By Susan Lewitt.
Biodiversity impacts us in endless ways. It affects our health, our food, the natural beauty seen around us, air, water, soil, and environmental resilience. “A wide range of wildlife makes agriculture possible, including bats, bees, birds, dragonflies, frogs, ladybugs… among countless others… bees alone boost U.S. crop revenue by more than $15 billion per year. Worldwide, bats save corn farmers about $1 billion annually by eating pests like corn earworm larvae… Biodiversity is linked to human health in several ways. By having a diverse mix of plants, fungi, and animals to eat, we ensure nutrition that buffers our bodies against … hardships. Higher biodiversity has also been linked to lower instance of disease … around protected natural areas.” (https://www.mnn.com/earth-matters/wilderness-resources/blogs/why-biodiversity-big-deal)
Native plants are plants growing in their natural dispersal range.
Nonnative plants are plants growing beyond their typical range including feral and hybrid species.
Invasive species are those occurring in areas where they normally don’t occur, displacing natives, changing invaded communities, possibly forming monocultures.
(For complete definitions see Invasive Plants of California’s Wildlands, edited by Carla Bossard, John M. Randall, Marc C. Hoshovsky)
Restoration involves removing invasive and exotic plants and allowing the original native plants to grow back from existing seed banks or planting replacements of species naturally found there.
Exotic or nonnative plants are problems because many need fertilizers, pesticides, and usually more water than natives. They also can become invasive, especially Mediterranean climate plants. Exotics may overtake, invade, form monocultures and don’t support the native fauna. This decreases biodiversity. If they are easy to grow and give you lots of volunteers, they can spread into nearby natural areas by means such as birds, other animals, wind, or runners.
Native plants support and contribute to biodiversity. They are adapted to our soils, need less water, and usually don’t need soil amendments. They also support each other through their root wide web system. According to Calscape (https://www.calscape.org/) there are 737 native San Diego plants suitable for landscaping that help you support biodiversity. Categories include shade, sun, trees, shrubs annuals, ‘very easy’ to grow plants and more. To support biodiversity in your own neighborhood, look up Calscape and enter your zip code to find out the best native plants to grow for your area. These plants sustain and attract native pollinators and other fauna, bringing you more native birds, butterflies, and bees. Over 700 San Diego native bee species, including many solitary nonstinging bees, are supported by the numerous incredible native San Diego plants.
In future articles I will explain the problems caused by specific invasive plants that have been used in landscaping and what to use instead to support our local biodiversity. An example of an invasive species, Salt Cedar (Tamarix chinensis) will make soil very salty and unfavorable to native plants.
Everything we do everything we see; it’s all complexly interconnected. As we change things in our environment, it affects us in ways that we cannot predict. If something happens that wipes out one species in a highly biologically diverse system, there will likely be other species to fill its temporarily vacant niche and little will change. As ecosystems become less biologically diverse, there may not be replacements for lost species, and it is more likely to become unbalanced or even collapse when additional species are lost, causing problems within the system and for humans.
Due to COVID-19, the 2020 CNPS Native Garden Tour in the East County, with its beautiful gardens and talented artists has been postponed. Join us in April 2021 to see how well natives can enhance your landscapes and attract birds, pollinators, and other native animals.
Susan Lewitt has lived in San Diego since 2001, originally from
New York where she studied art and botany. She is a member
of CNPS and a volunteer for the zoo. She has participated in projects and events that involve restoration, invasive weed removal,
educating people about and installing native gardens, including
workshops and garden tours. She is also an artist who enjoys drawing butterflies and thinks that doing everything we can to help the environment is important to our health and the health of our world.
To that end, Susan adheres to a "reduce, reuse, & recycle" lifestyle, eating organic, Non-GMO and plant based meals as much as possible and then writes about much of it for the Clairemont Times.