Tall Pots in a Shallow World

Transcription

1 Tall Pots in a Shallow World Scientists have figured out how to restore damaged urban desert landscapes with native plants that use less surface water and prevent erosion. Problem is, the scraggly little saplings with long roots just aren t as pretty as their conventionally grown counterparts. Wayne Warrington I m drawn to the call of frogs congregating on a environments. But the Flood Control District of Mari- lone desert tree - the only dry anchor they can copa County hopes to combat the destruction. One find. The tree stands isolated, on an island cut tree at a time. from recent eroding floodwaters. A muddy river now separates me from this last tree standing in a landscape scoured by downed limbs, tumbling rocks, and long discarded man-made debris. Yesterday, this expanse of desert in Maricopa County was silent, dry, and sparsely vegetated. The natural desert plants must have been cleared years ago for a farm or perhaps a housing development on the edge of Scottsdale. Now it s barren land. Had the native mesquite, creosote, palo verde, rabbit brush, and various cacti been left undisturbed, the established network of deep native plant roots may have weakened the recent torrent s damage. Unfortunately, damaged landscapes like this are common in disturbed desert

2 An obscure and time-tested solution The salvation of flood-ravaged desert landscapes lies in an obscure but time-tested planting method for native plants. A decade ago, the county embarked on an experiment to plant native trees and shrubs in tall pots, hoping to create plants with more robust root Such an anchor provides additional support for fledgling or established trees in fierce winds that can occur during the height of monsoon storms. Anchored plants also hold soil in place and retain healthy populations of vegetation, allowing wildlife, like chorusing frogs, to remain dispersed, instead of clinging to islands. systems better adapted for our arid climate. Since native plants have a natural propensity to create root structures that seek ground water dozens of feet below the surface, it made sense to pot new desert plants in a way that encouraged long root structures. The tall pot nursery Harry Cooper, the Flood Control District s landscape architect, inherited the tall pot experiment in His inheritance included a tall pot tree nursery, an office stocked with bookshelves and file drawers containing Conventional growing methods, conversely, create related materials, and a collection of digital data. unnaturally dense balls of matted roots. While they I met with Cooper early on a windy morning in mid- October, in the Flood Control District building in the county complex in south Phoenix. Smells from the landfill directly to the south become noticeable each time the wind picks up. may be hearty to start with, they struggle with a shallow root structure in the harsh environment of the Sonoran desert. But the rub is that native plants transplanted from tall pots are not immediately pretty. During the early growing phase, plants transplanted from tall pots have reduced foliage, thanks to their long roots. Cooper s voice is deep and gravely, and his professionally proper greeting reinforces his serious demeanor. The longer root structure allows vegetation to anchor itself in the desert soil, while reaching for the water table that may lay dozens of feet below the surface. I m interested in looking at his data, but he s eager to showcase the tall pot nursery. We cross the agency parking lot to a fenced off plot of land marked

3 Maricopa County Flood Control District Tall Pot ingenuity and successful persistence. Nursery. He unlocks the gate and leads me to rows of vegetation growing in 30-inch sections of PVC pipe. Standing amongst the scraggly sapling and yearling trees, I wonder where the notion of incubating native plants in tall pots began. If climate changes, tall pot plants will fill valuable role If monsoon storms continue to intensify and prolonged high temperature periods increase, plants grown with minimal water and robust roots will fill a valuable role in and around Phoenix. The modern development of growing methods emphasizing elongated roots had originated in southern California during the 1980s in experiments in arid lands restoration. The tall pot tubes surrounding Cooper and me were developed from planting practices started in Joshua Tree National Park, were improved by research conducted by David Bainbridge in San Diego, were transported to Arizona by way of revegetation specialists at Arizona Game and Fish Department, and were shared with the Center for Native and Urban Wildlife at Scottsdale Community College before ultimately being embraced by Maricopa County s Flood Control District. And, while it s still relatively unheard of today, it boasts an enviously high survival rate. Richard Adkins, forestry supervisor for the city, is charged with managing its urban forest. In an interview with azcentral.com, Adkins admits that the largest challenge he faces is lack of citizen awareness of the existence and benefit of Phoenix s urban forest. Surprising and frustrating, since a 2013 inventory documented over 92,000 trees, palms, and tall cacti within the city. The U.S. Department of Agriculture says urban forests cool cities, save energy, improve air quality, strengthen quality of place and local economy, reduce storm water runoff, improve social connections, help promote smart growth, and create walkable communities. With such tangible benefits directly available from a wellmanaged urban forest, public funds should be pouring Once considered impractical and improbable, arid lands restoration projects have become examples of into Adkins office. Unfortunately, they do not. As azcentral.com points out, the city designates funds for the maintenance of established trees in its urban forest, but

4 not for the planting of new trees, or even for replacement of lost trees. While tall pot plant use in urban areas may remain a challenge, their suitability for restoration projects is being properly utilized. The Flood Control District s In an , Adkins writes he s familiar with the benefits of tall pots and if the opportunity to utilize tall pot material for a project was to arise, I am certainly in favor of using the material. nursery maintains the ability to grow 8,500 trees at a time and typically coordinates two to three restoration efforts each year in conjunction with their flood control construction projects. Given the ability of tall pot vegetation to thrive in arid environments with minimal maintenance and limited irrigation, the connection between Richard Adkins, the forestry supervisor, and Harry Cooper, the flood control district s landscape architect, should be an instant At least with these efforts I may find myself once again listening to frogs in the desert after a summer storm. This time, however, thanks to tall pot plant restoration, I will hopefully stroll through a grove of trees, instead of standing staring at just one. win. Adkins says in an that public preference dramatically favors top growth when selecting plants for residential or commercial use. Cooper, surrounded by his nursery saplings, emphatically and disappointedly agrees. Despite the demonstrable superiority of tall pot trees in dry desert environments, these plants are not mass-produced because there s just not a market for them. They are not as aesthetically pleasing as conventionally grown plants when first transplanted.

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