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“Log” some trees and raise a toast as we launch the Urban Forest Map!

After countless hours, gallons of tea and coffee, millions of keystrokes, and far more hours with databases than with trees, it’s time to celebrate! Come join our team and show your tree-loving support, as we celebrate the launch of the Urban Forest Map on Earth Day.

We’ll drink a toast to the project and especially to our sponsors, chat about the beauty and wonder of trees, splash the Map up on the wall so you can add trees, and eat, drink, and be merry!!

It won’t be the same without you, so we hope you’ll be able to stop by.

Energy conservation is perhaps the most valuable of the ecosystem services that trees provide. Why? Because it has trickle-down effects that amplify other benefits, like air quality improvement and carbon sequestration. But we’ll get to those later this week. For now, let’s talk about how trees help save energy.

Trees help reduce energy used for cooling in three main ways:

• Shading reduces the amount of heat that reaches buildings.
• Shading of heat-absorbing surfaces like parking lots, roads, roofs, and sidewalks helps reduce the “urban heat island” effect. These manmade surfaces can increase city temperatures as much as 8-10° above the surrounding natural areas.
• As trees take in and give off water (evapotranspiration), they use up solar energy that would otherwise heat the air. Over large areas of trees, this effect can be substantial.

Trees also help reduce energy used for heating:

• Reducing windspeed reduces the movement of colder outside air into buildings.

What kinds of impacts can we expect in San Francisco?

In all honesty, the energy conservation benefits of trees in San Francisco will likely be lower than just about anywhere else! Why? Mainly because of our very mild climate. Few San Francisco buildings even have air conditioners, so there aren’t so many opportunities to reduce air conditioning use, and it’s rarely cold enough to require heat.

A 2003 study [PDF] on the street trees of San Francisco estimated that the average tree here reduces energy consumption by only about $1. Compare that with the results of a similar study in Berkeley [PDF], where warmer temperatures and bigger trees yieled energy benefits that were 15 times higher.

Still, there are a lot of ways we can plant trees with energy conservation in mind. In a future post, we’ll talk about how to get the most out of your trees with special emphasis on the unusual circumstances of San Francisco. And remember, one of the coolest things about the Urban Forest Map is that it will help estimate how much energy the trees of San Francisco are conserving. Once you've added a tree (with its trunk diameter and species), we'll calculate the energy benefits and add them to the city total.

For more information on how trees help conserve energy and how and what to plant to maximize benefits, visit the Center for Urban Forest Research’s website and check out these two research summaries [PDFs]:

But we might not always appreciate just how much work trees are doing to improve our environment. They help clean the air of pollutants, reduce our energy consumption, filter stormwater before it reaches the Bay, and reduce atmospheric carbon dioxide to help fight climate change. In other words, they provide valuable services that help the ecosystem function properly.

Scientists at the US Forest Service’s Center for Urban Forest Research (my former employer!) have been working for decades to quantify these ecosystem services, so that we can have hard data to back up our intuition that trees are awesome (and to help policy makers understand their value). We’re making use of their research to provide what I think is one of the coolest features of the Urban Forest Map—its calculations of these ecosystem services––so you can see how hard the trees in your backyard or in your neighborhood or across San Francisco are working. 

So, consider this an introductory post. For the rest of the week, I’ll tackle each of those four aspects I mentioned above, explain how trees do what they are doing and give some numbers from a recent study of San Francisco done by the Center for Urban Forest Research. In the future, we’ll talk more about less tangible benefits (like wildlife habitat, effects on health, sense of place) too.

Here’s the basic mission of the project:

The Urban Forest Map is a collaborative project among city agencies, tree advocacy groups, and you -- the citizen foresters and nature lovers of San Francisco -- to build an inventory of San Francisco’s urban forest one tree at a time. Just log in online, click the map, and add the trees near you! For each tree added, we’ll calculate the environmental benefits its providing -- how many pounds of air pollutants it’s capturing, how much energy it’s helping conserve, how many gallons of stormwater it’s filtering, and how much carbon dioxide it’s removing from the atmosphere. As we build an inventory together, the information will help planners, city arborists, ecologists, tree advocates, and residents protect and grow the urban forest.

Here are a few thoughts for a motto that we had to help get the ball rolling:

• Tree by tree
• What trees are your neighbors?
• One tree at a time
• Turning gray into green!
• Map your urban forest!

So what do you think? Add your motto in the comments here, or on our Facebook Page, and we’ll take it into consideration! Thanks!

But there really is such a thing as the urban forest (after all, it has a Wikipedia entry, so it must be real [link to http://en.wikipedia.org/wiki/Urban_forest]) and our cities would be much poorer without it.

For some people, the definition of an urban forest is the trees within a city.  But just like a wildland forest is more than just trees, I see the urban forest as:

• The trees
• The other vegetation (everything from the lawns of Golden Gate Park to the shrubs and flowers and grasses in our backyards to the tomato plants and pansies on a high-rise balcony)
• The soil supporting all of these
• The birds, animals, insects, microbes, fungi that make their homes among these

And that’s just form. The urban forest is about function too. It works to clean our air and water, fight climate change, conserve energy, and provide food and shelter for humans and other organisms.

For those who have trouble wrapping their brains around the concept of an urban forest -- try imagining a city without the trees. Pretty unimaginable, isn’t it?

• Problems keeping up with tree inventories (tree people like to plant trees not enter data)
• Problems with technology (like proprietary software products with bad support or expensive software packages)
• Problems with lack of technology (we’ve seen cities where they keep tree records on index cards in drawers or in three-ring binders)
• Difficulties coordinating among different government entities (in San Francisco there are more than a dozen local, state, and federal agencies with jursidiction over trees)
• Neglect of the importance and value of trees on private property (for logistical and cost reasons these are rarely, if ever, counted in an inventory).

And yet, knowledge of the urban forest -- where the trees are, what species are represented, how old and healthy they are, the distribution of trees geographically -- has great value for planners, city foresters, ecologists, landscape architects, tree advocacy groups, and residents, too.

Our goal with the Urban Forest Map is to provide a one-stop repository for tree data, welcoming information from any agency or group and enabling and celebrating citizen participation. Together we’ll work toward building a complete, dynamic picture of the urban forest.