bugs compared to 27 years earlier.

On October 15 the Washington Post ran an article entitled “’Hyperalarming’ study shows massive insect loss,” detailing the results of a study in Puerto Rico where a sharp drop in the number of moths, butterflies, grasshoppers, and spiders was accompanied by steep declines in the number of insect-eating lizards, frogs, and birds. In Tallamy’s lecture he referred to a study that estimates invertebrate abundance worldwide has declined by 45% since 1974.

Should we care about this news? The answer is a resounding yes, because insects are the basis of the food web on land.And if insects are declining, multiple other organisms that eat insects are also at risk. Insects are highly nutritious, rich in protein and fat, and are an important component of the diet even for such animals as the red fox (25% of their diet) and black bear (23% of their diet)! Tallamy’s lecture focused on an issue that many people aren’t aware of: the crucial importance of insects for birds. Ninety-six percent of terrestrial birds in this country raise their young on insects, primarily caterpillars. So if insect populations are declining, it isn’t surprising to learn that roughly one-third of the birds in this country are at risk of extinction. The 2016 State of the Birds report found 15 billion fewer birds breeding in the U.S. compared to 40 years ago. Caterpillars are an essential food for baby birds. Caterpillars are large and soft compared to other insects, making them easy for nestlings to digest. Caterpillars are also higher in carotenoids than many other insects, and these carotenoids provide immune system support, antioxidants, and the nutrients that birds need to develop the bright colors of their feathers.  A 1961 study found that Carolina chickadees require between 6,000 and 9,000 caterpillars to successfully raise one brood of young birds.

If insects are vital components of the food web, the next question is what plants produce the most insects, especially caterpillars? This seems to fly in the face of conventional gardening wisdom which regards most insects as pests. But the bottom line of current research is that if we want to encourage birds in our gardens we need to grow plants that will serve as hosts to a variety of insects.And the plants that do this best are native plants.

Native plants harbor more insects because 90% of leaf-eating insects are specialists in terms of which plants they can eat. Plants don’t want to be eaten, so in order to overcome the chemical and physical defenses that plants have developed, these specialist insects need to have co-evolved with a particular lineage of plants for thousands of years. A good example of this is the monarch butterfly, which has a long evolutionary history with milkweeds that has enabled the butterfly to work out how to eat the plant without being poisoned by its toxic chemicals. Tallamy and his students counted the numbers of caterpillars on a native oak tree and found 410 caterpillars from 19 species. In comparison, on a non-native Bradford pear, a popular ornamental,they found ­­­­­exactly one.In a recent study in a Washington, D.C. suburb one of Tallamy’s students found that, compared to native plant landscapes, yards dominated by non-native plants produced 75% fewer caterpillars. This study concluded that only yards with more than 70% native plant biomass can sustain chickadee populations. Non-native plants are not evil in themselves—though some are certainly problematic in terms of invasiveness. They are simply plants that have not been here long enough to evolve a relationship with insect herbivores. And this is true even though some, like the ginkgo, have been grown on U.S. soil for 400 years.

Tallamy and his students have further discovered that 5% of native species of plants produce 75% of the caterpillars they studied. They call these the native super plants. On the east coast these are native oaks, plums and cherries,willows, and pine. White oak(a different species than our local white oak), for instance,supports 557 species of caterpillars, produces acorns that help support food webs, and serves as habitat and nesting sites for many birds and mammals.

Tallamy’s group has developed a list of the most productive native plants, searchable by zip code, for every area of the country except California—because our state is so large and diverse. What are our native super plants? We don’t currently know, but it seems that this should be an urgent topic for research. At the moment, perhaps the best option is to use Tallamy’s list for Brookings, Oregon. On that list, the best native trees and shrubs are willow (312 species of caterpillars); plums and cherries (240 species); poplar/cottonwood/aspen (227 species); alder (210 species); oak (200 species); pine (199 species); and crabapple (155 species).

Finally for some good news:we can make a difference. In our own landscapes we can start to address the problem of declining insects, birds, bees, and butterflies by planting more natives, especially super plants; by reducing the area covered by lawn; and by creating wildlife corridors to connect existing stands of native plants. When we do so, we reap an added benefit—these creatures literally animate our gardens, providing another level of interest and beauty. And by the way, Tallamy recommends “holistic” gardening: if your plants have holes in the leaves, consider that a good sign!

