The fall foliage season is well under way. Enjoy the yellows and oranges and purples of ash leaflets already mostly on the ground.
Take serial trips to Johnson Woods Nature Preserve near Orrville in the next few weeks to enjoy the light show of yellows and golds of the sugar maples there. Now you can still see spots of yellow, orange and gold amid the green of these leaves as the chlorophyll pigment breakdown proceeds at an uneven pace; soon the overall shimmering gold will light up the woods.
Speaking of the chlorophyll pigment in the leaves, remember its crucial environmental role in the way our planet functions. In fact, let us ponder the most fundamental role in how trees and other plants matter from an energy production perspective. Then we will turn to ways that planting trees can help conserve our use of energy. First, production.
Trees and energy, part 1
The primary function of plant leaves is food production. This occurs through the wondrous process of photosynthesis. Light energy from the sun (or another source) is absorbed by that green-reflecting chlorophyll pigment in leaf cells and with adequate carbon dioxide from the air and water from the soil the result is — sugar. This carbohydrate energy source is the food that fuels the rest of the plant processes including protein synthesis and respiration.
Photosynthesis is a wondrous thing because it starts the food chain that allows life on earth as we know it, including our own survival.
The food chain starts with plants harnessing the energy of the sun and converting it to plant growth that is then eaten by animals and animals that eat other animals and so on.
This photosynthesis is done by trees and shrubs and herbaceous plants and grasses and a number of other primitive plants such as phytoplankton. The result: trees and other plants are in a fundamental way our most basic energy source. Photosynthesis rules!
Trees and energy, part 2
Another important way to think of trees and energy is their capacity to conserve energy, as in energy savings of fossil fuels. How so? This conservation relates to the age-old horticultural maxim of planting the right tree in the right place. In one sense this relates to matching plants to their sites in terms of soil type, sun exposure, size and location conflicts such as not putting a tree that will eventually tower over the landscape under power lines, and so forth, but it also relates to siting trees for most efficient energy use.
Deciduous trees, those that lose their leaves in autumn, most obviously help save energy in the summer by providing shading and thus less air-conditioning usage. Evergreen trees most obviously conserve energy by lessening the cooling effect of winter winds, thus saving significant amounts of fuel for winter heating.
The details of this are important, for example in our part of the country, it is recommended to plant deciduous trees to shade east-facing walls and windows that are exposed to sun in the morning and west-facing walls and windows that are exposed to afternoon sun. This has more effect than planting trees at south and north exposures relative to buildings.
There are areas of the country where the energy savings are considered so important that, for example, the Sacramento Municipal Utility District in cooperation with the Sacramento Tree Foundation have programs that provide funds to buy trees for homeowners that site trees correctly. Trees also provide some direct energy-saving benefits. As evergreen and deciduous trees transpire, with water evaporating from leaves, the cooling effects of this evaporation cools the air around the trees, much like cooling pads in greenhouses and air-conditioner systems.
A new tool for understanding the details and maximizing the energy savings of trees is a program known as Energy Saving Trees developed from the iTree models of tree benefits by the Arbor Day Foundation and their private partner, the Davey Tree Expert Company of Kent.
This tool helps individual homeowners and communities determine which trees matter most and how tree placement matters relative to energy savings. As noted on the energysavings.arborday.org website, proven energy savings benefits of trees include:
“1.) Properly planted trees can save homeowners up to 20% on their energy bills. 2). The City of Sacramento is saving 13,500,000 kWh of electricity every year from strategic tree planting. 3). In addition to energy savings these trees will provide tangible benefits for the entire community such as improved air quality, reduced stormwater runoff, a lower urban heat island affect, and a lower carbon footprint.”
As Greg Ina, vice president and general manager of the Davey Institute of the Davey Tree Expert Co. notes: “With the 5.0 Version of iTree and its iTree Design component (check out iTreetools.org) we have moved beyond simple recommendations, e.g. to avoid power lines, to a science-based plant siting tool at the homeowner’s level, in order to optimize tree placement and selection to best provide energy savings.”
The iTree program is working to add utilities from around the country and in Ohio to increasingly improve the function of the model based on local energy costs to best estimate actual energy savings in your yard.
I checked out these sites and from the iTree Design site, entered my Wayne County address, got the latest Google map, which was indeed pretty recent, since our Presidential Election signs (just added in the last two weeks) were in the image.
It is informative and fun to enter basic data and then use the tool to draw a building footprint and determine the benefits of current trees from the image but also “virtual” trees and what their benefits would be in upcoming decades if you planted them now.
Trees and energy. Very cool — and warming — in the winter. As Jim Currie, director of the ATECH program at Ohio State University’s Agricultural Research and Development Center in Wooster notes:
“It’s important to think of trees in the context of energy in a variety of ways. Increasingly, trees and ‘biomass’ are talked about as possible sources of ‘bio-fuels,’ but it’s equally important to consider the energy benefits they provide naturally with no conversion or processing.”
Back to the beginning.
As Robert DeFeo of the National Park Service said: “The most important chemical reaction on earth is photosynthesis … We are all parasites upon it.”
Jim Chatfield is a horticultural educator with Ohio State University Extension. If you have questions about caring for your garden, write: Jim Chatfield, Plant Lovers’ Almanac, Ohio State University Extension, 1680 Madison Ave., Wooster, OH 44691. Send email to firstname.lastname@example.org or call 330-466-0270. Please include your phone number if you write.