Garden Notes
The Martha's Vineyard Agricultural Society's (MVAS) 148th annual fair has come and gone. Thanks to all who participated. Entries were up this year over last. Reviving agriculture by producing and growing, participating in the Fair, and supporting local farms - these are measures individuals can take to contradict the cynics prophesying the death of Island farming and way of life.
Fair entries like this delectable display of vegetables proved that resilient Island farmers had overcome the challenging growing conditions early in the season. Photo by Susan Safford Congratulations to those who won ribbons in their categories. It is exciting to see how large the youth gardening categories are becoming. Among adult gardening categories several newer gardeners exhibited beautiful produce and won ribbons. This year challenged many gardeners' patience, waiting for the rain to stop and the sun to shine, for example, but the activity creates its own rewards (see photos), irrespective of ribbons won.
To those who intend to join the Society and gain free admission to the fair - do it now for 2010. You cannot support an organization more uniquely Island-themed than MVAS; and memberships, both annual and lifetime, are the most uniquely Island-themed gifts for your Island associates, family, and friends.
Biodiversity: What does it mean?
I planted three Cornus alternifolia (pagoda dogwood) saplings two years ago. The plant is native to North America, from Newfoundland to Minnesota, southward to the extreme southern Appalachians, and westward to Missouri. It tolerates more cold, wind, and alkaline soil than Cornus florida and is a beautiful small tree to add to the understory.
Admiring their growth this morning, I was startled to see that one, the most vigorous of the three plants, was being skeletonized by something. Fall webworm? No, the leaves were heavy with many dozens of small yellow, black, and white striped caterpillars coiled together in masses. I rushed to "Caterpillars of Eastern North America" (David L. Wagner, Princeton Univ. Press, 2005), and the Internet.
It is thrilling to hope that my defoliators are larvae of the Prometheus moth, Callosamia promethea. This member of the giant silkworm moth group, subfamily Saturniinae, becomes a moth with a wingspan of about four and a half inches. Wagner describes early instars (growth stages) as gregarious and transversely banded with yellow and black. Later the larvae molt to large greenish caterpillars with four bright red, hard-to-miss doodads on the head, and begin to feed solitarily.
As many amateur lepidopterists are aware, southeastern Massachusetts and the islands are one of the last strongholds of this spectacular group of moths - including the luna, the polyphemus, and the cecropia moths - which were formerly much more common. Their prefer as food plants various trees and shrubs of forest habitats and find them, as well as their mates, by scent. Massachusetts has lost much of that habitat within the lovely large moths' range.
But what if I had found some less glamorous species of caterpillar, such as fall webworm, defoliating the Cornus alternifolia?
Connecting the dots, Prof. Douglas Tallamy, chairman of the department of entomology and wildlife ecology at the University of Delaware, gave the recent David Smith Memorial lecture at the Polly Hill Arboretum. Entitled "Bringing Nature Home," (also the title of his best-selling book, published by Timber Press, Portland, 2008) Prof. Tallamy demonstrated how ornamental planting of alien species has widely dominated suburban/urban ecosystems, rapidly undermining the interlocking webs that constitute the food chain.
If the bottom of the food chain collapses, so must its upper levels.
If we want the numbers of species of birds, moths and butterflies that were common in the recent past, we need to take another look at what is growing around us and at our own gardening and landscaping practices. The following is the website (I hope you will visit it) that explains Prof. Tallamy's work, bringingnaturehome.net/native-gardening.
"If alien ornamentals are not the ecological equivalents of native species, particularly in their palatability to herbivores that transfer energy to higher-level consumers, herbivore productivity, as well as the biomass of organisms that depend on herbivores will be compromised in landscapes in which alien plants comprise a large portion of the plant biomass."
What this means: the breadth of biodiversity of our environment is directly supported by what grows on our properties, lots, gardens and yards. It is not all "just the same." Find the lists of herbaceous and woody plants on the website and the numbers of species they support. At the top of the lists are Quercus (oak) 534, Prunus (cherry) 456, Solidago (goldenrod) 115, and Asters 112, the very plants common to island land that are apt to be cleared away to make room for velvety lawn and European-style gardens embellished with exotic shrubs. These landscapes support very few species.
The herbivores' food sources must have the right combination of chemical or scent characteristics for the herbivores to find them, a case in point being the so-called milkweed butterflies. The females of Queens and Monarchs lay their eggs on the preferred food plant, milkweed, and the larvae concentrate the food plant's toxic compounds to repel predators!
The herbivores have evolved to feed on certain plants; in turn they feed the next level, insects, birds, reptiles or amphibians that have evolved to feed on the herbivores: the web of life. Maintaining it means refraining from automatically killing the insect life we find on our plants or properties ("What are these worms on my trees? What can I spray on them?"). Almost all terrestrial bird species feed their young on insects.
Some of my clients are very interested in butterflies and their habitats. They get it: it is fun to share with these enthusiasts the munching on the parsley or dill of the Swallowtail caterpillars, or the messy webbed shelters of the American Lady caterpillars among the helichrysum and pearly everlasting.