In his words, “You can make a beautiful garden that also supports local food webs, sequesters carbon, improves your watershed and helps pollinator populations all by yourself if you choose productive plants. And your contribution to local ecosystem function plays an important role in sustaining this planet.” Such gardens sustain us as well, enriching our lives with a stronger sense of place and the rewards of being attuned to natural processes and seasonal patterns.

Restoring Nature One Garden at a Time. Revised for formatting 2022.10

Books on Gardening with Native Plants

(compiled by members of the North Coast Chapter, CNPS)       February 2016

There are many books available on the native flora of this region, gardening with wildlife in mind, or developing a more sustainable approach. The list below represents some of the most current work on these subjects. All the books listed are available through the Humboldt County library system.

Bauer, Nancy. The California Wildlife Habitat Garden: How to Attract Bees, Butterflies, Birds, and Other Animals. University of California Press, 2012. Filled with tantalizing photographs, this book provides an inspiring overview of the “why” and “how” of wildlife habitat gardening as well as specific information on attracting birds, bees, butterflies, and other beneficial insects. The author advocates using a diversity of plants—predominately natives—combined with environmentally-friendly garden practices.

Bormann, F. Herbert, Diana Balmori, and Gordon T. Geballe. Redesigning the American Lawn, a Search for Environmental Harmony. New Haven and London: Yale University Press, 2001. Breathes new life into Rachel Carson. Includes a history of, and alternatives to, contemporary lawns.

Bornstein, Carol, David Fross, and Bart O'Brien. California Native Plants for the Garden. Los Olivos, CA: Cachuma Press, 2005. A comprehensive resource describing over 500 California native plants. Authored by leading native-plant horticulturists, this book covers landscape design, installation, and maintenance, includes 450 color photos, and contains information on where to view and purchase native plants.

Bornstein, Carol, David Fross, and Bart O'Brien. Reimagining the California Lawn: Water-Conserving Plants, Practices, and Designs. Los Olivos, CA: Cachuma Press, 2011. After a brief discussion of problems associated with lawns, the authors describe a variety of landscape alternatives such as meadows, rock gardens, succulent gardens, and edible gardens. The following section covers managing, reducing or removing lawns. The bulk of the book profiles a wide variety of drought-tolerant landscape plants—both native and non-native—and includes helpful lists of plants that are attractive to bees or hummingbirds; fast- or slow-growing; useful in coastal conditions; etc..

Francis, Mark and Andreas Reimann. The California Landscape Garden: Ecology, Culture and Design. University of California Press, 1999. An informative integration of garden design considerations and habitat types.

Keator, Glenn and Alrie Middlebrook. Designing California Native Gardens: The Plant Community Approach to Artful, Ecological Gardens.. University of California Press, 2007. Divided into 12 chapters based on communities of plants that naturally occur together. The book provides examples of conceptual and applied landscape designs for each community, including plant lists, descriptions and color photos, as well as practical advice for maintaining native gardens. Also includes a plant source list.

Pettinger, April. Native Plants in the Coastal Garden. Portland: Timber Press, 2003. An excellent guide for gardeners in coastal areas of the Pacific Northwest. Includes descriptions of plants and habitats, plant propagation techniques, natural plant combinations, and some design ideas.

Popper, Helen. California Native Gardening: A Month-by-Month Guide. University of California Press, 2012. Detailed information on sowing wildflower seeds and bulbs, planting, pruning, dividing, garden clean up, and dealing with pests on a month-by-month basis. A valuable reference, with good color photographs and vivid descriptions of native plants in bloom every month.

Robson, Kathleen A., Alice Richter, and Marianne Filbert. Encyclopedia of Northwest Native Plants for Gardens and Landscapes. Portland: Timber Press, 2008. This comprehensive reference—illustrated with nearly 600 color photographs and drawings—describes plants native to the Pacific Northwest. Discusses growing conditions, propagation, and much more.

Schmidt, Marjorie G., and Katherine L. Greenberg. Growing California Native Plants. University of California Press, 2012, 2^nd ed. A recently-updated workhorse on native plant propagation and gardening in California.

Smith, M. Nevin. Native Treasures : Gardening With the Plants of California. University of California Press, 2006. Provides practical cultural advice on CA native plants, including propagation, and design suggestions for varied garden styles. Includes gorgeous color photos and line drawings.

