Global Warming in the Garden

We know our gardens are changing, but now it's official.  The National Arbor Day Foundation has adjusted our hardiness zones warm-ward and the official USDA adjustments are in the works.  The result?  "You could say D.C. is the new North Carolina," says the curator of the U.S. Botanic Gardens.   Here's the Washington Post's report.

So now that D.C.'s winters are similar to North Carolina - even to parts of Texas! - what does that mean?  Happier crape myrtles, Southern magnolia, bald cypress, needle palms and yaupon hollies.  And on the Garden Writers Listserv there's this report from landscape designer Jeff Minnich: 

My garden in Arlington, VA, is living proof...and not just living, but thriving:  needle palms, windmill palms, weeping yaupon holly, live oak, gardenias, cast iron plants, fatsia, chindo viburnum...the list goes on.  It looks like South Carolina in my front yard, which is more protected.  My camellias are pushing eight feet, and the biggest chindo viburnum is pushing 20 feet.  Frankly, I love it. 

But we're not just gardeners here, we're eco-gardeners, so let's turn to the down side.  Native plant advocates won't like this, from the WaPo article:  "Native plants might find their growing seasons shifted, their life cycles out of sync with pollinating insects, if warming trends continue to affect them."  The Botanic Garden curator agrees: "It's alarming, when you look at native plant communities."  So with temperatures and CO2 added to the list of things that have changed since the Pilgrims landed, will native plants wind up in plant museums?

And this just in:  Anne Raver, in today's New York Times, lists lots more down sides to climate change:

• Weeds like poison ivy and ragweed are thriving.  With higher temps and increased CO2, ragweed produces 10 times the amount of pollen.
• Likewise, robust invasive plants like English ivy and Japanese honeysuckle are thriving under the changed conditions.
• Canada thistle has become more resistant to herbicides, requiring 3 times the dosage in the presence of higher carbon dioxide.
• There's increased danger of drought and extreme precipitation events (what some are now calling "global weirding").

Sigh.  Well, at least Raver suggests a few things gardeners can do, in our own tiny ways, to combat global warming:

• Stop tilling.  Exposing microbes to air creates more carbon dioxide.
• Use cover crops to slow the release of carbon.
• Limit the use of chemical fertilizers, which are manufactured using fossil fuels.
• Get rid of those leaf blowers and gas-powered lawnmowers.  Here she reminds us that one hour of gas-powered lawn-mowing produces the same pollution as driving 200 miles in a car.  (But what kind of car, Ms. Raver?  If memory serves, the comparison uses a new car with average fuel efficiency.)

And Raver's last suggestion: "If a lawn is too big for a people-powered reel mower, it can be shrunk down by planting ground covers and trees, which will take more carbon dioxide out of the air.  The same principle applies to roofs and terraces: more plants absorb more carbon dioxide."

Hold it - the last time I checked, lawn is a groundcover and Kentucky bluegrass and tall fescue are plants, so I'll assume Raver isn't contributing to the broad-brush lawn-bashing that's become fashionable of late.  She's just showing folks how to get rid of their gas mowers.  (Having switched to electric last summer, I can report enjoying the quiet but concluding pretty quickly that it's worth paying more to lose the cord.)

Here's a related story from Europe, where the plea is "Let it Snow."  Apparently it's not a good time to be in the ski resort biz.

Comments

[JLB]

Interesting and somewhat disturbing news all around - thanks for the links.

I like the list of suggestions for what gardeners can do to help... without summarily bashing lawns, I heartily agree with slowly chomping out lawn sections to decrease the overall area by planting more trees and shrubs.

I am definitely curious to see what the effects of climate change will be on native species. Perhaps they will boldly adapt? Or pull up their roots and migrate?

[Amy T.]

I think Raver's comment is just worded poorly. He makes it sound like "ground cover" will absorb more carbon dioxide than a lawn, but I think he is actually referring to the fact that ground cover would not need to be mowed a gas-guzzling lawn mower.

[Kathy]

Poison ivy, a weed? But-but-but it's a native plant.

[Gloria]

It is more complicated than just planting. Turf is cut weekly and then it releases the CO2 back into the atmosphere as it rapidly degrades.
Native plants or groundcovers with deep roots can create a carbon sink. Read the following EPA link.
And don't discount it because it does not fit your landscape plan. Do what you wish in your own space but educate yourself to really know what you reap.A lawn is not evil but it is less effective if you have environmental concerns.
http://www.epa.gov/greenacres/toolkit/chap2.html

Natural vegetation can help to combat global climate change (the "greenhouse effect") by removing carbon dioxide (CO2) from the atmosphere. Plants remove CO2 from the atmosphere and store the carbon in the body of the plant, the root system and the soil.

[M Sinclair Stevens (Texas)]

So how much like Texas will D.C. have to get before it's too warm to grow tulips, most daffodils, and any fruit tree (like apples and pears) that require a cold period? When will the lilacs go?

