Tom Kimmerer: Arboriculture

Announcing Bluegrass Urban Wood

Wed, 06 Jul 2005 02:41:11 GMT

Our new division, Bluegrass Urban Wood, is now shipping products. We make fine wood products from trees growing in the streets, yards and horse farms of the Bluegrass region of central Kentucky. Presently, we are making flooring from red oak, walnut and other species, with more products to come. Read more about it here.
	Select red oak
	Quarter sawn red oak (vertical grain)
	Street grade red oak

Forget the grass, take care of the trees

Thu, 30 Jun 2005 11:06:30 GMT

Like much of the midwest, Chicago has been suffering from a hot, dry June. Arborists and city authorities there are urging homeowners to water trees but to forget about the grass. Early summer droughts are bad for trees, especially newly planted saplings that lack an adequate root system. By using limited water resources to keep trees healthy, survival and growth in the following years is more likely. Grass can enter a resting state during drought and will recover once cooler wet weather returns. Trees that lose leaves and fine roots in early summer may not fully recover and are more susceptible to future stresses.

Chicago is also deploying fire boats along the waterfront and Chicago River to soak young trees.

Reclaiming wood in paradise

Mon, 20 Jun 2005 19:12:34 GMT

A Hawaiian company is making wood products from trees cut as part of safety programs in Hawaii's Polipoli State Park and Kula Forest Reserve. The company, South Pacific Lumber Co. is providing wood for furniture, millwork and timber framing. The trees are being felled because they pose a risk to cabins and other facilities in the park, but they present a fire hazard if left on the ground. The company has paid $2000 to $3000 to the state to mill 20 pine and cypress trees and will return to mill about 25 more. The fire danger in these forests is very high. Milling the trees prevents fuelwood buildup and provides useful products in a state that lacks available wood resources.

Corps of Engineers plants elms

Mon, 20 Jun 2005 17:20:47 GMT

The US Army Corps of Engineers is planting American elms, Ulmus americana, on a man-made island in the Mississippi River. The Corps planted 21 American elm saplings on Eagle Island to replace other species washed away in a flood. Elms once were a dominant species on Mississippi River bottomlands until they were nearly wiped out by Dutch elm disease. The new saplings come from trees with at least some resistance to the disease. The planting program is part of the US Forest Service American Elm Restoration Project.

Watching for sudden oak death in Georgia

Mon, 20 Jun 2005 17:12:25 GMT

Georgia residents are being asked to watch plants in their yard for signs of disease in an attempt to detect infection with Phytophthora ramorum, the fungus the causes sudden oak death. Special attention is being paid to camellias, lilacs, viburnum, azaleas, rhododendron and mountain-laurel. These plants are known hosts for the fungus, which usually causes leaf spots or twig dieback. The fungus can be fatal to oak trees, and the program is an attempt to eliminate the disease from home gardens before Georgia's valuable and extensive oak forest is infected. Ornamental plants were sent to Georgia from infected Monrovia nurseries in California, so state agriculture authorities suspect that infected plants are in the state. Georgia authorities quarantined plants shipped from Monrovi and other California nurseries, but not until over 49,000 plants had been sold.

Washington D.C. acts to conserve American elms

Sat, 18 Jun 2005 14:13:19 GMT

Scouts in Washington D.C., equipped with handheld computers, are surveying 8.500 American elms, Ulmus americana, on streets and city property. The scouts are looking for symptoms of Dutch elm disease. Trees with symptoms are reported to urban foresters, who then examine the trees further and prescribe treatment if necessary. The city, which once had over 25,000 American elms, has not surveyed trees in several years. With the infusion of funds from Casey Trees, scouting is now possible. American elms can be conserved through a combination of treatment and sanitation, but scouting is the first requirement. The National Park Service has a comprehensive program to preserve elms on Federal property

Scouting beetles in Central Park

Sat, 18 Jun 2005 13:24:24 GMT

National Public Radio has a story by Margot Adler about smoke jumpers climbing trees in and around Central Park looking for Asian longhorned beetle. The story includes vivid descriptions of tree climbing.

