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Device Determines NIH Tree Health With Minimal Damage
By Carla Garnett
On the Front Page...
When the head of NIH grounds maintenance ran across an article in the local newspaper earlier this year about a "new" tool for tree experts, he had to smile to himself. NIH had been using such a tool with more than fair success for nearly 6 years.
"We saw it at a trade show demonstration in Baltimore back in 1997," recalled Lynn Mueller, chief of the NIH grounds maintenance and landscaping section, Office of Research Services. "Since we do everything we can to save our trees, we were really impressed with how it worked."
The German-made device, called a Resistograph, is roughly the size and shape of a caulking gun and is powered by a hand drill. It takes what amounts to a needle biopsy, leaving a tiny puncture wound in the tree's torso, instead of a big hole. The piercing is self-healing, after a time. What results is a graph printout that resembles the spikes and dips on a heart monitor. A steady period of high spikes indicates a healthy, vital tree; deep valleys on the printout are a sign of inner decay.
"This will get you a look at the inside of the tree without having to cut it," explained William Scofield, the NIH arborist who actually uses the device to reveal whether a tree's wood is sound, rotten in places or completely hollow. "It's also a good tool to give us an indication for possible pruning and for whether a tree is safe and sturdy enough to climb."Healthy Trees Need Not Apply
What typically happens is that "during our leaf-on and leaf-off inspections, we'll identify trees that have visible hazards and indications of inner decay," Mueller explained. "Either that or an employee or one of our maintenance guys will notice something wrong with a tree usually fungus, either on the trunk or on the root flare while he's mowing the grass or doing some trimming. That's when we call on Bill to use this machine. We only use it on trees that appear to be deteriorating in some way. We'll see dead branches, crown dieback or fungus growing, and realize we need to investigate further. We don't need to use it on obviously healthy trees."
A former employee at the National Park Service, Scofield's expertise is the result of years of experience. "It takes about an hour per tree to get an accurate reading," he said, explaining that the needle-width drill bit is inserted twice for each tree, once from north to south and once from east to west. If the prognosis justifies removal, a photo of the tree is taken before and after.
"The maples around here tend to be the weakest," Mueller said. "We've also noticed that the oaks are beginning to act up, mainly because of soil compaction and many of them were planted in too-narrow spaces, which limits their lifespan."
Nevertheless, Mueller said, sometimes despite efforts to treat or cure it, a tree has to come down before it falls down and hurts someone or damages property. "Sometimes," he concluded, "we'll leave what's called a 'snag.' That's one of those tall trunks you might see left standing. We do that out of consideration for wildlife that may be still using the tree. In all cases we preserve as much as possible. Using the [Resistograph] helps us without harming the tree."Flourishes about NIH Flora and Fauna
Another of NIH's trees was recently named a Champion Tree by the Montgomery County Forestry Board. A weeping willow that lives along the creek-bed at the corner of Cedar Lane and Rockville Pike was determined to be the largest tree of its species (salix) in the county. The willow, #2330 on NIH's tree survey, is NIH's sixth winning tree and second champion willow species since 1999. "What's amazing about this champion tree," noted Mueller, "is that it was planted in 1968."
Soon, unfortunately, a one-of-its-kind tree at NIH will have to be taken down to make space for construction related to the new Bldg. 33, which will be erected on what is now parking lot 31F. Tagged #2398, the 17-inch caliper yellow buckeye, the only one of its type on the NIH grounds, will be replaced by three NIH-propagated baby yellow buckeyes in the same vicinity. The new trees will be planted out of future harm's way, Mueller said.
NIH is also planting more trees in the largest wooded area on campus, the Cedar Lane Woods located between the Children's Inn and the new NIH firehouse near Old Georgetown Rd. According to Mueller, there must be 100 trees per acre for a parcel of land to be cited as a forest by the Maryland department of forestry.
"We're repopulating that area in an attempt to get the forest designation," he said. "We're real close, but not there quite yet. It'll take us a few more years of planting young native tree species to reach that designation."
In other news of NIH flora and fauna, Mueller reports that about 17,000 annual flowers, impatiens, petunias and vinca will be planted on the grounds this spring.
"Our guys have about 6 weeks between the last frost and the summer heat to get them all out," he said.
Also, six additional bluebird houses have been erected on campus. The structures are monitored weekly for habitation on the northern portion of campus by employee volunteers Cindy Clark and Theresa Sartori, and along the southern half by retired neighbor Jim Gardner. This is the third straight year of the project that aims to reduce NIH's summer insect population without using pesticides. The effort has been a huge success that is popular with employees as well as neighbors. Last year, 88 fledglings were seen checking out of the NIH accommodations, with 17 bluebird babies among those housed. Also recorded were house wrens, chickadees and tree swallows.
"The bird box monitoring project has allowed us to learn more about the species that frequent the NIH Bethesda campus, including their habitats and behaviors," said Clark, who along with Sartori is a biomedical librarian in the information and education services section of the NIH Library in Bldg. 10. "This is fun and quite exciting when we encounter a new resident. We keep statistics on the number and species of birds fledged from each box each year. We have also gained an appreciation of the efforts that Lynn Mueller and grounds maintenance people make to both the beauty and the health of the campus environment."
Mueller also reported that two purple martin houses erected in March at the NIH Animal Center in Poolesville have already been occupied by new colonies.
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