Urban Landscape Tree and a Carbon Neutral Future
Recent market trends have shown that renewable energy sources, (e.g., wind, solar) have begun to compete favorably with fossil fuels, based on price. While renewables have an initial advantage of offering nearly net-zero carbon emissions, serious questions remain regarding long-term, uninterrupted energy supply reliability. Short and/or long-term changes in wind and solar patterns could lead to what the authors called “energy droughts.” Using AI modeling, based on 70 years of historic wind and solar-power data, the authors calculated that such energy droughts could last days, weeks, months, or years. These conditions could persist far longer than current battery technology capacity, making long term back-up energy storage from these sources difficult and, potentially, impossible.
Renewal energy alternatives were never envisioned as a complete solution to our long-term challenge of creating a future less reliant on non-renewal options. Demand reduction continues to hold the greatest, simplest, and most decentralized approach to a less fossil energy dependent future. It is in this arena that urban forests, the thoughtful construction and durability of the built environment, and the application of state-of-the-art biotic and abiotic materials by landscape architects will play a critical role. The emergence of LEED certification and an increased emphasis on sustainability across a wide range of design and construction professions shows the critical roles architecture, landscape architecture, landscape construction and maintenance, arboriculture and related horticultural professions will play in energy demand reduction.
Landscape trees serve multiple roles in energy demand reduction and climate mitigation by active carbon/CO2 and particulates sequestration, shade that reduces the impact of heat islands, by creating a more pedestrian friendly urban environment the encourages people to walk rather than drive, and having a calming influence on pedestrians and drivers, alike.
For our urban forests to meet the challenges of the built environment and remain impactful, communities must not only continue to plant additional trees but to embrace tree production, landscape design and landscape maintenance practices that insure the longevity of all the trees in the urban forest. Well distributed, proportional root systems, appropriate placement of trees within the landscape, irrigation system design, and scheduling, and professional pruning and fertilization are all crucial in creating and maintaining a vibrant, durable landscapes.
The challenge for AZT is to continue to develop clonally propagated desert-adapted tree varieties, innovative production methods, and promoting policies and practices that support sustainable landscapes. Over the last 25 years we have introduced 11 new trees under our “Variety AZT” name. These include 3 Desert Willow varieties, Thornless Mesquite, the only cloned Native Mesquite, Ironwood, Seedless Mesquite, and Sonoran Palo Verde. In addition, we produce Thornless Honey Mesquites and, Thornless Palo Verde.
Our production methods include our Root Management System that fosters distributed root systems at each progressive step in tree production (from liners all the way up to 48” boxes). Tree selections to be added to our “Variety AZT” clones are evaluated, over a period of years, for cold hardiness, branch angles, flower quality and quantity, pest and disease susceptibility, growth rate, and mature stature. The combination of a rigorous clone screening program and our integrated production methods ensure that the trees we bring to market can, with proper planting and maintenance, become a long lived, vigorous and attractive addition to any landscape or urban forest.
Moving from dependence on non-renewable energy sources to renewables will require both large and small levels of innovation, the integration of highly sophisticated and relatively modest technologies, and changes in our fundamental attitude towards energy consumption. Over the last 40 years horticultural professionals in the desert southwest have consistently demonstrated the resourcefulness and imagination to move from a landscape aesthetic that ignored the beauty of our surrounding Sonoran Desert to one that embraces and celebrates it. In this effort, landscape professionals have addressed the need to conserve water without compromising beauty, diversity, and the abundance of color that desert natives provide. Our industry, in all professions, has shown an extraordinary ability to adapt, reimagine, and embrace change.
Quality and permanence are never the product of luck. Durable, vigorous, and attractive desert-adapted landscapes are the convergence of professional design, proper planting and maintenance, and high-quality trees and shrubs. If the past is prolog, Arizona landscape professionals, (growers, landscape architects, landscape construction and maintenance experts and arborists) will continue to play critical roles in producing built environments that are attractive, sustainable, and create a unique sense of place in our desert home.