[ginger]

Gee, the earth is 4.5 billion years old and temperature record keeping has been going on for...how many years? Maybe two hundred! Barely a blip in the scheme of life. Ahh but it is all about human life isn't it!

[The County Clerk]

Ginger - your argument is, of course, completely valid. The earth WILL be fine. It IS a blip. No question. It will correct.

It might be a statstical anomaly or it might be fossils fuels. Doesn't really matter. We know the fossils fuels contribute if not cause.

The only trouble I see with the argument stems from the fact that I, as a human, have no other place to live at the moment... and my survival band is surprisingly narrow. I hope this "blip" doesn't turn my species into a blip.

Besides, I've planted a bunch of slow growing plants. I want to be around to see the flowers.

(By the way, excellent post Susan.)

[The County Clerk]

You know... I navigated away and did some other things and found myself getting upset.

I'm sorry, but the whole "we don't have enough data out of 4.5 billion years" is just ridiculous.

We need more data. But we have LOTS of data.

For example, take a look at what we know about Little Ice Age. We know about the Medieval Warm Period. We know that 8200 years ago we dipped down into a roughly three century chill.

We know all kinds of things.

I don't know if the globe is warming permanently or not. I don't know if it is natural or caused by us. I'm not a scientist or an activist.

But I do know that we live small temperature band. I also know that when things change a little, for whatever reason, crops fail and disease floursishes. It get's unfun. Cultures fail. Societies fail. Maybe we'll survive. Maybe we won't. But change like this sucks.

And we know that there are things we do which contribute carbon to the atmophere.

With or without a 4.5 billion databank, it is pretty clear that we should minimize those things huh?

I mean... right?

*whew* I feel better

http://en.wikipedia.org/wiki/Little_Ice_Age

http://en.wikipedia.org/wiki/Medieval

http://www.serendipit-e.com/blog/2006/01/broken_ice_dam_.html

[Ki]

I wonder where the often quoted "...care driven 200 miles..." information came from? Lots of writers have thrown it out not checking the source to see if it's valid or correct. They also lump all small gas engines in the same category. The two stroke engines, the ones where you have to mix oil with the gas is probably what they are talking about when they quote the "200 miles"..., is quite a polluter but now usually used only in small cheap string trimmers, chain saws, leaf blowers, hedge trimmers etc. Most of the lawn mowers use 4 stroke engines which are way less polluting. Still not good but much better than before. I too tried using a corded electric mower but it was an act of frustration especially when we have a lot of shrubs and trees to go around. Quiet and efficient but the cord got tangled and it wasn't powerful enough to go through tall grass. My guess is that the ones with a battery would be even less powerful.

Because of the larger surface area of trees and shrubs compared to a shorter lawn, getting rid of the grass is probably minimally better for the environment. We are slowly digging out the lawn as we make more planting berms. We are the black sheep of the neighborhood as they all have large sweeping expanses of lawn with minimal other plantings mostly around the house.

Hey I now live in zone 7. More plants to buy, like gardenia. Thanks for the interesting article.

[susan harris]

Clerk - so glad you surfed back here to vent - I mean rant. And I agree.
Gloria, since you directed me to "educate yourself to really know what you reap," I read the EPA article, which is terrific and I only disagree on one point - its persistent heralding of "native" plants as the only plant of choice to achieve all the enviro-benefits. "Native perennial plants are well adapted to local soils and to enviromental conditions such as summer heat and drought." Isn't the point of global warming that enviromental conditions have changed since the Pilgrims and will continue to change? And on developed sites, often the soils aren't remotely native or natural. Then there's all the nonnative diseases we now have to contend with, plus competition from imported plants, the overpopulation of deer - the list goes on.
So how about we get real and start recommending plants that DO THE JOB, whatever their origin, because we're asking a very small group of plants to accomplish a helluva lot these days. And BTW, the "prairie grasslands" the EPA recommends? Well, they're native to the prairies but not the rest of the country, like the naturally forested East Coast.
Oh, one more nit to pick about the EPA article: its assertion that lawns are chemically dependent - only if they're grown that way. Let's debunk the notion that lawn HAS to be grown conventionally.

[Gloria]

Sorry about that Susan. You know how those native plant enthusiasts are.Sorta meant 'in general' gardeners should look into what is known rather than opinions about what is known. Then make your own decisions about your priorities.
As for native plants(This is opinion)there are no more rules than with other plants. Fitting a native to its environment is more important than where it was discovered.Plants can and do travel to new locations albeit rather more slowly than is convenient for human use.
As a group most north american natives have not had natures needs bred out of them. They have not yet been altered to flower bigger and longer and brighter to suit a 'please the gardener to sell more' priority.
So there are choices for the bees and butterflies, for the dry shady spot under the trees and the sometimes soggy place.
Natives tend to thrive in communities that need a similar environment then assist one another and work well with the wildlife.
I find that North American natives more often fit my intended purpose more efficiently.