Biodiversity in Vineyard Management:
Beauty, Structure, and Micro-Biomes
Winemaking may evoke images of barrels, of full tanks and grape skins floating in a seething mass of fermenting wine. But just as often as we may think of process and aging, we picture the sprawling rows of vines that stretch over sunny hills, contouring their every crest and trough. The bucolic image of the vineyard is one that almost automatically evokes a sense of a slow-paced mediterranean life filled with tradition and simple rituals punctuated with long lunches where a glass or two of wine isn't frowned upon, but considered culturally appropriate.
When we zoom in, though, the poetry of this sun-parched and romantic agrarian lifestyle transforms. Our perspective changes from one of generalizing a lifestyle to the specifics of how many small components accumulate and collaborate to create a micro-biome that does more than just produce one of our cultures most revered alcoholic beverages.
Here at Shelburne Vineyard we've made it our mission to look at the details of our land and how we manage it that affect both the microscopic scale of the soil health around one individual vine and on the macroscopic scale of both our local environmental health and our global climatic health.
In our field, the practice of cultivating or promoting growth around your vines or between the rows is known as Floor Management. This is a broad term that describes both the laborious and time-consuming practices of cultivating flora in the vineyard as well as the passive practice of promoting endemic flora to proliferate in and around the vines.
New England has a plethora of vigorous and prolific undergrowth. If you've ever passed through Vermont in July or August, you'd know how dreadfully your allergies can flare up. The sheer volume of wildflowers contributes to a dip in air quality in the summer months that can leave us unhappy and a bit drippy. For us at the vineyard, however, these plants play an integral role.
There are a number of reasons why one allows for these misunderstood "weeds" to creep up and down the rows. For one they provide biomass that helps stitch together our soils and prevent erosion. When a vineyard is managed conventionally, rows are often mowed down to the soil below. This exposes the soil to the potential for wind erosion and reduces its ability to retain moisture. On top of the potential for increased soil erosion, trimming your rows down to the bones creates a more porous membrane through which any chemicals introduced into the vineyard will pass more easily. Finally, the biomass from a year of wild growth will eventually pass and become the decomposing materials that will reintegrate and nourish the soils for the years to come.
In addition to contributing to soil structure, the endemic flora creates a safe harbor for other beneficial organisms to flourish. These include insects, microbial organisms, and mycorrhizal fungi. Microbes and mycorrhizal fungi are both hidden beneath the topsoil and aren't apparent to the human eye. But when it comes to the benefits it imparts to the soil and the vines themselves, their usefulness is outsized.
Mycorrhizae are the fine mesh network of fungi that exist in symbiosis with the root networks of plants. These networks have existed for hundreds of millions of years and have been aiding in plant nourishment since the dawn of time. They aid in water, sugar, and mineral absorption and have the ability to transport nutrients across plants through their broad hyphae networks.
Microbes are a litany of microorganisms that serve primarily to decompose the biomass that we cultivate between vineyard rows and make the nutrients available for re-absorption.
The mechanism that a diversity of endemic flora contributes to fungal and microbial diversity is linear; more variety begets more variety and a diversity of micro-assitants is going to promote general soil health and contribute nutrients back into the soils of our vineyard.
General predatory insect presence in any gardening or agricultural operation is considered auspicious. Arachnids in particular, which fall further up the food chain, are welcome additions to the vineyard. They're impact on various beetle populations that chew through canopy cover is a positive one. These handsome helpers would find themselves less at home without the additional cover provided by the undergrowth.
Economic incentives are built into a naturalistic approach to floor management. Fewer tractor passes in tilling and mowing means lower carbon emissions and fewer dollars spent on the labor to maintain the rows. This natural reduction in overhead is a welcome one especially as harvest rolls up and we want more resources to complete harvest professionally and expeditiously.
The presence of more competition in and around the vine also reduces the vigor of the canopy. Especially in the case of the hybrids we grow, these vines can become unruly when left to their own devices. A small amount of strain in and around the root structures of the vine lessens the vigor of the vines' annual vegetative growth a reasonable amount.
We at Shelburne Vineyard practice a small amount of Cover Cropping. This phrase refers to a more explicit cultivation of specific crops in specific areas for specific reasons. We practice cover cropping with ryegrass and buckwheat around our Riesling vines. When it comes to be later in the season, we are able to pass through with a scythe and incisively remove the cover crop. This will have prevented the growth of more unruly flora from settling in and makes the soil beneath the vines more pliable and accessible when it comes time to mound soil around the graft point to preserve the vines through the winter.
All of our growth gets cut back at some point, though. Whether it be midsummer to allow for more airflow beneath the canopy of the vines to prevent moisture accumulation, or whether it be before harvest to just make it easier to move up or down the rows. That said, the biodiversity that ebbs and flows throughout the season is essential in bolstering soil health and improving biodiversity in the micro-biomes that are our vineyards.
The result? Great fruit that hasn't experienced exposure to herbicides or insecticides, yet still has survived beautifully due to the plethora of helping insects, fortifying plants, and beneficial soil-dwellers.