Stark, Eileen M. Real Gardens Grow Natives. Seattle: Skipstone, 2014. Presents a strong case for using native plants to support birds, bees, butterflies, and other insects. Covers design considerations, site preparation, gardening practices, and plant propagation. The heart of the book is a portfolio of 100 garden-worthy Pacific Northwest native plants, with color photographs and useful information on the growth habit and wildlife value of each plant.

Tallamy, Douglas. Bringing Nature Home: How Native Plants Sustain Wildlife in our Gardens. Portland: Timber Press, 2007. A passionate treatise that explains why using native plants is not just a nice idea but crucially important for the survival of wildlife. A must read for native plant lovers and all gardeners.

Water Conservation Staff, East Bay Municipal Utility District. Plants and Landscapes for Summer-Dry Climates of the San Francisco Bay Region. Oakland: East Bay Municipal Utility District, 2004. Although written with the Bay area in mind, the information in this 320-page volume applies equally to other Mediterranean-climate areas. Enjoy striking color photos of both native and non-native plants in climate-appropriate garden settings, plant lists, charts, descriptions, and practical advice on water conservation.

Books for identification of native plants (and insects)

Baldwin, Bruce, convening ed. The Jepson Manual: Higher Plants of California. University of California Press, 2012. A technical reference for professional botanists, this comprehensive text is written for those with knowledge of botanical terminology. A bit heavy to tote into the field, it includes natives and common exotic weeds.

Haggard, Pete and Judy Haggard. Insects of the Pacific Northwest. Portland: Timber Press, 2006. Over 600 beautiful close-up photographs of more than 450 common insects and non-insect invertebrates highlight the natural history text in this introductory field guide written and photographed by local authors. A “must have.”

Horn, Elizabeth L. Coastal Wildflowers of the Pacific Northwest. Missoula, MT: Mountain Press Publishing Company, 1993. 200+ color photos of common wildflowers and flowering shrubs (including exotics and invasives) found along coastal British Columbia to Mendocino, CA. Organized by habitat, it allows beginners to identify plant communities.

Kauffmann, Michael E. Conifers of the Pacific Slope: California, Oregon, and Washington. Kneeland, CA: Backcountry Press, 2013. A field guide for identifying the conifers of the Pacific slope, including Idaho, Nevada, and parts of British Columbia and Baja California. Includes color plates and range maps for 65 conifer species. Produced in association with the North Coast Chapter of the California Native Plant Society and the Humboldt State University Redwood Science Project.

Lanner, Ronald M. Conifers of California. Los Olivos, CA: Cachuma Press, 1999. Beautiful color photos and illustrations bring our state’s 52 native cone-bearing trees and shrubs to life. Includes tips on identifying conifers both from a distance and up-close, as well as information on habitats, natural history, and state-wide distribution of species.

Pojar, Jim, and Andy MacKinnon. Plants of the Pacific Northwest Coast. Vancouver, BC: Lone Pine Publishing, rev. ed., 2004. Although described as a guide to plants found from British Columbia to Oregon, it applies equally well to our portion of the state. Includes photos of mosses, lichens, grasses, and aquatics, in addition to trees, shrubs and wildflowers, and their historical uses.

Stuart, John D., and John O. Sawyer. Trees and Shrubs of California. University of California Press, 2001. A California Natural History Field Guide to the more common native shrubs and trees of our state. Written for both amateur plant enthusiasts and professional botanists (some knowledge of botanical terminology is helpful). Includes vegetative keys, clear descriptions and illustrations, and sixteen pages of color photos. It’s also small enough to toss in a backpack.

Turner, Mark and Phyllis Gustafson. Wildflowers of the Pacific Northwest. Portland: Timber Press, 2006. This comprehensive field guide describes and illustrates 1,220 commonly-encountered species, both native and nonnative, including perennials, annuals, and shrubs. It encompasses the Pacific Northwest from southern British Columbia to northern California, from the coast to the mountains and high desert. Organized by flower color and shape, and including a range map for each plant described, it is as user-friendly as it is informative.

Young, Dorothy King. Redwood Empire Wildflowers. Happy Camp, CA:Naturegraph Publishers, 1989. This is a locally classic handbook of 132 wildflowers of the Redwood Empire listed alphabetically by common names, with scientific names following. A brief description of each flower identifies characteristics, size, habitat, and the general locality and time that the flower may be found. Additional information includes a short discussion on conservation of wildflowers and suggested wildflower trips.

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