Backyard Habitat Restoration
We recently caught up with Master Gardener Guma, whose focus on habitat restoration is central to the way she gardens. With habitats disappearing in California and extinction pressures mounting, Guma urges all gardeners to become part of the solution.
Master Gardeners: Why is habitat restoration so important?
Guma: We are in an existential crisis: part of it is climate change, and part of it is a crisis of extinction, a loss of species. Scientists estimate a 45% decline in insect species worldwide, and a 29% decline in bird species in North America over the past half century. When people here think of extinction they think of wildfires, but the more persistent and deadly killers are pesticides, herbicides, and loss of habitat to overdevelopment. Collective action is necessary, but even a relatively small number of people can have an effect on preserving species. The Dawn Redwood tree was believed to be extinct for hundreds of years, but it turned out that one small village in China treated it as sacred, and preserved it. Now it is available as a landscaping tree. You may not think much of the bugs in your garden, but all birds, even seed eaters, are dependent on insects, especially caterpillars, to feed their young.
California has an amazing variety of plant communities and a lot of endemic species which are found nowhere else. The birds, bees, and butterflies evolved with them over eons of evolution together, and often don’t recognize non-native species as food. My garden consists of California natives and vegetables. I don’t use poisons and fertilize only selectively and minimally.
For example, the Dutchman’s Pipevine is the only place where the Pipevine Swallowtail butterfly will lay its eggs. The California Lilac (Ceanothus) will attract up to 117 species of caterpillars, while the Crepe Myrtle and Gingko come up with zero. I have seen a great variety of bees, birds, hummingbirds, snakes, salamanders, and frogs in my garden, plus one fat possum that comes around once a year when the California grapevine fruits.
I keep a brush pile in the back for shelter and have a recirculating water feature to provide water year-round. It’s important to plan for continuous blooming so that there is always food available. In spring that’s easy, but in the late dry season in California and the winter some blooming plants are crucial. I have a Chapparal currant that blooms in December, Pink-flowering currants and manzanitas that bloom in January-February, California fuschia and Woolly Blue Curls that bloom late into the fall. A ground cover called Lippia repens doesn’t even show in the spring but attracts lots of butterflies and skippers in the late summer.
Master Gardeners: How did you create this habitat?
When I moved into this house, the soil was “dead.” It was covered with a deck, weed-cloth, shale, painted wood chips, plastic mesh, and a few “landlord plants.” We ripped out the deck and eventually cleaned out all the artificial junk and sheet-mulched all the lawn areas. We had the existing soil dug into berms (raised areas) and swales (depressions), with the drip irrigation lines going along the top of the berms and the swales filled with wood chips for water retention. The roof drainage was routed into the swales, where the water has to take a roundabout path to the lowest point. Soil can retain a lot more water than any cistern.
We revived the soil with compost, mulch, gypsum, mycorrhizal innoculum (soil fungi) and cover crops. I continue to compost the vegetable beds but not the native plant beds, as natives thrive on native soil and don’t like soil that is too rich in nitrogen. The soil in the native beds is refreshed by simply letting plants go to seed and die where they are, which also provides food and nesting material for birds. The natives and the veggies are on nearly opposite watering regimens, since the natives are adapted to our summer-dry climate.
Gardeners traditionally plant according to aesthetic considerations handed down from times when we didn’t have to worry about extinction: How does this plant look next to that plant? Native plants grow in communities, physically linked by soil microorganisms, with similar soil, sun, and water conditions. There are interlocking food webs in any ecosystem, starting with the soil but not ending there. “Everything is connected” is not just a mystical belief; it is a scientific fact. Disrupt one part of an ecosystem and you will have cascading consequences way beyond what you can see.
Master Gardeners: What advice do you have for other gardeners?
Guma: Plant natives. Make sure water and shelter are available for wildlife. A lawn is a biological desert, but from the point of view of the pollinators, so are gardens filled with exotic ornamentals. If enough of us pay attention to habitat needs, we can create wildlife corridors where endangered and threatened species can make it between larger habitats that can support viable populations. We might even save some small but crucial members of the ecosystem from extinction!