Re:You Can Turn Your Backyard into a Biodiversity Hotspot
by crvrd on Monday February 27, 2023 @04:49PM
(#34962369)
This past year I quit my tech job to start a native plant nursery. I see some commenters here who are skeptical of the value of native plants, so I would like to make a few small points.
1: It is sometimes argued that native bird and insect species will adapt to use exotic plants. This is true for some species - for instance, bumble bees tend to adapt well to exotic nectar sources. Robins will eat exotic berries. Species like this are often called "generalists". However, there are also "specialist" species, which need specific types of plants, for food, shelter or some other purpose. They do not adapt to exotic species well. I will give some examples that come to mind (I am in Seattle, so examples may be biased to the PNW):
- Butterflies often have specific host plants which they lay their eggs on. The most famous relationship is Monarchs butterflies and Milkweed plants. Near Seattle we also have Taylor's Checkerspot butterflies and Harsh Paintbrush (with maybe a couple other plants). Fender's Blue butterfly and Kinkaid's Lupine. Karner Blue butterfly and Sundial Lupine. All of these butterflies (and a few of the plants) are endangered. Many other butterfly species need specific plants to lay their eggs.
- Many bee species collect nectar from specific flowers, and do not adapt well to other flowers. One example is Diadasia Nigrifrons, which is a specialist pollinator of Checkermallow flowers. (Many species of Checkermallow are also endangered.)
- Many bee species - called cuckoo bees - are kleptoparasitic, and they need specific other bee species. For instance, Suckley's Cuckoo Bumble Bee is dependent on the Western Bumble Bee. These species are both extremely endangered, largely due to the spread of bumble bee disease from Europe.
- Many bird species subsist largely on seeds from specific plants. One famous example is the relationship between Clark's Nutcracker and the Whitebark Pine. Whitebark Pine is now struggling, largely due to the introduction of White Pine Blister Rust from Europe.
- For some good data on how native bees use exotic plants, see the research from the Oregon State Garden Ecology Lab. It appears that European honey bees largely use exotic plants, and native bees largely use native plants. https://blogs.oregonstate.edu/gardenecologylab/2019/11/04/20...
There are too many specialist interactions to count, and we do not even have knowledge of all the species that live near us. Ecosystems are complex systems, and we cannot assume that they will adapt to exotic species.
2: People sometimes draw parallels between exotic plants and immigration, implying that it is nationalist or bigoted to promote native plants. However, plants are not humans. They cannot immigrate by themselves, but they can be spread by humans. Indigenous people have lived all over the world for millennia, and have stewarded native ecosystems. I would argue that native plants do not represent nationalism - rather, exotic plants represent imperialism.
3: Plant interactions are more complex than people often give them credit for. They do not simply take up space in one's garden, they also interact under the soil. Many species of plants are allelopathic, meaning that they can exude chemicals which are poisonous to other species. Many plants are allelopathic to one degree or another, and plants evolve to be resistant to others' allelopathy. A couple examples (not all plants are as damaging as these, but many can be damaging to one degree or another):
- Common Burdock is a European plant which is allelopathic. Other European plants have adapted to it, but North American plants do not have the same adaptations. So when it establishes here, it kills native plants. Often Burdock is seen with no native plants near it, but with other exotic European plants growing there.
- Scotch Broom is an incredibly invasive legume which is allelopathic. It is one of the primary threats to grasslands and prairies in our area. Once it is established, it will damage mycorrhizal networks, killing other plants.
4: One of the benefits of native plants is that they are adapted to your region, and can be "easy" to grow. Some people will respond to this with examples of exotic plants that are adapted to similar regions, and grow well too. I would exercise caution here, because these are plants that either are invasive, or will likely be listed as invasive - and you may not be able to see their invasive behavior. For example:
- Cherry Laurel grows well here. It is currently not listed as invasive, but I expect it will be soon. It is planted all over the place. Will you notice when birds spread its seed to a forest a mile away? You may prune it religiously, but will the next owner?
- Black Locust is listed as invasive, but it is still commonly sold. How will you prevent birds spreading its seed?
