Tuesday, March 6, 2018

Silent Sentinels: Tree Diversity and you

"Take a look at my grave where I have become the berries on the juniper"
Chuang-Tzu (399 - 295 B.C.)

 You say "Denver Botanic Gardens" and people think of our York Street site. But we co-manage a remarkable garden at nearly 12,000' on the broad shoulders of Mt. Evans (a subsidiary peak called Mt. Goliath). I know garden implies the hand of man (and woman!), and at this point, I am not the only one to point out that there's not a square centimeter on this enormous sphere whose slender filmy crust we occupy that isn't impacted by humans. Nature is our garden. Alas.

I doubt that these dead bristlecones died because of us. But the very first scientific expedition to Colorado 198 years ago caused a fire on Pikes Peak that burned much of the treeline forest at that time, and there is still evidence of it. Trees that survive are here but for the good grace of humans not having mucked them up yet. If you have never read Chuang Tzu (or Zhuang zi in the proper Pin Yin), you will realize how much philosophy has been inspired by trees in Asia where so many of our street trees (and their pests) originate!

Acer triflorum at Denver Botanic Gardens

Not everyone likes baseball, or television or your favorite band. But everyone loves trees (if you don't you're a damn fool). They provide us oxygen that we breathe. They grow to cast refreshing shade that reduces our air-conditioning costs immeasurably in summer, not to mention providing a welcome haven to lie under.

Red admiral butterfly on Abies koreana 'Silberlock'
 They produce no end of food for the birds and the bugs the birds need to live on. And they provide us with delicious food as well, don't forget! Their severed bodies are the stuff civilization is built with, and this is just barely scratching the surface of the enormous benefits that trees provide. They help filter our filth we dump on the soil. They mitigate the rain that would flood much worse without them. They paint our cities pastel colors in spring, a vast range of greens in summer and fiery expressionistic hues in fall. But in the winter months when they stand naked and gaunt  while we muffle ourselves and scurry home to cocoon, then they reveal their sinewy majesty of form that shames the feeble structures that humankind dares erect in their stead.

Pinus tabuliformis at Denver Botanic Gardens

For all our talk about trees, we've not done as well by them as we could: we plant vast monocultures of American elms that succumb to a fungus, and we replace these with a vast monoculture of ash trees, which are now doomed to succumb to a beetle in the coming decade, costing hundreds of millions, perhaps billions of dollars to remove just in Colorado. If you think education is expensive, try ignorance!

On Thursday, March 15 there will be a day to explore the subject of tree diversity in our cities: it will be the 5th of its kind that we've staged featuring many of America's premier tree experts. This year Andrew Bunting, assistant director and director of plant collections of Chicago Botanic Garden will speak to "Small Ornamental Trees: Versatile Plants for Difficult Locations".  Kristopher Stone, director of Boone County Arboretum in Kentucky, will provide "Observations of Trees, Climate Trends and Industry Support". David Temple now lives in Cortez, Colorado but grew up in Denver, a student of Earl Sinnamon (whose gift provided Chatfield with its fantastic visitor Center).  David managed a successful Tree care company for many decades before establishing a large nursery of the best adapted trees for our region: he speaks on "Ten Trees that should be used more in the Rocky Mountain region". Keith Wood, State Forester for Colorado, will report on a unique research project on "24 years of Tree Growth in Westminster, Colorado"...Click here to find out more....

Homeowners and landscape professionals can all gain great benefit from this celebration of trees.

I end with perhaps my very favorite tree poem ever (first in Spanish, then with my translation) by Antonio Machado (1875 – 1939).

VIII (from "Campos de Soria")

He vuelto a ver los álamos dorados,                      I have come back to see the golden cottonwoods,
álamos del camino en la ribera                              Cottonwoods along the road above the bank
del Duero, entre San Polo y San Saturio,              Of the Duero, between St. Polo and St. Saturio,
tras las murallas viejas                                           Across the ancient walls
de Soria barbacana                                                 Of graybeard Soria,
hacia Aragón, en castellana tierra.                         Towards Aragón in the land of Castile.

Estos chopos del río, que acompañan                    These poplars of the river, which accompany
con el sonido de sus hojas secas                            With the sound of their dry leaves
el son del agua, cuando el viento sopla,                The murmur of water when the wind stirs,
tienen en sus cortezas                                            They have, upon their trunks
grabadas iniciales que son nombres                       Engraved initials that are names
de enamorados, cifras que son fechas.                   Of lovers, numbers that are dates.

¡Álamos del amor que ayer tuvisteis                     Cottonwoods of love that yesterday had
de ruiseñores vuestras ramas llenas;                      Nightingales filling your branches!
álamos que seréis mañana liras                              Cottonwoods! That tomorrow will be lyres
del viento perfumado en primavera;                      Of the wind perfumed with springtime!
álamos del amor cerca del agua                             Cottonwoods of love nearby the water
que corre y pasa y sueña,                                       Which flows and goes and dreams.
álamos de las márgenes del Duero,                        Cottonwoods on the banks of the river Duero
conmigo vais, mi corazón os lleva!                       You'll come with me, my heart will take
                                                                                    you with me.


  1. Some of the best gardeners are not human. Bees, Ants, and even fungi shape their environments more intricately than people.

    There are some things that don't like trees. The biggest example is grassland birds. They won't nest anywhere near a tree. In areas being managed for grasslands trees are not appreciated. Colorado has a good share of such grasslands.

  2. Many of us are very concerned with the preservation and restoration of shortgrass and midgrass prairies in the Denver area, James: there are very few little fragments left in the Denver area proper, and I'm getting together a consortium of those who manage them to help fortify one another in the face of the truly astounding forces of "development" that have so transformed our region in the few hundred years of European settlement. The actual urban setting, however, is the antithesis of prairie--except for the possibility of re-creating bits of prairie on roofs: Denver has passed a sweeping and very bold green roof initiative that may in fact lead to that end. But trees and an almost eastern woodland environment (which exists in nearby canyons and along the rivers naturally) is essential for cooling and comfort in the cities: like it or not, we as humans have altered and will continue to alter vast swaths of the earth's surface. I too would like to limit our footprint, but footprint there shall be in any case.

  3. The bristle cone pines are indeed magnificent. Just as are the small scraps of original prairie that remain. Once destroyed, both are unable to be returned to the original condition despite people dedicating a lifetime to it. What cannot be replaced should be valued most.

    The roots of tall grass prairie provides cooling by evaporating water from deep in the ground. Prairie vegetation is also better at filter water and preventing erosion than trees. The only thing prairie does not provide is high shade. I think prairie vegetation is something that should be utilized more in urban landscapes for green infrastructure. However, I understand urban trees have a bigger following at the moment.


Featured Post

A garden near lake Tekapo

The crevice garden of Michael Midgley Just a few years old, this crevice garden was designed and built by Michael Midgley, a delightful ...

Blog Archive