Previous story: Smoke Jumpers in Central Park

Adult Asian longhorned beetle, Anoplophora glabripennis. Photo courtesy APHIS, US Department of Agriculture

Stupid city tricks: cutting down fruit trees

Sat, 18 Jun 2005 03:20:52 GMT

The city council of Havering, East London, has allocated funds to replace dozens of fruit-bearing trees along city streets. The trees, including flowering crab and pear trees, will be replaced with trees that don't bear fruit. Why? The council is afraid the city might be sued if trees drop fruit onto pavement (sidewalk or street) and someone slips on the fruit!

Emerald ash borer update: Costs climbing quickly

Sat, 18 Jun 2005 03:02:30 GMT

In the two years since the "EAB" was first found in Ohio, over 200,000 trees have been cut down in an effort to confine the infestation. As we have reported previously, new outbreak areas have been found this year. Ash removal has been paid for by funds from the US Department of Agriculture. As the borer infestation spread, costs may be shifted to land owners. At least 10% of all trees in Ohio are ash trees (of several species). The Ohio state forestry division estimates that if the infestation spreads throughout the state, direct costs for removal could top $1 billion. This does not include the cost of the lost of ash trees in forests, including the timber value and the loss of ecosystem services. Nor does it include the cost of street tree removal by cities or the cost of increased heat loading of city buildings with the loss of shade trees.

In Ann Arbor, Michigan, residents will probably vote in November on a referendum to allocate $4 million for ash removal in the city. This does not include the cost of tree replacement. Timely removal is critical for controlling the spread of "EAB" but also to remove hazardous trees. Ash trees attacked by "EAB" die quickly and become hazardous, with falling dead limbs and entire trees prone to falling.

Some smaller towns are trying to head off the borer by using state and federal funds to replace ash trees before the borer arrives. Bowling Green, Holland, Rossford, Sylvania and Rossville Ohio are removing ash trees and replacing them with species that are not susceptible to "EAB".

"EAB" information can be found at http://www.emeraldashborer.info.

Adult emerald ash borer, Agrilus planipennis. Photo by James Zablotny, US Department of Agriculture

Emerald ash borer update

Wed, 15 Jun 2005 17:23:41 GMT

Roving bug-detection patrols will be scouting southwestern Ontario this summer looking for evidence of "EAB". The inspection areas are mostly outside Essex County and Chatham-Kent, where thousands of trees have been cut to stop the spread of the Asian insect, which is lethal to ash trees. Inspectors will be visiting sawmills, private campgrounds and provincial parks looking for ash firewood that might have been brought in from infested trees. Last year, 22 fines of C$400 were imposed on people who illegally moved firewood out of the quarantined areas. Movement of wood by people is a much greater threat than natural movement of the beetle, since firewood can be hauled over long distance in a short time. Adult beetles have begun emerging in Ontario, and will be colonizing new trees However, the extent of new damage will not be known until fall or spring, after larvae have fed on the tree stems and girdled the trees.

In Ohio, tree climbers have inspected trees in Maumee Bay State Park and found beetle larvae in seven trees. The trees have been removed. Ash trees within 200 yards of the infested trees were girdled to create 'trap trees.' Stressed trees are more attractive to ash borers than unstressed trees. Girdled trees are more attractive to adult beetles than ungirdled trees and trap trees may attract all the emerging adults, preventing them from flying further afield and spreading the infestation. Trap trees will be removed next spring before adult beetles emerge. The effectiveness of this strategy is not known. It is probably less effective than removing all ash trees in the area, but removal budgets are tight.

Adult emerald ash borer, Agrilus planipennis. Photo by James Zablotny, US Department of Agriculture

Tangled Bank

Wed, 15 Jun 2005 16:49:10 GMT

The latest Tangled Bank is up at Geomblog. Tangled Bank is a blog carnival for science writers. The current offering has lots of great articles and is worth a visit.

Nitrogen fertilization decreases abundance of rare and native plants

Mon, 13 Jun 2005 18:01:37 GMT

Rare and native plant species are more likely than abundant or invasive species to be lost from an ecosystem when nitrogen is made more available. Nitrogen increases plant growth, but appears to give a competitive edge to some plants, and a disadvantage to plants that are not adapted to take advantage of more nutrition. This is the conclusion of a wide-ranging nitrogen fertilization experiment by Katherine Suding and her colleagues at UC Irvine. The study was published in PNAS.

