Thursday, June 23, 2016

Why Plant Local Natives?

All photos show local native plants and critters on our land.
Here, Clarkia rubicunda in a protected area has been reseeding for several years

I'm writing this post for a lovely person I met recently, an aesthetic pruner and lover of California natives and natural gardening, who requested it.

UPDATE 7/2/16: I just read a post on Beautiful Native Plants called The Science Behind our Commitment to Native Plants and it is worth your while to read it too. It backs up with scientific studies the points that Tallamy makes regarding native plants supporting more insect food for insectivores like birds than non-native plants - studies comparing two similar gardens, one mostly natives and the other not - and etc. Read it - it's good stuff!

Why plant local natives is a topic I've been tussling with for some time and if I waited for the tussle to be over, I'd never complete the post! 

For me - the joy of experiencing and working within a semi-intact ecosystem (or three in my case) where I live is one of the main reasons. Also keeping the native gene pool free from genes they would not encounter in the normal course of evolution (though on this a little more later.) For gardeners living in suburbs - there are other reasons.

lupin with spiderwebbing. I think it's the l lavender form of Lupinus arboreus

A little green sweat bee!

First let's find a useable definition of a native: 

A plant or animal that has evolved in a given place over a period of time sufficient to develop complex and essential relationships with the physical environment and other organisms in a given ecological community. (My emphases.)
Definition taken from The Living Landscape: Designing for Beauty and Biodiversity in the Home Garden by Rick Darke and Douglas Tallamy.

Monardella villosa and Eriophyllum confertiflorum - coyote mint and golden yarrow

I've divided this post into five tidy little sections - and here they are.

Basic section:  Why plant local natives? Most insects evolved to need local native plants to breed on. And birds need those insects and their larvae to feed their babies.

Chalcedon Checkerspot on seaside daisy, Erigeron glaucus - which is local to our coast in Santa Cruz though not my ecosystems. Used as an ornamental and good nectar plant.

Crysalis of Chalcedon Checkerspot on local monkey flower, Mimulus aurantiacus

Douglas Tallamy is an entomologist. He's raising a movement among gardeners to build corridors of native plant gardens that will link the tiny fragments of natural land that remain "undeveloped." And only about 5% of land in the USA falls into that category. On his Bringing Nature Home web site, he says:
Our studies have shown that even modest increases in the native plant cover on suburban properties significantly increases the number and species of breeding birds, including birds of conservation concern. As gardeners and stewards of our land, we have never been so empowered to help save biodiversity from extinction, and the need to do so has never been so great. All we need to do is plant native plants!
Tallamy doesn't say local here - but in the body of his work he does stress the necessary connections between organisms in local ecosystems, especially between local native plants and local native insects which require them to breed.

Banana slug!

Tallamy works in Delaware, but while his examples are local, the principles are universal. Wherever you live -- read his book, Bringing Nature Home, and his new book (co-authored with Rick Darke), The Living Landscape.

Be sure to check his Bringing Nature Home web site for a more detailed intro to these ideas.

Pretty Clarkia rubicunda - photo 2. It's just going crazy now where it reseeds in my garden!

Slightly ranting section: Smearing life forms around the globe (or the state) is not evolution and decreases biodiversity!

One thing we humans are increasingly good at is picking up gobs of life forms from here and dumping them over there. We all know about this. It began in a serious way about 500 years ago with sailing ships, and accelerated after internal combustion engines etc turned globe trotting into globe galloping. Plants, animals, pathogens - you name it, we've spread it. Well, almost.

"But we are part of nature, and so this is natural," is a common response to this human activity. "It's all just part of evolution, isn't it?"

No. No, no no. No, I can't accept that, sorry! -- for so many reasons.

Without the natural checks and balances that exist in an organism's evolutionary home, some of these imported life forms spread freely, most especially if they are very far from that home. Those that become invasive smother the million-fold subtle relationships of naturally evolved ecosystems.

To say that all this rapid spreading is OK is (to use an extreme example to make a point) like saying it's OK to spray orange and yellow paint all over the Mona Lisa and call it a neo-Rothko: It's different but it's still good, right? Like novel ecosystems. Cos Rothko is great too, right? Oh - sorry about the Mona Lisa, though.

