Author: Bert Cregg

Another W.O.W.

We’ve been beating up nurseries over Why-Oh-Why (W.O.W) do they sell things like Scot broom.  Here’s one of my  favorite W.O.W’s from the landscape side (Homeowner division).

Why-oh-Why do people think grass clippings make a good mulch?!  This photo comes from near my home.  The homeowner put the clippings down about two months ago.  All the trees were dark green and healthy before the clippings were put down.  Note how chlorotic the trees in the middle have already become and the dead lower limbs where the trunks were covered.   We’re all for mulch but this ain’t it!

Volunteering for duty

One of the advantages of having a couple acres (and not being especially fastidious about weeding) is that sometimes you get your landscape plants for free.  I always keep an eye out for interesting plants that may turn up on their own – or a least get left behind by our bird friends.  Here are some volunteers that have shown up recently at Daisy Hill farm that I’ll work into the landscape.

 


Sassafras (Sassafras albidum) are notoriously difficult to transplant.  I’ll leave these sassafras volunteers where there are and relocate the shrubs in the bed.  I’m looking forward to some awesome fall color in a few years.

 


The native range of redbud (Cercis canadensis) only extends into the southernmost counties of Michigan but they generally do fine here in the Lansing area (just north of the end of the native range).   We have an old redbud in the front of our house so we get volunteers from time to time.  This one is on the edge of our patio so it’s easy to keep an eye on.  I’ll let it grow on another year or so and then find it home.

 


Most people probably wouldn’t get too excited about eastern redcedars (Juniperus virginiana) showing up on their own.   When I was with the US Forest Service, my grad student and I did research on seed germination of eastern redcedar and Rocky mountain juniper (J. scopulorum).  Ironically they can be difficult to grow as seedlings in nurseries because the seed are doubly dormant (they have a tough seed coat that requires scarification and the embryo is dormant and requires cold stratification).  I’m planting conifers as a screen on the south side of property. I’ll move these guys and a couple of their friends in the spring.

Confessions of a carbon sequestration skeptic

One of the potential environmental benefits that came up in our discussion of the pro’s and con’s of turfgrass was carbon sequestration.  The basic premise of carbon sequestration is to take CO2 out of the atmosphere and ‘lock it up’ in a form that won’t contribute to further global warming.  One of the fallacies floating around these days is that any plant that photosynthesizes, takes up CO2 and thereby sequesters carbon.  What we need to realize is that leaves give off CO2 at night via respiration and all non-photosynthetic (non-green) plant parts such as roots and stems give off CO2 virtually all the time.  Turfgrass has some potential to sequester carbon, primarily as soil C. If we consider that a 7” deep layer of soil weighs 2 million pounds, increasing soil carbon by 1% can sequester 20,000 lbs of C per acre.  How long does it take turfgrass to increase soil C by 1%?  Don’t know, but I’m sure it takes awhile.  Also, there is a limit to amount of carbon a give soil can store as C is respired away by microbial activity so eventually a steady state will be reached.  (Plus we haven’t even subtracted out fossil fuel carbon to maintain turf).  Some plants, such as trees, do have the capacity to sequester carbon in wood for long periods – think redwoods, sequoias and redcedars.  But these trees cover only a small fraction of the world land area.  Intensively managed forestry plantations can take large amounts of carbon out of the atmosphere and sequester it into wood.  The question then becomes what do you do with the wood?  If we burn it for biomass energy; Foof! All that C is right back in the atmosphere.  Still better than burning fossil fuels but also a little less than carbon neutral at best.  We can build houses with the wood from the plantation – the carbon will be sequestered as long as the house lasts.  My home and barn were built in the 1890’s so the carbon taken out of the atmosphere by those trees is still locked up.  If we really want to get serious about carbon sequestration, however, our best strategy would be to convert the entire Upper Peninsula of Michigan to fast growing poplar plantations, harvest the wood every 15 years, and sink the logs in Lake Superior where the cold water will prevent decay.  Sound funny?  I’m not the only person thinking this way.  See Strand and Bedford 2009. Ocean Sequestration of Crop Residue Carbon: Recycling Fossil Fuel Carbon Back to Deep Sediments Environ. Sci. Technol., 2009, 43 (4), pp 1000–1007. http://pubs.acs.org/doi/abs/10.1021/es8015556  

 

Bottom line: carbon sequestration is a very complex process and sequestering carbon for more than a few decades takes more creativity and brain-power than most of us can muster.  However, trees and landscape plants do have important role to play in mitigating climate change and it doesn’t require heroic feats of engineering.  Trees and landscape plants can effectively cool buildings, thereby reducing air conditioner use and save fossil fuels – see the USDA Forest Service Urban Forestry Research site for a few examples http://www.fs.fed.us/psw/programs/cufr/research/studies.php?TopicID=3   ultimately this is landscape horticulture’s contribution to climate change.  Carbon sequestration?  It’s a drop in a very big bucket.

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Is brown the new green?

