By Morgan Erickson-Davis
Nations are hurrying to reduce greenhouse gas emissions and slow global warming, and one way they’re going about this is by encouraging the protection of forests. Trees trap carbon in their biomass and in the soil, and it’s hoped that keeping them in the ground will keep their carbon out of the atmosphere.
Climate-focused forest conservation policies and programs tend to be focused on rainforests. Covering vast areas, rainforests have earned the moniker “lungs of the planet” for their ability to sequester carbon dioxide while producing oxygen.
But pound for pound, other types of forest give rainforests a run for their money. A hectare of mangrove, for instance, can store four times more carbon than can a hectare of rainforest. And now, new research shows that even temperate forests in cities may be able to sequester nearly as much carbon as a similarly sized area of rainforest.
The study was conducted by a team of scientists from University College London, who mapped the carbon stores of areas of tree cover in the London Borough of Camden. Their results were published recently in the journal Carbon Balance and Management.
The team used remotely sensed LiDAR (which stands for “Light Detection and Ranging”) data that provided high-resolution information about tree structure. Armed with specific numbers on the dimensions and extent of Camden’s aboveground biomass (i.e., the parts of trees that aren’t underground), the researchers were able to estimate how much carbon is contained in each pocket of urban forest.
“Urban trees are a vital resource for our cities that people walk past every day,” said lead author Phil Wilkes. “We were able to map the size and shape of every tree in Camden, from forests in large parks to individual trees in back gardens. This not only allows us to measure how much carbon is stored in these trees but also assess other important services they provide such as habitat for birds and insects.”
Their results indicate Camden’s trees contain more carbon than estimated by previous studies. And while, as a whole, the borough’s median carbon density is on the low side when compared to many natural ecosystems – roughly equivalent to subtropical steppe – its urban forests are carbon storage powerhouses. The maximum value they uncovered was in a large, 320-hectare park called Hampstead Heath. There, carbon density approaches that of tropical rainforest.
By James Barron
The city has 10,542 acres of forests. The Natural Areas Conservancy, which says they are at a tipping point, is thinking about how to care for them.
Sarah Charlop-Powers was comparing New York City’s forests to its subways.
The city has more than 840 miles of tracks for one. It has 10,542 acres of the other, about half as much as the Congaree Swamp in South Carolina, a small national park with an old-growth forest and, according to the website I Love National Parks, “more bugs than you can imagine.”
No doubt there are many bugs in New York’s forests, even cockroaches that have yet to find their way to somebody’s basement or bathtub. But Ms. Charlop-Powers, the executive director of a Manhattan-based nonprofit group called the Natural Areas Conservancy, is not focused on them. She sees the trees — and the forest. Most of the city’s forest is deep in parks, and on the worry spectrum, she is “concerned” about them.
“The situation is not dissimilar to the subways, in that we’re at a crucial moment,” she said.
Fortunately, urban forests appear to be at the point the subways reached decades ago, before transit policymakers decided that maintenance could be deferred.
BY TEE CLARKSON Special correspondent
As a city of considerable age, Richmond is fortunate to have a significant number of older trees in varying densities across the landscape.
The importance of these trees, particularly in urban areas, is substantial.
“We are way past the hippie, tree-hugger mentality when it comes to the benefits of urban trees,” said Joel Koci, an associate with the Urban Forestry Extension at Virginia State University.
“We have real science to back up the benefits of urban forest.”
Koci pointed specifically to the benefits of trees in sequestering carbon in leaves, trunk and root systems, the absorbing of particulate matter such as harmful chemicals and heavy metals, the absorbing of solar radiation, as well as the reduction of storm water runoff and erosion.
By Dean Fosdick | AP
Landscape designers in cities are creating quieter living spaces by using trees to mute loud noises like sirens and air brakes. It’s called “soundscaping,” and it aims to restore peaceful, natural sounds like wind whispering through leaves, birds chirping or rain dripping from branches.
“Massive walls are often installed to quiet freeway noise in major cities, but there are more aesthetic ways to handle it,” said Tim Moloney, who teaches landscape design at the University of Missouri. “Use vegetation for minimizing the background clatter.”The denser a tree’s lower branches, the better it masks or deflects bothersome noise, Moloney said. Evergreens are the preferred vegetative sound barriers because they are densely branched and are attractive year-round. Ideally, shrubs would be a major component of any green muting mix.
Planting trees is a cost-effective way to tackle urban air pollution, which is a growing problem for many cities.
A study by US-based The Nature Conservancy (TNC) reported than the average reduction of particulate matter near a tree was between 7% and 24%.
Particulate matter (PM) is microscopic particles that become trapped in the lungs of people breathing polluted air.
PM pollution could claim an estimated 6.2 million lives each year by 2050, the study suggests.
Lead author Rob McDonald said that city trees were already providing a lot of benefits to people living in urban areas.
As humans continue to urbanize — more than half of us now live in cities — it becomes critically important to restore and conserve urban trees in harmonious coexistence with nature. Many “smart” cities have been doing this for years, of course, and some of the results have been impressive.
Much of this discussion and the overarching history and legacy of city trees is covered by author and historian Jill Jonnes in her recently published Urban Forests: A Natural History of Trees and People in the American Cityscape (Viking).
“Nature’s largest and longest-lived creations, trees play an extraordinarily important role in our cityscapes, living landmarks that define space, cool the air, soothe our psyches, and connect us to nature and our past,” Jonnes writes on her website. “Today, four-fifths of Americans live in or near cities, surrounded by millions of trees, urban forests containing hundreds of species. Despite the ubiquity and familiarity of those trees, mostof us take them for granted and know little of their specific natural history or civic virtues.”
Last Friday, students from St. Nicholas Catholic School got out of the classroom to help the former 10,000 Trees Project launch into its next phase as the rebranded Ten Thousand Forests project. The tree plant ceremony took place at the nature centre at the Laurel Creek Conservation Area.
“We’re passing on the shovel to the next generation,” said volunteer Rick Relf, who has been part of the organization for about as long as program founder, city Coun. Mark Whaley.
Beginning about 15 years ago, Whaley wanted to make Waterloo greener. So, he came up with a goal — plant 10,000 trees in 10 years on city land.
That goal was surpassed in 2007, faster than anyone expected, and 10,000 Trees, and its army of volunteers, kept at it.
“We’ve decided to put away the counter and keep planting,” said Whaley. “We have a new team of young, high-spirited and successful volunteers. They’re bigger thinkers and have bigger goals to make a difference.”
Ten Thousand Forests also has a new executive director, Tessa Jennison. A Waterloo native, Jennison earned her Bachelor’s degree in urban and regional planning at the University of Waterloo.
Urban forestry experts have long suggested that tree canopy cover in residential and urban areas is essential to maintaining a healthy ecosystem in those communities, but a new study suggests that tree cover may also contribute to increased property values.
The researchers found that the contribution of tree cover to real estate value maximizes at about 30 percent cover at the property level and about 38 percent at the county level. Perceived benefits, such as scenery, privacy, shade, and recreation, all contribute to this rise in property value.
Officials say unselective species of trees have been planted across Kigali – the capital of Rwanda – and other towns around the country with no regard to international standards for urban forestry. It is against this background that the government has embarked on formulating a policy, which will complement the Kigali City Master plan and the national green-growth agenda. This is so property developers also get to plan for urban afforestation while putting into consideration specific species of trees to grow in cities and towns.