Tuesday, January 29, 2013

Tree Planting and Drought

The impact of drought on trees has been in the news quite a bit lately including this story from USA Today. Which begs the question: since we are in the midst of a severe drought and since there is no way to know how long this drought may last, should we be planting trees? That is a very fair question, especially if we think about the potential issue of water scarcity. If it came down to a choice between planting new trees or trying to keep alive the ones we already have, then I would choose the latter. But I don't think that is a fair assessment ofthe situation. My hunch is we can do both - and indeed we must  do both.

Dead Ginkgo in Waverly
Something that can help inform our decision making today regarding tree planting in drought is to look back at the 1930s, when some of the hottest and driest years on record were recorded for this part of the world. Just think about this: on July 25th 1936, Lincoln reached a high of 116 F and the overnight low was only 91F - yikes! Back then the fear of drought and a changing climate actually spurred huge efforts at tree planting across much of the central US. In fact the Prairie States Forestry Project led to the planting of more than 220 million trees in shelterbelts and other plantings across the region. People realized the great value trees provided in taking the edge off the often brutal Great Plains climate.

Although I have come to love the wide-open expanse of this part of the world and feel we should do much more to conserve our prairie heritage, I would not want to live in a community without trees. They are vital to making our communities more comfortable, livable and beautiful. So I say yes! Let's plant more trees, even during times of drought. Our community forests are ever-changing and dynamic and require our constant attention at planting and care. With a changing climate that will almost certainly include more droughts and likely higher overall temperatures, it should be obvious to all of us that we need to adopt the best practices possible when it comes to tree selection, planting and care. A few suggestions that I would offer to help our tree planting endeavors would include:

1. Emphasize the planting of species that have proven drought survivability including bur oak, gambel oak, hackberry, juniper, Ponderosa pine, Osage orange, green ash, walnut, elm, etc. (Note: yes I did intend to include green ash here. Although we don't recommend the species for wide-spread planting due to the threat from emerald ash borer, the advancement of the pest across the region is relatively slow and many green ash trees will likely be alive for decades to come - especially in the western half of Nebraska).
Walnut is drought tolerant

2. Plant high quality root systems. Roots should be fibrous and laterally spreading, not circling at the bottom of a container.
3. Plant smaller trees more often. There are several factors at play here, but in general smaller nursery trees with good root systems are easier to establish in the landscape and generally become drought tolerant more quickly than larger specimens. There is nothing wrong with planting seedlings or even seeds, as long as those small plants can be protected in the landscape.
4. Plant properly! The first trees to die in any drought are the ones whose health was compromised for some reason. Common compromisers to good health in landscape trees include problematic roots and trees planted too deep.
5. Group trees together and encourage a healthy rooting zone. Trees grouped relatively close together help protect each other from weather extremes. And if the space between trees is maintained as nutrient recycling system with appropriate groundcover plants or mulch (not intensively managed turfgrass) the soil and rooting zone will be much better at conserving moisture and much healthier for the tree.
Planting a seedling can be good strategy.

For those who like Facebook, ReTree Nebraska is a good place to go for good tree spirit:

Tuesday, January 8, 2013

Redbud Reflections

 I live in an older Lincoln neighborhood and get the privilege of living near beautiful large trees. Notice I said near. You see, my block is devoid of most large trees and home to a few pears, some self-seeded elm, mulberry and crabapple seedlings, a few nice evergreens and a beautiful old Eastern redbud, which happens to be outside my balcony.  Cercis canadensis, a small understory tree native to Nebraska and much of the US extending east to the Atlantic ocean and south all the way to the Gulf of Mexico.  Most people can recognize it in the spring by the magenta flowers and summer by the heart shaped leaves.  There are some beautiful redbuds around this area.  There are also some that look so bedraggled that redbuds get a bad rap.  Usually it is because we stick them in wind swept sites with poor soil and throw up our hands when they don’t thrive.  In nature they grow in protected areas among large overstory trees. Other times it may because we picked one up from the local box store not realizing the seed source was from ‘down south’ and not adapted for Nebraska.  Since redbuds have such a large range there is a lot of variability so picking a tree grown from a ‘Northern’ seed source or even better a ‘Nebraska’ seed source will provide a tree that is adapted to our climate.  Then there are the trees that haven’t grown since we planted them which can happen when we move large nursery stock in a species that is extremely sensitive to being transplanted.  

Redbud in native Nebraska habitat

For the last year I have been doing a completely un-scientific observation of my redbud.  In the spring it is a favorite of honey bees. I can hear the hum from inside my place.  It is super sensitive to 2-4 D damage.  Curled leaves are a common sight in spring.  Mostly I am fascinated by the observation that it is LOVED by birds. I’ve hardly seen any birds in the pear trees, except for a Flicker that passed through last summer, stopping on the large, decaying Pear that is now gone. However the redbud, from dawn to dusk, brims with life. Chickadees, Juncos, Cardinals, Bluejays, Downy Woodpeckers, Nuthatch, Morning Doves, and an array of sparrow species.  I’ve even sighted a goldfinch in the tree and twice a hawk. These feathered friends spend a lot of time there eating the seeds, picking off insects, and jubilantly carry on.  I’m sure that it is not JUST because it is a red bud.  There are some dense shrubs near it, some wayward mulberry and elm saplings nearby, and a beautiful hummus and leaf filled bed below. Now I have feeders up, and the birds have ventured onto my balcony, giving my two cats and I quite a bit of entertainment.   Perhaps more than anything my year of observation has put Eastern Redbud higher on the list of trees to plant in the beneficial landscape.