Nitrogen in soil comes from nitrogen fixation by certain plants and microorganisms, by lightning-fixation in rainfall, and from manmade sources. The most important manmade sources include fertilizer and acid rain. While fertilizer is not applied intentionally to natural ecosystems, it can arrive in the wind from agricultural sources. Acid rain contains sulfuric and nitric acids from industrial pollution, and is adding considerable amounts of nitrogen to natural ecosystems.

The ecological consequences of nitrogen addition are made clear by this study. Increased nitrogen from anthropogenic sources will reduce biodiversity, eliminate rare species and favor aggressive, fast-growing species including invasives.

As landscaping in urban areas moves toward native plants, it is important to recognize that excess nitrogen fertilization will promote the growth of weeds and non-natives, which have been selected to do well in high-nitrogen environments.

Emerald Ash Borer: conflicts between landowners and state

Mon, 13 Jun 2005 17:04:17 GMT

There are continuing conflicts between property owners and state authorities trying to enforce ash tree removal to prevent spread of "EAB". We have previously reported several stories on these conflicts. In Port Huron, MI, property owners are trying to stave off the ash removal program by treating the trees with systemic pesticides known to deter the beetle. However, the treatments are expensive and need to be repeated annually with no end in site. State authorities have not agreed to permit treated trees to remain. Since the state has no guarantee that the property owner will continue treatment, or that the treatment is 100% effective, authorities are unlikely to permit the trees to stand.

The "EAB" control program requires removal of healthy ash trees within 200 ft. of infested trees (farther in some states). Property owners often do not recognize the need to remove apparently healthy trees. It is a difficult task for agricultural authorities to sell property owners on the need to remove trees, especially prized shade trees, when there is nothing wrong with them. This is a public relations problem for the states trying to prevent spread of the "EAB".

Adult emerald ash borer, Agrilus planipennis. Photo by James Zablotny, US Department of Agriculture

Emerald ash borer extends range in Ohio

Mon, 13 Jun 2005 16:54:26 GMT

The "EAB" has spread in northern Ohio, and is now in downtown Toledo and Maumee Bay State Park. State officials are planning aggressive ash tree removal programs for both areas. The Maumee Bay infestation is particularly worrisome:

"The most disconcerting news for state officials was the discovery of infested trees at Maumee Bay State Park in eastern Lucas County. That means the beetle has moved perilously close to the Lake Erie shoreline and could spread eastward across northern Ohio - something officials have been fighting to avoid. They fear the pest will be much harder to stop if it enters wetland areas in state preserves and the Ottawa National Wildlife Refuge in Ottawa County that have limited road access.

"I can confirm it has been infested," Lee Anne Mizer, agriculture department spokesman, said yesterday of Maumee Bay State Park. She refused to elaborate, indicating the state plans to discuss details on Monday." - Toledo Blade

Adult emerald ash borer, Agrilus planipennis. Photo by James Zablotny, US Department of Agriculture

Winter moths defoliating in New England

Mon, 13 Jun 2005 16:49:13 GMT

The winter moth, Opheroptera brumata, was introduced into North America from Europe. Caterpillars of the winter moth are summer defoliators of maples, apples and blueberries. Long a problem in southern Canada, the winter moth has established itself in Massachusetts and Rhode Island. Winter moth adults emerge in November and December, and many communities in Massachusetts had dense flights of the moths last fall. These areas are now seeing extensive defoliation.

Defoliated trees are weakened somewhat, but spring defoliations are generally followed by a flush of new growth and recovery. Several years of consecutive defoliation can reduce tree vigor, especially if other stressors such as drought also reduce vigor. Defoliation can severely depress fruit production. The winter moth is unlikely to become as serious a problem as the gypsy moth, and effective biological control agents are already known. In Canada, winter moths have been controlled by the introduction of a predatory wasp, Cyzenis albicans, and Massachusetts authorities are raising trial populations of the wasp. It could take several years before wasp populations are high enough to control the winter moth.

