A Hedge-what?
"What is a hedgerow?" I'm often asked when promoting this obscure landscaping device.
"Why, it's a home for hedgehogs!" I reply. Or if my I'm in a completely facetious mood, "It's a row of hedges, of course!" Or, for my high-brow plant friends who know that a 'guild' has nothing to do with gold and that 'forbs' aren't magazines about money, I might say, "A hedgerow is a guild of linearly planted trees, shrubs, forbs, and grasses."
All of these answers are true. But today I would like to delve into an answer and take a more serious look at what hedgerows have to offer. In short, hedgerows play a key role in our history and may be the solution for saving the farm, reversing climate change, and keeping you and your kids healthy.
The Neolithic Hedgerow
To really understand hedgerows, let's look at their humble origin. Hedgerows date back thousands of years to the dawn of agriculture. Like many amazing and useful things, early hedgerows were more the product of accident than human ingenuity.
The hedgerow began with the domestication of crops and animals by Neolithic humans. As crafty as Neolithic humans were, they invented the cow and wheat before inventing the fence. In their haste to protect the first invention from devouring the second, they chopped and piled whatever they could get their stone axes into.
Their crude solution for a fence had problems: dead wood rots, burns, and needs constant upkeep. But accidents were on their side! Maybe some of the plants they chopped were thorny. Maybe some were less palatable to the newly domesticated cattle — leftovers on grazed land. Maybe, just maybe, some chopped plants were prone to easily reseeding and resprouting from cuttings. How much was accident and how much was horticultural planning is debatable. In any case, these original fences grew and the hedgerow was born.
Eight thousand years later, in our day of the fierce and durable barbwire, it might seem that the hedgerow is a relic of the past. Make no mistake, though some have! The hedgerow has not faded from use, though in Europe thousands of miles have been removed to make way for development in the last few decades. In California the hedgerow is experiencing a small renaissance — the humble hedgerow is the subject of research and innovation. At least a small group of hopeful people are actually spending their time thinking about the hedgerow, about how to make it better, faster, more beautiful!
Johnny Appleseed of the Hedgerow
As in the beginning, hedgerows today function in agriculture. A bastion of progressive hedgerow thought is found at the Community Alliance for Family Farmers (CAFF). Sam Earnshaw is one of the ringleaders of this group and an award-winning advocate for hedgerows. Sam has a beard thicker than some hedges, and eyes that twinkle when he talks about them. Sam is responsible for the planting of more than 100 miles of hedgerows on more than 70 farms in California. He and the folks at CAFF believe in a world where agriculture and nature more than exist together, they actually support each other. To this end CAFF has developed an exceptionally detailed and practical handbook that anyone can use to get a hedgerow of their own going (see references below). The handbook defines the hedgerow as far more than a crude barrier on the farm or ranch. Rather, it is a nuanced and sophisticated piece of machinery disguised as a blooming, booming pocket of nature. In the right circumstances, a hedgerow has the potential to save the farm.
First, there are the obvious benefits of the hedgerow. It is beautiful! It provides habitat to harbor the diversity of life. Its deeply rooted vegetation stabilizes soils—all things just about any bunch of bushes could do. But many farms have looked deeper into the possibilities.
One of these uses is as habitat corridors. One of the major threats to the longterm survival of wildlife — as much as habitat loss — is habitat fragmentation. Habitat fragmentation happens when roads, farms, or other developments create islands of habitat. Essentially ship-wrecked populations of animals become more vulnerable to localized extinction. Besides adding to the actual quantity of habitat, hedgerow corridors bridge disjointed habitats. Corridors relieve the environmental pressures of a single fragment of habitat, as birds, mammals, and insects can reach new breeding and feeding grounds. This is a good thing to do! But, it is also practical.
The Glorious Anagrus epos
Meet Anagrus epos, a tiny wasp that calls the hedgerow its home. If you're a vineyard, Anagrus epos is one of your best friends. This tiny wasp makes its living parasitizing the eggs of the grape leafhopper, a vineyard pest. The leafhopper drinks the grapeleaf juices and poops on the grapes — not a mark of great terroir.
