Bringing Nature Home: Fostering Biodiversity in Your Own Backyard

06/30/2010 05:12 am ET | Updated May 25, 2011

Douglas Tallamy, lifelong bug lover, made a striking discovery in his yard a few years ago: he noticed that his ornamental plants were not attracting any bugs. The observation seems innocuous enough--especially since so many plants sold for beauty boast an adverse taste to "pests"--but it was actually an incredibly meaningful discovery. It may seem hard to believe, but this very fact led Tallamy to the conclusion that everyone with space for a garden is ultimately responsible for the biodiversity of his or her local community. Indeed, according to Tallamy's argument, we can save the declining numbers of insects, birds, rodents and mammals that currently threatens to destroy our food web, simply by making better use of our lawns.

As it so happens, Tallamy is not just any bug lover: he is professor and chair of the Department of Entomology and Wildlife Ecology at the University of Delaware. He has been observing bugs all his life and is highly attuned to their role as food for larger, more conspicuous animals that we've come to recognize as emblematic of our back yards: rabbits, blue jays, frogs, foxes, etc. But without bugs, the creatures we associate with the American pastoral will cease to exist. And though human beings like to believe they can proliferate in isolation from other species, it's not possible. Our race would exist a few short years without a sustaining ecosystem to support it. Dire though the consequences of a bug-less world would be, Tallamy argues that it's quite feasible to rehabilitate lost populations of insects and animals. The effort is not just imperative: it's appealing.

Highways, high rises and parking lots are some of the major causes of habitat fragmentation and the resulting loss of biodiversity. Another--which many of us enjoy--is the great expanse of sterility known as the suburban yard. The suburban aesthetic is playing a huge role in the destruction of native plants and animals nationwide. There is exactly a 1:1 correlation between the amount of habitat and the species that can exist in that habitat: meaning, if we destroy 80% of a habitat--places where species can nest, feed, and move freely--we will lose 80% of the biodiversity in that space. And even though most Americans favor green around their homes, most of what we're growing is not feasible eating or housing for the bugs that feed our favorite animals, which are disappearing at alarming rates.

Not everyone loves insects as much as an entomologist, but nobody wants to see Monarchs disappear or birds decline any more than they already have--at a rate of a 50% reduction in population size for many American species within the span of 50 years. As Tallamy puts it, "Butterflies cannot find their host plants, egrets cannot hunt the fish they eat and hummingbirds cannot find the nectar they need to survive..." And yet, so many Americans enjoy green back yards, plush with beautiful trees, shrubs and pest-free flowers.

So what's the problem with buying ornamentals labeled "pest-free?" As Tallamy discovered, these beautiful, bug-less foreign plants are choking off habitat space by not attracting native species: bugs that grew up in Delaware don't want to eat maple leaves from Kyoto. More scientifically, insects evolved in sync with local plants, and are digestively equipped to break down the unique chemical make-up of similarly native plants. As a result, insects cannot recognize non-native plants as food, and therefore, lose the most critical component in their habitat when a native plant is replaced with an alien one.

Another correlation is at work: the number of plant and animal species in any given ecosystem is directly proportional. In order to sustain the largest number of insects--which will feed the greatest number of other species--there must be a varied number of native plants available for insects to eat. As Tallamy puts it, plants are the first trophic level of the planet--"the energy that sustains all life." Attracting the second layer of trophic life requires providing adequate bait: namely, bugs. Bugs, as it turns out, have more protein than beef, gram for gram, and are one of the most efficient ways of converting plant energy into concentrated calories for birds and animals.

Creating more sustainable habitats is critical, and unlike so many daunting environmental dilemmas, it is feasible for the average person to make a significant, and notable difference. By replacing non-native (and typically invasive) species with those that can support local wildlife, the average American homeowner can help foster and strengthen habitats: currently only 3% of our nation's landscape is untouched by development. As a result, habitats have been fragmented into dangerous "islands," where species exist in small, isolated numbers, putting them at risk for collapse should any imbalance or illness occur in their small space. But by fostering a healthy, balanced population of native plants, individuals, families and entire neighborhoods can restore a truly precious and precarious balance to the natural world.

This effort doesn't mean letting your front yard turn into an untended mess. In fact, landscaping with natives can be just as complex and artistic as using non-natives. Tallamy suggests planting in tiers, and using the natural mulch from leaves rather than expensive, store bought stuff. In fact, he even suggests using your alien plants as mulch when the die and replacing them with natives that are similar in size, shape and texture. Trees are especially effective at sustaining wildlife. High at the top of his list for most regions in America include oaks (which can support an average of 534 species); willows (456); cherry trees (456); birch (413); poplars (368) and maples (285). Tallamy has seen acorns turn into five-foot specimens in the course of four years. Also essential are lower-levels of densely planted natives including red or black cherokeberries and native azaleas, as the shrub-layer is where birds most often nest. Coincidentally, creating a tiered visual space is exactly what traditional landscaping calls for.

Consider the rewards of an effort to create a more diverse and hospitable environment for local species: not only can the backyard reflect what it looked like before it was razed, built on, then landscaped, but it will also attract essential creatures to life as we know it, building a bridge with the natural world and species otherwise unnoticed, and possibly, unknown. Much of what you need to know about planting natives can be found in Tallamy's website and book, Bringing Nature Home.