by Karl H. Kazaks
NRCS recently hosted an online program on the importance of biodiversity to agriculture and how organic agriculture tends to support increased biodiversity. The event was part of a series exploring the environmental benefits of organic agriculture.
The occasion was part of the USDA’s broader effort to educate the agriculture community and the public at large about organic agriculture, with the aim to increase organic production.
Said Betsy Rakola, the USDA’s Organic Policy Advisor, “The USDA has a strategic goal to increase the number of certified organic operations here in the United States.”
The program’s feature presenter was Dr. John Quinn, Assistant Professor of Biology at Furman University, in South Carolina. For his doctoral dissertation and postdoctoral work, Dr. Quinn studied how organic agriculture affected bird populations in Kansas and Nebraska.
According to Quinn, his “passion” is studying “how to protect biodiversity beyond protected areas, in particular in organic agricultural systems.”
Biodiversity is important of course to all agriculture and to all life, but within the context of U.S. agriculture policy, the National Organic Program standards have an explicit reference to the importance of preserving biodiversity
But what is biodiversity? Quinn acknowledged that it’s “a broad, catchall term.” The Convention on Biological Diversity defines biodiversity as “the sum total of all biotic variation from the levels of genes to ecosystems.”
Farm systems can be understood to have two types of biodiversity: planned biodiversity and associated biodiversity.
Planned biodiversity comes from “deliberate choices made” by farmers, Quinn said. Associated biodiversity comes from things beyond a farmer’s control. Examples of planned biodiversity include crops, cover crops, livestock, windbreaks and grass margins. Examples of associated biodiversity include birds, insects, weeds, soil biota, riparian areas and natural areas.
Biodiversity conservation often focuses on associated biodiversity, Quinn said. But the two types of biodiversity are connected and should be considered within a unified system of understanding.
“Decisions about planned biodiversity create conditions that affect associated biodiversity,” Quinn said.
What’s more, biodiversity is important specifically within the strict context of planned biodiversity.
Take, for example, the importance to agriculture of genetic diversity. The broader the pool of available genetic material, the greater the chance plant breeders will be able to produce cultivars needed by agronomy today (such as drought-tolerant varieties, or varieties better adapted for organic management.)
It’s possible, Quinn said, to measure the benefits of planned and associated biodiversity. Studies have shown that ecosystem services provide an annual value of $145 trillion. Biodiversity is a component of ecosystem health, with pollination, erosion control, and soil formation all being “essential components to a healthy farming system.”
Quinn did note that there are also ecosystem dis-services, such as pest damage, habitat loss and nutrient runoff.
Biodiversity can be measured a number of ways. Richness, or the number of species, is one metric. Abundance, the number of individuals within any one population, is another. Evenness – the relative abundance of various populations – is a third. You can also measure factors like breeding success as way to gauge a system’s health.
If biodiversity is important to ecosystem functioning, it makes sense to study agriculture’s impact on biodiversity, Quinn said, because agriculture uses forty percent of the terrestrial ice-free surface.
You can even measure the biodiversity of planned systems. For example, in many regions the variety of crops being grown has diminished, as the acreage of corn and soybean plantings has risen. Historically important crops like barley, wheat and sorghum are in many places grown on a declining number of acres.
Quinn cited a number of studies that, after comparing organic to conventional agriculture, made conclusions about the importance of organic agriculture to biodiversity. He did stress that such comparisons must be done in a related context – comparing systems in similar landscapes, since there is a connection between planned and associated biodiversity. What follows are some of the important findings.
In organic agriculture, there is a greater abundance and richness of birds, plants, and pollinators, with the greatest increase in richness coming in plants. The number of functional and cover types is also greater in organic systems.
In both conventional and organic agriculture, the richness and abundance of species is greater on field edges than in the center of fields.
Compared to conventional agriculture, organic agriculture has greater fungal richness, fewer pests and a greater abundance of predators. But the evenness of arthropods is also greater in organic agriculture (so those predators have a better chance of keeping other predator populations in balance).
The ecosystems services that ware greater within diversified systems (such as typically found in an organic system) are, inter alia, improved soil quality, carbon sequestration, water-holding capacity, energy use, pollination, and control of weeds and pests.
The impact of organic systems on biodiversity can be even greater than has been measured heretofore. That’s because some species respond to changes on a local, farm-level scale, while others respond more to changes on a regional scale. So as practices shift more broadly, it can have a greater impact (negatively or positively) on biodiversity.
The net result of all these conclusions provided by Quinn is that there is a clear benefit to biodiversity from organic agriculture. The challenge is how to maintain food production at a comparable level to that already achieved under conventional systems while adopting or altering practices that will benefit biodiversity and maintain and increase ecosystem services.
There are a myriad of practices that can be considered – from the use of cover crops, the planting of buffers, the reduction of the use of pesticides – but those topics were beyond the scope of this particular presentation.
But that information is out there. To learn more about it, visit your local NRCS office or consult with your local extension agent..