Agriculturalists understood this relationship between the wasp and the leafhopper and attempted to use A. epos as a pest control by releasing populations into the vineyards. These trials proved effective, but when winter came, the wasps died and did not reappear. A. epos needed a year-round food supply, and the leafhoppers stopped reproducing during the winter, leaving few eggs for the wasps to eat.
A couple of observant researchers noticed that vineyards near creeks did harbor A. epos over the winter. They realized that A. epos fed on another type of leafhopper there — the blackberry leafhopper — which continued laying eggs in winter. The blackberry leafhopper doesn't harm grape plants. Importantly, the researchers also noticed that areas of vineyard near the creeks or prune orchards were repopulated with A. epos quickly in the spring. Since leafhoppers reproduce many times in a season, killing one egg can effectively kill multiple generations, stiffling population booms. The blackberries and prunes acted as habitat by providing a diverse food supply for the wasp throughout the year. Also key, the creek served as a habitat corridor, allowing the wasp to disperse into the vineyard all along the creek quickly when grape leafhoppers appeared in spring.
Later, researchers found that A. epos also fed on prune leafhopper eggs, which live in prune trees, reproduces all winter long, and also doesn't harm grape plants. Since then, hedgerows containing blackberry and prune have been used in hedgerow plantings to harbor and diffuse A. epos throughout the vineyard. The agricultural name for these hedgerows is an insectary, or plants specifically chosen because of their association with the predators of farm pests. Some insectaries have a variety of plants so that one type of plant is in bloom all year round, providing food sources for pollinators and omnivorous insects that drink nectar and eat other insects. Besides food, insectaries provide year-round shelter, critical for certain kinds of predatory beetles and spiders. Serving actively as refuges for good insects, hedgerows also displace weedy areas that have been shown to harbor pests—insect and rodent—as well as serve as a source of weed-seed on a farm. Most ecological certifications, including CCOF Organic Certification, Central Coast Vineyard Team's SIP, Demeter Biodynamic Certification recognize the hedgerow as a conservation tool.
The Controversy of the Hedgerow
The hedgerow, humble though it may be, proves that anything can be a point of controversy. Some even view it as a haven of filth and degeneracy. Recent food safety laws endorse a scorched-ground policy surrounding fields of produce—directly contrary to the ethics of diversity. Hedgerows attract wildlife, which are viewed as vectors for E. coli and other food-borne illnesses. In truth, there is very little evidence for these views. In truth, the real E. coli haven is ensconced right at the heart of the industrial food supply—in enclosed animal units such as cattle feedlots. Farms that use this manure, or have dust or runoff enter their fields from nearby feedlots are at a much higher risk of contamination. Hedgerows may intercept and filter contaminated dust and runoff, protecting crops.
To Be Continued...
You don't have to be a head of lettuce to appreciate the virtues of a hedgerow. Read this column next month and find out even more about multi-functionality of the hedgerow as it moves out of the field and into the city, battling climate change, cutting utility bills, and saving your children!
Coming in May, The Golden Age of Hedgerows, Part II...
References
Greig, J. "A possible hedgerow flora of Iron Age date from Alcester Warwickshire." Cirazea, The Journal of the Association for Environmental Archaeology. Volume 11, no. 1; pp. 7-16.
Sam Earnshaw
CAFF's Hedgerow Resources
Pickett C.H; Bugg R.L. Enhancing biological control: habitat management to promote natural enemies,University of California Press. Nov 20, 1998; pg. 298.
Thrupp L. A.; Costello M.J.; McGourty, G., Biodiversity Conservation Practices in California Vineyards: Learning from Experiences. Bulletin from the California Sustainable Winegrowing Program. March 2008.
California Leafy Greens Regulations
University of California, Establishing Hedgerows on Farms in California
