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Here follows
an account of the keynote address author Doug Tallamy presented
at the Virginia Native Plant Societyís 2009 annual meeting:
Bringing Nature Home —
How Native Plants Sustain Wildlife in Our Gardens
The weather
was dreadful, but ... we didnít let it keep us indoors. A highlight,
however, was the (indoors) keynote speaker on Saturday night, Doug
Tallamy, author of Bringing Nature
Home (and University of Delaware professor in his spare
time). If you donít have this book, get it now. Itís out in paperback.
I have bought four copies so far and only kept two; one went to
an environmental sciences high school teacher... who said it was
mind-blowing.
Doug spoke
eloquently about the problems in modern society and their impacts
on the environment. At one point, he summed it up by saying that
most of us feel that ěNature is well and happy someplace else.î
While we, in contrast, are well and happy in the center of our ěsterilizedî
lawns and (mostly nonnative) landscapes.
Iíll just
summarize a few of his best (IMHO) points:
1.
In healthy ecosystems, there is a lot of redundancy;
niches and positions in the food web are covered by more than one
species or organism. However, with the lower biodiversity of most
of our suburbs and developed areas, the redundancy is lost; when
one species or niche disappears, the whole food web crashes.
2. Where
there is more plant diversity there is more animal diversity.
Biodiversity is an essential, non-renewable resource.
3. There
is such as thing as ěfunctional extinctionî when population
numbers of a particular plant/animal in an area get so low that
they are not able to perform their function in the food web/ecosystem.
If one were to claim that because there are no documented examples
of extinctions due to nonnative invasives, that claim would be not
only largely irrelevant, but also wrong (Tallamy says that there
are, indeed such examples on islands). So there.
4. Only
native plants are part of the food web. He defines ěnativeî
as being an organism that shares an evolutionary history with the
species in a given area. For example, many caterpillars can only
survive and reproduce in the presence of three or fewer plant types!
Thatís because those caterpillars have co-evolved in the presence
of a specific plant to be able to digest its leaves despite the
defensive toxins that the plant has developed to protect itself!
5. When
we buy and plant nonnatives, we are depriving wildlife of food;
a ěpest-resistantî plant is a food-free plant. For example, the
ěbutterfly bushî only supports ONE species of butterfly. Sure, more
species feed on the nectar, but when it comes time to reproduce
and make more butterflies, the butterfly bush is virtually useless.
Oaks, on the other hand, support over 500 species of butterflies.
6. Moving up
the food chain, this matters because birds need
insects (incl. caterpillars) to feed their young. They
cannot raise their nestlings on seeds and nectar. The protein in
insects is very high quality and absolutely essential for baby birds.
So, says Tallamy, without (native) insect host plants, ěwe feed
the birds all winter and then starve them in the summer.î
7. In
general, woody plants support far more biodiversity than herbaceous
plants. But both are necessary for habitat.
8. Regarding
nonnative invasives: Japanese honeysuckle, for example, was
used in landscaping for 80 years before it started to become invasive.
Itís not known how/why that happened, but it means that we
canít know in advance if something will eventually cause problems.
9. Finally,
in answering my last-minute question, Tallamy confirmed that the
notion of ěkeystoneî species is of only limited usefulness
in protecting habitat/food webs. ěAnything can be a keystone species
in the right circumstances.î
In an hour-long
presentation, he gave us more information (and ammunition, frankly)
than we could really take in. The room was so quiet you couldíve
heard a pin drop. He ended with several slides about how we need
to take these messages to our suburban environments and turn them
back into places that we share with nature and wildlife.
A suggestion
was to take 50% of the lawn acreage of every yard and plant it with
natives (and do a good job if possible; leaf litter, variety
of plants, habitat elements, etc). Connect the yards with hedgerows
and contiguous planted areas.
It wonít obviate
the habitat fragmentation/edge impacts, but it could be a huge improvement
over what we have now. And conserve a heck of a lot of water in
the bargain. And provide living outdoor spaces for us and our children.
Amen. ó Kathi Mestayer, reprinted with permission from Claytonia,
the newsletter of the John Clayton Chapter of the Virginia Native
Plant Society
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