An acquaintance of mine (not coincidentally, an irrigation supplier) brought to my attention a recent editorial from USA today by Laura Vanderkam, entitled ‘’Out of Fashion: Green Lawns.” http://www.usatoday.com/news/opinion/forum/2010-08-17-column17_ST_N.htm?loc=interstitialskip#uslPageReturn  The basic premise of the editorial is that we Americans are ruining the environment by maintaining lawns.  Now, to be sure, there is plenty of room for improvement in lawn and landscape maintenance, particularly in terms of water management and pesticide use.  But, for better or worse, Americans love their lawns.  I love my lawn, imperfect though it may be.  We’ve got a couple of big oaks in the backyard and I love to lay a blanket in the shade and read a magazine on Sunday afternoon or just doze with the Tigers game on in the background.  Love to play croquet and bocce.  Love to kick a soccer ball around with my daughter.  In the interest of full disclosure, my lawn will not win any awards.  At this moment about 75% of my lawn is brown, panting in the heat of our first true summer in several years.  I water a small portion of the lawn for the aforementioned croquet/bocce playing, and magazine reading/ Tigers’ game snoozing.  For most part, however, I take a lazzez faire attitude to lawn upkeep; I keep a 3” mower height, apply a little bit of Weed-b-Gone every other year in the section nearest the house when the dandelions are ready to drive me to distraction and, if I remember, put down a half rate of fertilizer in the spring.  Nevertheless I was taken aback by Ms. Vanderkam’s assertion, “Few parents would light a cigarette at a playground anymore, even if it’s not illegal, and we should start treating the presence of a vast, green, cropped grass lawn in the middle of summer the same way: as a weird and antisocial thing.”


Let the games begin. Mrs. Cregg scores again on the opening day of Cornhole season 2010.

Wierd and antisocial? Really. From May to September, our lawn is the most social part of our place.  What’s really needed, and often the hardest to find, is some middle ground.  It’s easy to resent people that belong to homeowners associations that require perfect lawns and hire ‘Chemicals R Us’ to maintain their pristine turf.  However, lawns and landscapes can provide an array of benefits, some tangible like oxygen produciton and cooler air temperature; and some less tangible, like a perfect croquet shot..  We can, and should, look to reduce water and chemical use on lawns.  But Ms. Vanderkam will get me off my John Deere riding mower when she can pry the steering wheel from my cold, dead fingers.

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Need a lift?

One of the topic groupings for our posts is titled ‘Cool research’.  The subject of today’s post has actually been around for a few years but I still think it’s pretty cool.

 

When we think of interactions between plants we usual think of negative interactions such as competition for water and nutrients or maybe allelopathy.  But there are cases where plants can benefit each other.  One of these is a phenomenon known as hydraulic lift.    Hydraulic lift is the passive movement of water from roots into soil layers with lower water potential, while other parts of the root system in moister soil layers, usually at depth, are absorbing water.  In essence, plants will large, deep root systems (usually trees) bring soil water from depth to the surface where it can be used by other plants.  Hydraulic lift has largely been observed in arid and semi-arid ecosystems, though it can occur in wetter systems as well.  For me, the research that went into discovering hydraulic lift is as fascinating as the process itself.

 

One of the key lines of evidence for hydraulic lift comes from studies of stable isotopes.  As you may recall from college or high school chemistry, atoms of each chemical element have a certain number of protons and neutrons, which give it its mass.  A small portion of each element has extra neutrons resulting in a ‘heavy isotope’.  In the case of hydrogen, approximately 1 in 6400 atoms is heavy hydrogen or deuterium (2H).  Interestingly, the amount of 2H in water can vary depending on the source of the water; this ratio is termed an isotopic signature.  By comparing the isotopic signature of ground water and rain water in a given location, researchers can actually tell where certain plants are getting their water.  One of the classic studies in this area was conducted by Todd Dawson at Cornell in the early 1990’s.   Dawson analyzed isotopic signatures of groundwater, rainwater, and water in various plants around sugar maple trees and determined that many herbaceous plants contained a high proportion (up to 60%) of groundwater.  But how do shallow-rooted plants obtain groundwater?  The neighboring maple trees bring it to the surface from ground water as they are hydrating overnight.  An efflux of water from the maple roots results in a localized increase in soil, which can be utilized by other plants: hydraulic lift.

 

How important in hydraulic lift in most landscapes?  Probably not very.  Demonstrating significant hydraulic lift requires the proper hydrology (shallow ground water accessible to trees or shrubs but not smaller plants) and limited rainfall.  But the importance goes deeper (no pun intended!).  Prior to the advent of stable isotope techniques, many would have been dismissive of the concept of hydraulic lift.    Since 1993 over 100 papers have now been published on the subject.  To me, the ultimate value of Dawson’s work and related studies is showing the importance of keeping an open mind and being receptive to new ideas. 

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Restoration ecologists – you need us! Part 2.

