Marin Master Gardeners
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Marin Master Gardeners

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Increasing biodiversity in our gardens will help offset harmful human impacts

September 3, 2011
Dave Phelps

WE'VE ALL HEARD about the dramatic loss in biodiversity in forest, aquatic and other ecosystems. But did you know that more than 70 percent of biologists recognize this current period as the ongoing Holocene Extinction Event? We are in a period of mass extinction thanks to human impact, also referred to as the anthropogenic extinction.

In 1983, a basic computer simulation by James Lovelock and Andrew Watson proved that a theoretical Earth-Sun system could regulate its temperature with two species of daisies — white daisies, which reflect light, and black daisies, which absorb light. Called Daisy- world, this simulation and more complex simulations that followed showed that increased biological diversity increases ecosystem stability and helps protect against disruptions such as those caused by temperature extremes or human activities.

Ecologists Felicia Keesign and Drew Harvell of Bard and Cornell universities have shown that as biodiversity diminishes, the species most likely to go extinct are those that could best protect against infectious disease. Because of climate change, there is great concern over anticipated health risks as well as access to fresh water and food resources. A key component is agricultural biodiversity, which is directly related to our nutrition and health. Insect pollination, soil fertility, and water and atmospheric regulation are compromised by a reduced biodiversity.

How can we transition from being part of the problem to being part of the solution? Besides technological growth, increased community structure complexity, managing population and protecting natural resources, we can increase our agricultural ecological biodiversity. Increasing the genetic diversity of the plants we grow can help protect our food supply. Wherever monoculture is practiced and genetic diversity is limited, disease follows, as pathogenic organisms adapt to take advantage of the dominant or only cultivar.

Unfortunately, our agricultural industry is going in the wrong direction and may be harming our food. Industrial agriculture favors a genetic uniformity that promotes the use of commercial varieties and genetically modified organisms (GMOs). These monocultures dramatically reduce diversity and can cause what is called genetic erosion — the loss of individual and complex genes that help protect food crops from pathogens and take advantage of habitat extremes and changes. They also adversely affect the diversity and effectiveness of pollinators and soil organisms. Monocultures are often highly dependent on synthetic fertilizers and pesticides, which further threaten the functional agroecology.

Fortunately, community and global awareness is growing and positive changes are being made through politics, our purchasing decisions and what we choose to grow at home. For food crops, look to heirlooms or open pollinated crops. Whether you are intrigued by the vast array of colors, shapes and tastes; the historical importance; or perhaps just interested in preserving genetic food crop diversity for future generations, heirlooms are rewarding to grow. There are a growing number of laws, seed banks and nurseries that now grow and protect these valuable plants. You can learn more at the Heirloom Exposition in Santa Rosa from Sept. 13 through 15; it will feature more than 250 vendors and farm producers, educational sessions and tastings of hundreds of heirloom varieties.

We can also blend climate-appropriate plant communities to boost biodiversity in our gardens. That can include water, shelter and forage elements for wildlife habitats so a wider range of insects and vertebrates can thrive. Compost, mulch and cover crops help reduce erosion and conserve water while promoting a biologically diverse soil ecosystem for nutrient cycling, water purification, and improved soil structure and fertility. Reducing or eliminating synthetic fertilizers and pesticides also promotes increased biodiversity through a reduction in pollution as well as reducing unintentional death to beneficial insects and animals. And we can avoid planting invasive plants.

By increasing our ecoliteracy and taking an active part in increasing the biodiversity of our food crops and gardens, we are helping to offset the harm our species is causing on Earth. It will also help stem mass extinction while helping to protect our food supply and our health.

We have the ability and responsibility to create dramatic and lasting change for our future and that of countless other species.

The University of California Marin Master Gardeners are sponsored by UC Cooperative Extension. For questions about gardening, plant pests or diseases, call 499-4204 from 9 a.m. to noon, and 1 to 4 p.m. weekdays, or bring in samples or pictures to 1682 Novato Blvd., Suite 150B, Novato.

IF YOU GO

What: National Heirloom Exposition
Where: Sonoma County Fairgrounds, 1350 Bennett Valley Road, Santa Rosa
When: Sept. 13, 14 and 15 
Cost: $10 to $25; free, children 17 and younger
Information: 707-509-5171 www.heirloom expo.com

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