Category Archives: Conservation
Eric Jaffe, writing in the online news magazine The Atlantic Cities (a spin-off of what used to be called The Atlantic Monthly), reports on the findings of a new study in Urban Forestry & Urban Greening.
Using aerial photographs to compare changes over time in 20 major U.S. cities, researchers David Nowak and Eric Greenfield of the U.S.D.A. Forest Service found that tree coverage is on the decline, while impervious cover — roads, buildings, sidewalks, and the like — is on the rise:
Tree cover in 17 of the 20 analyzed cities had statistically significant declines in tree cover, while 16 cities had statistically significant increases in impervious cover. … City tree cover was reduced, on average, by about 0.27 percent/yr, while impervious surfaces increased at an average rate of about 0.31 percent/yr.
Nowak and Greenfield collected recent digital aerial images for at least 1,000 random points in 20 large American cities, and coupled them with images at the same points from roughly 5 years earlier. Trained photo interpreters then classified the various types of coverage at each point: tree coverage, grass coverage, building coverage, and so on.
Their subsequent analysis showed clear trends away from tree coverage and toward impervious coverage. All but three of the cities had a statistically significant loss in tree coverage, with two others showing a non-significant loss (essentially no change). Houston (3 percent) and Albuquerque (2.7 percent) suffered some of the biggest loses. Only Syracuse showed a gain in tree coverage — and that of 1 percent.
Mike Shanahan (Under the Banyan) reports on the rapid decline of seed dispersing and other animals in the world’s most botanically diverse forest. (And no, it doesn’t have anything to do with that bug-bear of northern-hemisphere conservationists, overpopulation, as he details in a comment.)
Urban tree news: Pittsburgh’s master plan, San Francisco street trees on their own, and the eucalopalypse
There’s some big news about urban forestry coming out of Pittsburgh and San Francisco over the past two weeks.
- An organization called Tree Pittsburgh is at work on that city’s first ever Urban Forest Master Plan, and is now soliciting public input. Since a majority of the city’s trees are privately owned, public buy-in will critical.
- As of last week, San Francisco’s Department of Public Works is no longer responsible for the city’s 23,000 street trees. Their maintenance and upkeep costs are now up to local residents.
- And also in San Francisco, the long-simmering battle over the fate of the thousands of non-native, invasive eucalyptus trees is heating up. What’s a tree-hugger to do when entire regions become taken over by trees with low value for native wildlife species?
Thanks, by the way, to Georgia Silvera Seamans at the local ecologist blog for sending these (and many other recent links) my way.
We tend to pass on newspaper stories in favor of blogs here, but this Guardian story is too important to ignore.
The biggest trees in the world, known as the true ecological kings of the jungle, are dying off rapidly as roads, farms and settlements fragment forests and they come under prolonged attack from severe droughts and new pests and diseases.
Long-term studies in Amazonia, Africa and central America show that while these botanical behemoths may have adapted successfully to centuries of storms, pests and short-term climatic extremes, they are counterintuitively more vulnerable than other trees to today’s threats.
“Fragmentation of the forests is now disproportionately affecting the big trees,” said William Laurance, a research professor at James Cook University in Cairns, Australia. “Not only do many more trees die near forest edges, but a higher proportion of the trees dying were the big trees.”
“Their tall stature and relatively thick, inflexible trunks, may make them especially prone to uprooting and breakage near forest edges where wind turbulence is increased,” said Laurance in this week’s New Scientist magazine.
Australian blogger and vegetation ecologist Ian Lunt muses about the features that make a forest tick. How important are rain and flames in influencing how ironbark forests function in Southeast Australia? As global warming intensifies, it will be increasingly important to help these forests retain every drop of water they can, he suggests.
Even though my own home forest in the northeastern United States is very different, I was struck by Ian’s lead-in questions: “Which ecological process has the biggest impact on how your ecosystem changes over time?” And: “What if you’re wrong?” Do take the time to read this important think-piece.
Mike at Under the Banyan Tree reports on the seemingly daunting but ultimately encouraging struggle to recover a forest devastated by loggin in Borneo.
The national park managers showed us before and after photographs that revealed how they were slowly turning a wasteland into something that once more resembled a forest. Since 2005, they have planted more than a million trees on 5,000 hectares of the burnt and deforested land. In 2012, they aim to plant trees on another 2,000 hectares.
This is just a start. Because forests like that at Sebangau store vast quantities of carbon below ground in their buried peat and above ground in their trees, they can play an important role in limiting climate change.
It means that efforts to reforest Sebangau could be among the first projects in line for funding under an international scheme called REDD+ that will allow polluting companies and countries to offset their carbon emissions by paying to plant trees and protect forests.
Read the rest of the post to learn how this could help save one of our closest animal cousins from extinction.
The UK blog Save Our Woods features a guest post from the chair of a tenant management organization (TMO) for a housing estate in London. George Arkless finds himself in the awkward position of having to advocate for tree removal, and reflects on the consequences of poor planning for urban trees.
Poor planning, in the residents’ view, means that the problems we now face are numerous, and while anyone from the council we have invited to look at the problems have agreed with us felling trees is such a sensitive matter that no one has been willing to put it in writing.
Just as there is delight when I get out of London and see trees in their true magnificence, or seeing a tree that is alive with life, or a tree so beautiful it just takes your breath away. Why should I need to leave the neighbourhood I live in to see such beauty around me?
The Associated Press today drew our attention to a just-published paper in Biological Conservation: “Trophic cascades in Yellowstone: The first 15 years after wolf reintroduction,” by William J. Ripple and Robert L. Beschta. Since the AP has been known to object to even the briefest unauthorized quotes from their stories, however, screw them. Check out instead the story by Cory Hatch in the Jackson Hole Daily online, “Wolves helping aspens.”
The study was launched in 1997 in an attempt to understand why aspen trees were at the time declining in Yellowstone, said study coauthor William Ripple, an ecology professor at Oregon State University.
“There was no clear scientific answer,” he said. “The topic of predators and wolves was not on my radar.”
After coring aspen trees and counting tree rings, “we found that there was a major decline … starting in the first half of the 20th century,” Ripple said. “Aspen continued its decline all the way up to our study period, in 1997. At that point, we looked at the records. We found that wolves were extirpated early on, and the last wolf was killed in 1926.”
Since wolves were returned in 1995 and ’96, Ripple and his colleagues formed a hypothesis that aspens and other plants would start growing again into tall trees.
Indeed, the percentage of aspen trees browsed in one habitat type — upland areas without logs — dropped from 84 percent to 24 percent from 2006 to 2010. In 97 aspen stands, the mean height of the five tallest trees increased from 60.6 inches to 100.7 inches during the same four years.
And if you’re not too intimidated by ecological jargon, do read the study itself (it’s a PDF).
An eye-opening post from European Trees makes it clear that leaf-blowers are far more than an auditory annoyance.
The threat from existing pathogens and non native invasive species, the threat from climate change factors and the stresses placed upon trees, particularly urban trees by way of human detritus, including domestic pet excrement or urine is compounded by the use of these machines.
Wow. Who knew?