Last month Linda posted on the need for horticultural knowledge for those trying to restore native habitats or at least establish native plants. There seems to be a pervasive notion that if we plant natives all we have to do is stick them in the ground and walk away. They’re native, right?  Don’t need irrigation; don’t need fertilizer; all that good jazz.   Well, often there is lot more to it than that.

 


A case in point.  Over the past couple of years I’ve been watching an unintended experiment near the State Capitol grounds in Olympia, WA.   The State opened up a vista so that the south end of Puget Sound and the Olympic Mountains were visible from the Capitol campus. It’s a lovely view.   As part of the development, a switchback trail was established on the steep hillside to connect the Capitol grounds with the park surrounding Capitol Lake below. A great idea.  Along the trial the hillside was planted with an array of native plants such as Oregon grape, salal, alder, and western redcedar.  Another fine idea.  Now comes the problem.  Near as I can tell, there was no plan for maintaining these native plants.  In fairly short order the hillside has become overrun with grasses, dandelions, and Himalayan blackberries – not exactly the desired effect.  And therein lies the rub.  Everyone is on board to plant natives but who’s on board for the hard work to maintain them.  Keeping weedy species from this planting by hand would take an army volunteers.  Burning is likely out due to the proximity of the Capitol and probably wouldn’t promote the desired species.  The answer?  Most likely a combination of hand-weeding and herbicides.  It is interesting that when the end justifies the means, herbicide is not such a dirty word anymore.  So there you go.   In order to effectively establish and maintain native plants, not only do we need to know about Mahonia aquifolium, Gaultheria shallon, and Alnus rubra; but it also helps to know about glyphosate, flumioxazin, and triclopyr.

Icky Friday puzzle solved


OK, now we know why we usually leave the puzzles to Linda: mine are too easy!  As several folks correctly noted the photo in my yard was an example of the "dog vomit fungus" or, more correctly "dog vomit slime mold" Fuligo septica.  Either way, it’s fairly disgusting and fairly common.  My expereince has been it that it often shows up shortly after I lay dowm some fresh mulch (ground pine bark in this case) and then we get rain and warm temps.  Although sometimes it shows up when I give our dogs too many treats… Hmmm…

Thanks to all those who chimed in with comments and links.  Here’s one more link with some interesting tidbits.
http://botit.botany.wisc.edu/toms_fungi/june99.html

Friday quiz: The case of the bumpy maples

 

OK, this Friday’s quiz is the real deal: everyone gets to play “Extension Specialist for a Day”.  I am stumped on this and so are my colleagues here at MSU.  I used to work for a guy who liked to say, “None of us is as smart as all of us”.  Let’s put it to the test.

The photos below come from a nursery here in Michigan.  The trees are container-grown Red sunset maples.  Pretty routine crop around here.  The trees look fine: good color, full crowns, growing well.  The only problem is that nearly all of the trees have bumps along the bottom 8” or so of the trunks.  The grower is concerned, and rightly so, about consumer acceptance of the trees.  The trees have been examined by a highly qualified pathologist – no evidence of fungal disease; and by a highly qualified entomologist – no evidence of insect activity.   The grower is sitting on several hundred of these trees.  What should I tell him?


NOTE: The name of the nursery is confidential – they just used the calipers from Schumacher’s in the photo.

The importance of knowing your plants

One of the first courses a horticulture student takes is plant materials, or, in the case of a forestry student, dendrology.  Why?  Pretty simple; it’s hard to select plants if you don’t know what they are and what they’ll do in the landscape. Of course, the classic example is a large tree or shrub planted in a tight spot that eventually devours an entire house.  But we usually don’t have to look too far to find situations where a homeowner or landscaper clearly had no idea what plant he or she was dealing with.  To wit, a couple of recent examples of poor plant choices (maybe this can be our next series after “Why do nurseries still grow THAT?”)

I spotted the first example wandering through downtown in my hometown of Olympia, WA.  At first glace it looks like an ordinary hedge; boxy to by sure, but nothing remarkable.

As I passed by though I noticed the hedge was actually a weeping Norway spruce (Picea abies ‘pendula’ – actually it could have been an ‘inversa’ – the repeated butchering made it hard to tell).  Either way, what could have otherwise been a fairly interesting plant had been reduced to a squared-off blob of blech.  The other side, of course, is that if a squared off blob of blech is truly desired there are cheaper and easier ways to achieve the effect.

The other example of the perils of not knowing your plant material comes from northern Michigan.   This case represents that other extreme of trees that grow too large for their space.  Here the homeowner wanted to screen his house (on the left but out of camera range to protect the guilty!) from the railroad track on the right of the photo.  Solution: Plant some conifers! Sounds like a good idea to me.

Only problem – the owner chose to plant the screen with dwarf Alberta spruces!  As with the blob of blech, the property owner could have achieved the desired screen in a couple of years and at a small fraction of the cost with seedlings from their local conservation district or seedling nursery.  In any event, we’ll check back in about 40 years and see how it’s working out for them…