Last weekend the Western New York Land Conservancy and Erie County Master Gardeners hosted the leading American spokesperson for ecological health, Douglas Tallamy. His messages are crucial for everyone, but he was speaking largely to audiences who already care about ecology and environmental issues. It’s my job to tell you about it – and your job to help me and professor Tallamy spread this crucial understanding.
First, let’s catch up with the basics:
There is very little “nature” left. About 94 percent of people live in cities or suburbs. About 84 percent of the land east of the Mississippi is privately owned (with similar numbers in the other half of the county). A large percentage of so-called “open space” is in agriculture, used for mono-crops (corn, soybeans) or grazing, where biodiversity is scant.
Huge acreage is paved for highways, malls, sports or other non-residential purposes. Much so-called “greenspace” is mostly turfgrass, used for running, biking, or other human activity, and it has little or no ecological value. Where we have anything resembling natural habitat, as in parks and rural property, it is fragmented with so little connectivity that genetic diversity is disappearing. Also many species require specific expanses of acreage for survival.
Bio-diversity, as in a rainforest, is the secret to survival of life on the planet as we have known. But we humans have altered or degraded at least 60 percent of the earth’s eco-systems.
Where then do we go from here? As scientists, leaders, gardeners, or just caring citizens, what can we do to achieve the least worse outcomes? We can’t go back to Longfellow’s forest primeval (and most people wouldn’t want to), but we can make positive choices at home. And remember that private citizens own most of the land: Our yards must become the habitat and support eco-systems.
Bio-diversity and native plants
When I wrote “Great Garden Companions” (Rodale Books) 20 years ago, I was promoting the idea that diversity is the key to a healthy organic garden. If you avoid mono-cropping, and plant vegetables together with herbs and flowers in certain combinations, you will attract and keep beneficial insects around (and birds, frogs, amphibians etc.) The community of predators and prey will handle most pest problems.
Mixed, diverse planting covers the ground, supports pollinators, and thwarts weeds. Building healthy soil and banning pesticides were/are the other tenets of the system.
Such “companion gardens” are a microcosm of what happens in nature ‑ to a point.
Then came the invasive species threat. Soil and Water Conservation leaders, forest biologists, Cornell educators and others were actively teaching that non-native invasive species were out-competing native species (plants and animals) and destroying habitat. Why? Because away from their own lands (where they are eaten) some plants can thrive and spread rampantly here ‑ where they have no natural enemies (nothing that eats them).
Statistics are overwhelming, but the loss of habitat, the spread of invasive species, exacerbated by climate change, are causing species extinction at 1,000 times the natural rate. (Data: U.N. Convention on Biological Diversity 2010).
Some 432 species of North American birds are at risk of extinction; we have 1.5 billion fewer breeding birds than 40 years ago; the lists go on. (Read: State of the Birds, 2016).
Understanding this, naturalists and horticulturists passionately promoted native plants, opposed non-native invasive plants, and pressed for bio-diversity in our fields, forests, and yards. We argued that native plants belong here, and generally do well in the soil and climate where they originated. We were right to press for native plants, but we didn’t yet have tools to make the strongest case.
Enter Douglas Tallamy
It is rare for great numbers of gardeners, educators, and experts to proclaim in unison that one guy turned their heads around, but this mild-mannered professor of entomology (University of Delaware) certainly did so. WNY Land Conservancy’s Nancy Smith, wildflower lecturer Lyn Chimera, and I are examples of many who changed our teaching and goals based on his book, “Bringing Nature Home” (Timber Press).
This is the lesson in its simplest form: Insects are the foundation of the web of life. Many of our native insects (that feed the fish, birds, amphibians) are leaf-eaters (or they eat leaf-eaters). What leaves can they eat? Insect herbivores must have the plants with which they co-evolved over millions of years.
This is key: Without insects, eco-systems collapse. Native insects must have native plants.
So now we know: Bio-diversity is not enough. We want diverse plantings - but we must use native species. Even if it’s just a portion of every property, let’s add as many natives (and lots of other pollinator plants) in our flower-filled yards in Buffalo, and around our suburban and country homes.
Let us also support organizations such as the WNY Land Conservancy that invest in habitat restoration projects such as the Niagara Gorge Restoration and the Stella Niagara Preserve.
Not all native plants are equal
We learned another important truth: Some plants, called “keystone plants” are far superior for the “eco-system services” they offer. Tallamy and his entomology students count and analyze the specialized relationships between insects, birds, and plants, as in this example.
Chickadee case study
Like 96 percent of terrestrial birds, chickadees rear their young on insects. The insects that baby birds can eat are caterpillars ‑ soft and digestible. The Carolina chickadee requires 5,000 or 6,000 caterpillars to rear a clutch of three babies for about 16 days. One pair of birds delivered a caterpillar every three minutes (including 17 species). Other counts showed the parents flying in with 400 to 570 caterpillars daily.
And where are the caterpillars? They’re on native trees (where you’ll never notice them), such as white oaks, wild cherries, willows, and birches. They must be nearby, or the exhausted parents won’t find the food. Choose these trees and help the birds.
The chickadees are just one little representative group, just as monarch butterflies are symbols of hundreds of other important, endangered species. The human footprint has made most “nature” unsustainable unless we actively assist.
This has been heavy news, but next week I will focus on plant choices and steps to take in our own yards. Read on!
Sally Cunningham is a garden writer, lecturer and consultant.