To me, this is a novel ecosystem -- composed of local natives some of which
(like the paintbrush, Castilleja affinis, I introduced!

Spreading life forms beyond their evolved homes has been demonstrated to reduce biodiversity.  Especially when it comes to insects. (For some supporting studies see article You Can't Evolve if You're Extinct.)

It's true we have to accept the trashed up and unmanaged areas that are now called "novel ecosystems." There's no going back, not on a large scale. But I'm still not about to celebrate it or use it as an excuse to do questionable things to the environment. (For more on this see novel ecosystems are a trojan horse for conservation -- the very term is 'novel ecosystem' is ill-defined and unsupported by examples).

Fence lizard at home

Towhee, I think, munching on native needle grass - Stipa cernua, nodding needle grass.

Like many, I'm sighing and trying to find resignation as I read about people valiantly making lemonade out of this inevitable "new normal" and its potential for perhaps providing ecosystem services -- to us humans, if not to the former ecosystem inhabitants!

Pearly everlasting

Madia elegans

Now, I know that 10 to 40 thousand years ago, wherever humans migrated to, megafauna disappeared in fairly short order, and this had a huge impact on ecosystems. Did you know that? It's not that we slaughtered them like Buffalo Bill, hundreds per day or wiped them out for fun like Passenger Pigeons. We just steadily ate them faster than they could reproduce. That's one compelling theory anyway. Except in Africa, where we all evolved together to start with.

Human interference isn't new. We were the first invasive species, you might say.  But change today is vastly greater and tremendously faster.

I also know that the forces of evolution would eventually do something with "novel ecosystem" messes -- if humans could actually leave things alone for a few thousand years. It takes time to evolve an actual ecosystem - an intricate-at-all-levels network of interdependent organisms and energy flows. But we don't stop interfering, do we.

True there are efforts made. Regulations are perhaps implemented and policed. But are they ever going to be enough?

If I'm wrong, please tell me how - because this is too depressing and I'd like to cheer up.

Another "neo-novel ecosystem" ;-)
composed of local sword fern and sedges and other local natives.

Which is one reason why on my property I'm trying to bring in a bunch of very very local natives that I propagate from local wild seed and then - if I can restrain my human urge to fiddle with things - I'll let them go and see what they do. On most of the property that is. And I'll continue to remove non-natives. It's my local refugio for local lovelies. It cheers me up.

The inevitable global warming section.

But what about planting Southern natives in the gardens of Northern California, where they will thrive as the earth warms and local natives frizzle and fry due to climate change?

So what if those Southern natives hybridize with local natives and / or escape from horticulture into the wild? Is that a good or a bad thing?

I tend to think it's bad - and that it would be better for plants in the wild to drift north under their own steam in response to climate change. After all, plants have drifted north and south and gone extinct for many ice ages now, moving and evolving at that - er - glacial pace.

Local bee on Eriophyllum confertiflorum, golden yarrow

Southern Alligator Lizard!!

Burbling Bushtits - gotta add water to that bath!

But global warming is happening so much more rapidly than any previous climate change. It's unprecedented. So how do we know what's right? This question is further explored in the article As World Warms, How Do We Decide When a Plant is Native? published in Environment 360, a publication of the Yale School of Forestry and Environmental Studies. Interestingly for us literature buffs, the spark for the essay came from a tree that escaped from Emily Dickinson's garden.

A section about some naysayers.

Tallamy and his scientific ilk have their naysayers, such as those who write on websites like Death of  Million Trees (e.g., see post: Do insects prefer native plants? ) and Save Mount Sutro Forest. They're where to go if you're a native plant lover and want to see yourself recast as a "nativist Nazi."

While it's fun to visit these web sites to play Spot the Logical Fallacy games (including Count the Strawmen), it can also be salutary to read them for content. Not all posts are vituperative. They have some points to make. Non native trees can indeed support a lot of wildlife and can be beautiful and harmless.

(And of course -- there IS no mythological fixed state back to which conservationists are trying to pin ecosystems, despite what Million Trees website folk say.)

Be sure to check sources, though, before you buy any ideas. Compare them with those of Douglas Tallamy and other science-based writers, and judge for yourself which are more trustworthy.