The last few years have seen major increases in defoliation from multiple causes in New England. Defoliation by native insects is at all-time high levels. Insect outbreaks are often regulated by weather. Mild winters, such as we have had in recent years, permit higher insect populations to survive. Global warming is thus a likely cause of increased insect infestations.

Dendrophobia in Florida

Mon, 13 Jun 2005 16:21:07 GMT

Florida is facing an outbreak of dendrophobia, the fear of trees, following last years spate of severe hurricanes. Property owners frightened by the amount of damage done by falling trees to roofs, cars, and power lines are removing large trees or heavily pruning them. Combined with extensive construction-related tree removal, the result could be a dramatic reduction in tree cover in Florida's urban forests. Reduced canopy cover, especially in a hot climate, increases the urban heat island effect, creates higher demand for electricity, increases storm water runoff and erosion and damages the esthetic appeal of a city.

The Orlando Sentinel says, in an editorial, that Florida cities need tree management policies and regulations. They propose five policies:

Require permits for tree removal. Orlando and Tampa already require permits but other cities do not;
Identify tree species that should be protected and those whose removal should be encouraged. Alien invasives such as Brazilian peppertree and Australian pine should be targeted for removal;
Pay particular attention to "grand" trees, those well-established trees of significant benefit to the community;
Require government departments to talk with each other to protect trees during right-of-way construction;
Establish crisis response policies to reduce hazards quickly after a storm. This could include lifting permitting requirements for a specified period.

In general, communities need to do more to teach citizens the benefits of trees. Dendrophobia is taking hold in many communities, and the result is a loss in canopy cover throughout a community.

I have been using the term 'dendrophobia' as a way to get people's attention focused on a serious problem. By dendrophobia, I mean the fear of trees described above that leads people to make the apparently rational decision not to have large trees in their lives. However, I recently became aware that dendrophobia is a real psychological disorder, an irrational fear of trees akin to agorophobia or ailurophobia. I probably will continue to use the term in its informal sense.

Flowering hawthorns offend noses

Sun, 12 Jun 2005 17:13:43 GMT

Hawthorns, Crataegus spp., are beautiful small trees suited to urban landscapes. They have showy flowers in early summer and bright red fruits in the fall. Like many trees in the Rosaceae, hawthorn flowers have an offensive smell, sickly sweet with an overtone of burnt rubber. The flowers are attractive to a wide variety of pollinators including bees and beetles.

In Erie, Pennsylvania, hawthorns outside the courthouse are attracting considerable attention because of their odor. Workers in the courthouse and visitors are put off by the strong odors. At first, the source of the odor was attributed to Lake Erie or to a dead animal, but it was the hawthorns.

While hawthorns are beautiful and important landscape trees, perhaps they should not be placed right next to the main door of a public facility.

Homeowners replacing grass with native plants

Sun, 12 Jun 2005 16:42:06 GMT

The suburban sound of lawnmowers is being replaced with the singing of wild birds in many yards. In St. Louis, more and more homeowners are establishing native plant gardens, friendly to birds and other wild animals. Native gardens often require less work than lawn maintenance and are especially suited for shady properties or those with drainage problems. Wild Ones, an organization promoting native plants and natural landscapes has an active chapter in St. Louis and in communities in 10 states in the US. Wild Ones helps promote native plants by holding workshops and member meetings, as well as handbooks and newsletters.

Landscaping has surpassed lawn care in dollar expenditures by homeowners, and the trend toward native gardens is growing rapidly. Arborists, nurseris and landscapers would do well to heed the trend. There are substantial business opportunities in native plant landscaping, and a dearth of expertise and of high-quality plant material.

The trend toward natives should also help accelerate the return of local nursery plant production. This is also a solution to the problem of moving alien pests and pathogens around the country. If homeowners are buying locally-sourced, locally-grown material, the chance of infection by introduced species is reduced.

Thanks to the Invasive Species Weblog for the heads up.