Monday, January 7, 2013

The Amazing Bur Oak

Having observed trees in communities across Nebraska for many years, I've come realize that nothing beats the bur oak (Quercus macrocarpa) for beauty and survivability. It is truly an amazing tree. This native species is incredibly tough and adaptable, being able to grow on a wide range of soil conditions and tolerant of severe drought. We should plant the heck out of this tree!!
Bur oak along a street in Kearney.

In my home town of Kimball, I can probably count on my fingers and toes the number of bur oaks that have been planted. They all look wonderful! And yet the ugly Siberian elm dominates the landscape. Ugh! Kimball is certainly not unique in this regard. Indeed, bur oak is under planted across the state, and it gets worse the further west we go.
Bur Oak in North Platte.
Who says a bur oak is a slow grower? This one in North Platte is just a few decades old.
We need to plant more bur oaks - lots of them! Of course we should strive for species diversity across a community and we wouldn't want bur oak to outnumber all other species. But we have a LONG way to go before would ever be planting too many of these majestic trees. Indeed we could plant bur oaks until the cows came home and we still wouldn't have too many. This is partly because the cows come home more regularly than we give them credit for. But still...
Bur oak is beautiful throughout the year.

We should plant more bur oaks because they are tough, adaptable, ruggedly beautiful, long-lived, tolerant of our neglect, drought tolerant, ice-resistant, wide-spreading, shade-casting, climbable, dark green, naturalistic, loaded with wildlife, a friend of the squirrel, deer resistant, fire resistant, moderately flamboyant, tough like our forebears, poetic, inspiring, gracious, giving, fragrant, long-lived, friendly,... (I could add superlatives all day long!). More importantly, they are not Siberian elm, or green ash, or honeylocust, or silver maple, or any number of less deserving trees. They are bur oak: the king of our hardwood trees. Long live the bur oak!

The majestic bur oak "Josephine" in Petersburg Illinois. Abe Lincoln may have slept here!

Bur oaks can live for centuries - and will likely be the longest lived trees in our communities.

Thursday, January 3, 2013

Western Nebraska Town Trees

When I recently traveled to my home town of Kimball, Nebraska to partake in some holiday fun, I spent some time walking around town evaluating trees (and other things). It's tough to be a tree in western Nebraska where weather extremes are, well, extreme. Drought is frequent in this part of the world and in recent years, annual growing-season precipitation has frequently been less than 10"! In these conditions, trees are typically absent unless planted and cared for. One exception is the Siberian elm, that tough-as-nails tree that seems able to survive on dust and dog pee.

The number of street trees across Kimball has been in decline for decades.

For as long as I can remember, Siberian elm has been the dominant deciduous species in Kimball and in the less-cared-for parts of town it is often a very ragged and ugly tree, not doing the town any favors for its appearance. And yet for as ugly as it is, it is certainly providing the service of shade and shelter and wildlife habitat and a case can be made that it is better to have them than not. Though beauty is in the eye of the beholder, the outcome of such a debate would be far from certain as that tree is uuuugly!

Siberian elm is the dominant deciduous tree across much of Kimball.

Fortunately, if one takes a closer look at the trees of Kimball, it becomes pretty clear that there are other species proven tough and adaptable to the community. Colorado spruce is perhaps the second most dominant tree of Kimball and it rises prominently like green spires sprinkled throughout the community. These trees are especially noticeable as one drives down into Kimball from higher elevations to the north or south. Indeed, many visitors to town remark about the lovely spruce trees. Other proven evergreens include ponderosa pine and Austrian pine, both tough as nails stalwarts for the community.

Kimball is marked by many nice Colorado spruce trees.
My favorite tree for Kimball would be the bur oak (OK, its my favorite tree period). Though they are few in number, the bur oaks found here and there all seem to be doing well, many with no extra care or watering to survive the frequent droughts. Where they get just a little care, they are fantastic and are able to grow relatively quickly. If I lived in Kimball, I would set a goal of planting a large number of bur oaks across the community each year.

Bur oak should be planted more. Imagine if trees like this one from North Platte were more common across town. 

Some of the other deciduous trees of prominence around town include hackberry (of course), honeylocust, coffeetree, catalpa, American elm, green ash, linden, cottonwood and silver poplar. A species that really catches my eye and that deserves much wider use is black walnut. That is an amazing tree in its adaptability to tough conditions.  So come on Kimball - plant more trees including more of these proven and deserving species. And give them just a little bit more care.

The black walnut (left in photo) is doing well with very little care.