It is easy to forget that our yards are part of the natural environment. But they are, and there are more yards every year. Is your yard an example of habitat destruction, or is it an example of stewardship?
1: It is sometimes argued that native bird and insect species will adapt to use exotic plants. This is true for some species - for instance, bumble bees tend to adapt well to exotic nectar sources. Robins will eat exotic berries. Species like this are often called "generalists". However, there are also "specialist" species, which need specific types of plants, for food, shelter or some other purpose. They do not adapt to exotic species well. I will give some examples that come to mind (I am in Seattle, so examples may be biased to the PNW): - Butterflies often have specific host plants which they lay their eggs on. The most famous relationship is Monarchs butterflies and Milkweed plants. Near Seattle we also have Taylor's Checkerspot butterflies and Harsh Paintbrush (with maybe a couple other plants). Fender's Blue butterfly and Kinkaid's Lupine. Karner Blue butterfly and Sundial Lupine. All of these butterflies (and a few of the plants) are endangered. Many other butterfly species need specific plants to lay their eggs. - Many bee species collect nectar from specific flowers, and do not adapt well to other flowers. One example is Diadasia Nigrifrons, which is a specialist pollinator of Checkermallow flowers. (Many species of Checkermallow are also endangered.) - Many bee species - called cuckoo bees - are kleptoparasitic, and they need specific other bee species. For instance, Suckley's Cuckoo Bumble Bee is dependent on the Western Bumble Bee. These species are both extremely endangered, largely due to the spread of bumble bee disease from Europe. - Many bird species subsist largely on seeds from specific plants. One famous example is the relationship between Clark's Nutcracker and the Whitebark Pine. Whitebark Pine is now struggling, largely due to the introduction of White Pine Blister Rust from Europe. - For some good data on how native bees use exotic plants, see the research from the Oregon State Garden Ecology Lab. It appears that European honey bees largely use exotic plants, and native bees largely use native plants. https://blogs.oregonstate.edu/gardenecologylab/2019/11/04/20...
There are too many specialist interactions to count, and we do not even have knowledge of all the species that live near us. Ecosystems are complex systems, and we cannot assume that they will adapt to exotic species.
2: People sometimes draw parallels between exotic plants and immigration, implying that it is nationalist or bigoted to promote native plants. However, plants are not humans. They cannot immigrate by themselves, but they can be spread by humans. Indigenous people have lived all over the world for millennia, and have stewarded native ecosystems. I would argue that native plants do not represent nationalism - rather, exotic plants represent imperialism.
3: Plant interactions are more complex than people often give them credit for. They do not simply take up space in one's garden, they also interact under the soil. Many species of plants are allelopathic, meaning that they can exude chemicals which are poisonous to other species. Many plants are allelopathic to one degree or another, and plants evolve to be resistant to others' allelopathy. A couple examples (not all plants are as damaging as these, but many can be damaging to one degree or another): - Common Burdock is a European plant which is allelopathic. Other European plants have adapted to it, but North American plants do not have the same adaptations. So when it establishes here, it kills native plants. Often Burdock is seen with no native plants near it, but with other exotic European plants growing there. - Scotch Broom is an incredibly invasive legume which is allelopathic. It is one of the primary threats to grasslands and prairies in our area. Once it is established, it will damage mycorrhizal networks, killing other plants.
4: One of the benefits of native plants is that they are adapted to your region, and can be "easy" to grow. Some people will respond to this with examples of exotic plants that are adapted to similar regions, and grow well too. I would exercise caution here, because these are plants that either are invasive, or will likely be listed as invasive - and you may not be able to see their invasive behavior. For example: - Cherry Laurel grows well here. It is currently not listed as invasive, but I expect it will be soon. It is planted all over the place. Will you notice when birds spread its seed to a forest a mile away? You may prune it religiously, but will the next owner? - Black Locust is listed as invasive, but it is still commonly sold. How will you prevent birds spreading its seed?
It is easy to forget that our yards are part of the natural environment. But they are, and there are more yards every year. Is your yard an example of habitat destruction, or is it an example of stewardship?