Getting cherry trees to bloom on time

Fri, 10 Jun 2005 17:28:26 GMT

Festivals to celebrate the blooming of trees are held all over the world, and can be a major tourist draw. Most famous among blooming festivals are the various celebrations of cherry blossoms in Japan, Washington DC and other places. The vagaries of weather means that blossoms often fail to appear at the scheduled time for festivities. Since festivals have to be scheduled well in advance, it is easy to miss the actual bloom date. As cities become warmer, both because of climate change and the urban heat island effect, blossoms are occurring much earlier, often well before tourists arrive to celebrate the event.

Authorities in Hirosaki, in northern Japan, are funding research by tree biologists to try to control blossoming so that it occurs when the festivals are scheduled. Since hundreds of thosands of tourists may descend on a properly timed festival, the city stands to lose a lot of money if it is unable to predict the timing of blossoming. Hirosaki is in a cooler area than most Japanese cities and the blossom time of cherries often coincided with Golden Week, a national week of holidays. Up to two million visitors go to Hirosaki when the blossoms coincide with Golden Week.

Scientists at Hirosaki University are experimenting with hormone sprays and injections and piling snow around cherry trees. To date, none of the treatments have been effective. This is not surprising. Once a tree's dormancy requirement has been met, the timing of flowering in temperate trees is tightly tied to degree days (heat accumulation above a threshold temperature). It seems very unlikely that hormonal control of flower timing is significant. Packing snow may cool the roots, but flower development is more likely dependent on air temperature. I suspect that the scientists will spend a lot of money without any significant outcome. Maybe it is time to reschedule Golden Week.

The article describing this issue doesn't address some important questions: how often is Golden Week missed, and has there been a trend toward earlier blooming over time? The article says that there has but does not describe the trend in sufficient detail. Also, the urban heat island effect, which is often much larger in cities than other sources of climate change, is not addressed. While little can be done over the short term regarding climate change, the urban heat island effect can be mitigated.

Los Angeles street tree information

Fri, 10 Jun 2005 16:29:00 GMT

Los Angeles has a great web site for information on its street trees, including permitting and street tree care guidelines. This kind of citizen information could serve as a model for other cities.

Volunteers caring for street trees

Fri, 10 Jun 2005 16:26:18 GMT

In Palo Alto, CA, an innovative volunteer program is improving the health of city trees. Volunteers working with the citizen organization Canopy are taking care of 1200 street trees planted in the last five years. The volunteers are examining the trees for water needs, support stake removal and problems. Problem trees are reported to the city arborist. They are also leaving leaflets with homeowners to remind them to care for the young trees and providing tips on their care. Water needs of young trees are particularly critical in the summer-dry mediterranean climate of coastal California.

While many cities have active tree planting programs, few have the budgets to properly care for the trees. Citizen organizations like Canopy are a great way to mobilize concerned residents to help care for street trees.

Moving giant baobab trees

Fri, 10 Jun 2005 16:05:42 GMT

Moving large ornamental trees is a common arboricultural practice, and often a rather dramatic one. In South Africa, Kruger National Park staff and volunteers had to move two large baobab trees because they were too close to buildings. The trees, one weighing more than 16,000 pounds, were hand dug and lifted onto trucks. The trees were moved to a new park entrance on the Mozambique border, part of an initiative to link parks in South Africa, Mozambique and Zimbabwe.

Baobab, Adansonia spp. and related species, is a genus of bizarre trees with extremely stout stems that store large amounts of water. Folk wisdom says that the baobab was planted upside down by devils or gods.

Wollemi pine going to Japan

Fri, 03 Jun 2005 02:40:14 GMT

Wollemi pine, Wollemia nobilis, an extremely rare Australian species will be planted in Japan in an effort to broaden its range as a hedge against extinction. The tree, known only from the fossil record until 1994, when David Noble discovered living stands in a remote national park near Sydney, will go on sale in Japan next spring. About 500,000 seedlings will be sold to Japanese gardeners. Proceeds from the sale will go to conservation of the native stands in Australia.

Pines are revered in Japan as symbols of long life. Australian conservationists expect Wollemi pine to be extremely popular in Japan.

Wollemi pine should become available as an ornamental tree in other parts of the world, including North America, in 2006. Availability at first will be limited. Wollemi pine is probably hardy to USDA Zone 7 and above, so it is suitable for cultivation in the southern US.

See earlier story.