Another salutary use for these naysayer sites: it's much easier to notice how passion can distort other people's thinking. But having noticed, check yourself for symptoms. Not always fun, I can tell you from experience, but good for you.

Nice positive closing section with some practical value: Plants from the same community share the same mycorrhizal fungi. So plant them together!

Deer-nibbled ocean spray, Holodiscus discolor - with golden yarrow, Eriophyllum confertiflorum

The Las Pilitas Nursery's page on California native plant communities and companion plantings states that Mycorrhizal associations are the foundations of the plant community:
Most California native plants, their roots, their fungi (mycorrhizae), ... and other associated microorganisms are interlinked and support each other, sometimes for vast areas. ... This interconnection can extend across a whole plant community, even if that community runs for 200 miles.
The Las Pilitas Nursery page says that different plant communities have different fungal relationships - so that if you put, say a riparian habitat plant in a chamise chaparral habitat garden the seedling is unlikely to thrive even if the shade and watering are adequate. Instead:
Plant the plant within the right plant community as we've described, and the fungal community will also be stable. This fungal-plant intermix spreads the stresses of individual plants among the other plants of the community. The seedlings are supported by the larger well-established plants of the community, as long as the community is intact and the young seedlings match the community.
Cool! So at least create blocks in your garden where all the plants come from the same plant community. Probably will work better if you choose plants from communities that would have been on your garden before it was developed - since there might be some local mycorhizzae in the soil - maybe. Or from some soil you could get from nearby. It doesn't take much to inoculate a garden - a handful or two.

Toyon - Heteromeles arbutifolia

Monkeyflower, Mimulus aurantiacus

I am lucky -- I live at conjunction of three active ecosystems: Chamise chaparral, mixed evergreen forest, and redwood forest. I have lots to work with while staying very local. But I also mix things up a little as we get closer to our house. 

You could for fun try to establish plant communities from remoter regions, like a Channel Islands garden for example -- and that might work - not sure about the specific types of fungus though, if it would be present in your soil or if you could get an inoculant would it survive? 

Now what are these guys called again???

Jerusalem cricket in the evergreen forest leaf litter

I suspect a native-but-not-local section of garden would serve your California ecology better than a Mediterranean-but-not-Californian one. And that a Mediterranean-but-not-Californian one would serve wildlife better than most plants from a wet-summer climate like popular garden plants that originate in China or Europe.

As Tallamy says - even if just a part of a garden is devoted to local natives - the benefit to wildlife is tremendous. There's reason enough to plant local!

Pretty Clarkia rubicunda - a last look!


Diana Studer said...

that about local fungi on the roots - perhaps explains why proteas and ericas, our fynbos plants - can be really tricky to grow in a garden. Just quietly turn brown, and fade away, sadly.

Country Mouse said...

Interesting, possibility, Diana - all the interrelationships between plants mediated by the fungus or chemicals in the air etc that we're learning about these days. Totally fascinating.

Katie (Nature ID) said...

Thanks for this thoughtful post. My irk is when folks sell "native" plants, that may have been collected here, exported to the UK or elsewhere (even a couple hundred miles up and down CA), bred with who knows what, then returned here in marketing/PR packages, e.g. the now-common CA garden poppy and blue bush lupine that the City of Monterey wholeheartedly spread around a couple years ago - the plants look nothing like the natives and I suspect they have a completely different genetics that won't work w/ native insects. This year, I've also seen hybrids of the rare local Clarkia in gardens around town. Ugh. I believe, in our efforts to help, we're actually do much more damage to the survival of real, local, native ecosystems.

Country Mouse said...

Hi Katie, and thanks in turn for your thoughtful comment. Horticultural use of natives bothers me too. Tallamy notwithstanding - for the reasons you mention. For wildlife value in suburbs I think cultivars etc are OK, but where natural populations are nearby it's a problem. I used to proselytize locally - now I don't. I'm happy when my neighbors have Australian plants around their house because they 're at least not bringing in non-local natives that might hybridize with the locals. I may be overly puritanical about that. When I bring in a native I check that it won't do that. I've removed some mistakes made earlier in my time here. There hasn't been enough study done on what plants will or won't hybridize, so we're working without hard data. I love your site and hour thoughtful posts!