Trees In Towns Research Articles

Technical and economic analysis of Stone pine (Pinus pinea L.) maintenance in urban areas

The Italian Stone pine (Pinus pinea L.) is one of the most common ornamental trees in towns with Mediterranean climates. For example, in the city of Rome (Italy), Pinus is the most common genus, with more than 51,000 trees. This study investigates technical and economic features of maintenance operations of Stone pines and evaluates the productivity and costs of the observed work sites. Pruning and felling are the most frequent management operations of trees in towns and this study analyzes the features of these operations carried out in 17 work sites. The operations were carried out either with aerial platforms (20 trees) or ascending the crown by tree-climbing (8 trees). The operations were sampled with time studies (12 trees for pruning and 16 for felling). Work time was measured from the beginning of operations to the transport of the residual biomass to the collection and loading point, using centesimal stopwatches and video recording. The total residual biomass was weighed or assessed. Total observation time amounted to 84.1 h. Cost calculation for each site considered the fixed and the variable costs and the costs for the labor force. Multiple Linear Regression models which utilize regressors easily evaluable before the work, were adopted to predict the gross time of the operations and the cost per tree. This paper can contribute to optimize tree maintenance methods in urban sites and to assess the potential residual wood biomass attainable from urban forestry maintenance in the city of Rome.

First records of the sycamore lace bug, Corythucha ciliata (Say), in Greece

In late August 1988, the author noticed the presence of Corythucha ciliata (Say) (Hemiptera: Tingidae) in many plane trees of the following locations of northwestern Greece: 1) City of Kastoria, on 22.VIII.1988, along the coastal road of the city’s peninsula in Lake Orestias. Along this road, trees near the Panaghia Mavriotissa church were heavily infested, while trees further away were less so. Infested trees were also noticed along the quay of the northern end of the city. 2) Zagori, Epirus, on 24. VIII.1988, on the banks of the river Voidomatis, where the river meets the road between the villages Aristi and Papingo. The degree of infestation varied between adjacent trees. 3) Zagori, Epirus, on 25.VIII.1988, the single plane tree in the middle of the square of the village Eptahori. 4) City of Yannina, on 26. VIII. 1988, several single trees in the Kastro section of the city and also trees along the banks of the lake bordering the city. As heavily infested were recorded trees having most of their leaves chlorotic in the largest part of their laminae. On the underside of leaves that could be reached from the ground live adults, exuviae of immature stages and dark sports typical of excrement and of oviposition sites of Tingidae were found. On certain leaves more than 10 live adults per leaf were counted in Kastoria and Yannina. The identity of the species was determined by the author on adult specimens from Kastoria preserved dry and in ethanol. The fact that the infested locations were tens of kilometers apart and at considerably differ ent altitudes, leads to the conclusion that C. ciliata must have crossed the Greek northwest­ern border not less than two years ago. It is suspected that the insect entered Greece by natural spread from neighboring Albania. Examination by the author of plane trees in towns and villages of the Pella and Kilkis prefectures near the Yugoslavian border, showed no infestation. C. ciliata is of nearctic origin. In the northeastern and northwestern United States it is a pest of sycamore, Platanus occidentalis L., which is its preferred host plant, but also feeds on ash, hickory and also on mulberry. In Europe the host plants of preference are Platanus X acerifolia (Afton) Willd. and P. orientalis L., while such other broad-leaved trees as Brussonetia pap•rifera and ash are also reported as able to support the insect. The insect entered Europe and was noted first in Italy in 1964. Its spread was rather rapid, so that by 1986 it had spread to all the regions of Italy. In 1976 chemical control tests against it were re­ported from Hungary. Its presence in Yugoslavia was reported in 1972, in France in 1977, in Spain in 1981, in Switzerland in 1983 and in Austria in 1984. It is considered one of the three most important insects infesting the leaves of plane trees in Italy and generally very destructive. The adult insect is approximately 3 to 3.5 mm long and has reticulate front wings and reticulate expansions of the pronotum. The pronotum is yellowish, largely expanded on the sides which are transparent, and has a median vesicated process. The front wings are subquadrangular and have a proximal vesica which is globular and more or less smoky to­wards its internal margin. Two to three generations per year have been reported in Italy, same as in the northeastern United States. Hibernation takes place in the adult stage, mostly under loose bark at the basal part of the trunk or in other protected places nearby. In spring, the adults move to the young leaves, where they lay their eggs on the under side of the blade where the immature stages feed and develop and the long-lived adults re­main feeding and reproducing. The feeding punctures cause chlorosis which starts from the basal part of the leaf and may expand to almost the whole leaf. On the underside of leaves, where the insect lives in colonies, there are usually numerous small dark spots. Heavily infested species of Platanus, in addition to extensive yellowing, may undergo premature leaf drop. In Italy and especially in urban areas, C. ciliata continues to cause concern because of the weakening of plane trees which predis­poses them to attacks by other enemies. There is no doubt that the spread of C. ciliates in Greece will also be fairly rapid. The authorities should take advantage of the extensive work done in Italy, to further develop effective and ecologically sound control measures. Determining the resistance to the insect of Plalanus stock available in Greece should be among the projects to be encouraged.

The Urban Forest and Ecosystem Services: Impacts on Urban Water, Heat, and Pollution Cycles at the Tree, Street, and City Scale.

Many environmental challenges are exacerbated within the urban landscape, such as stormwater runoff and flood risk, chemical and particulate pollution of urban air, soil and water, the urban heat island, and summer heat waves. Urban trees, and the urban forest as a whole, can be managed to have an impact on the urban water, heat, carbon and pollution cycles. However, there is an increasing need for empirical evidence as to the magnitude of the impacts, both beneficial and adverse, that urban trees can provide and the role that climatic region and built landscape circumstance play in modifying those impacts. This special section presents new research that advances our knowledge of the ecological and environmental services provided by the urban forest. The 14 studies included provide a global perspective on the role of trees in towns and cities from five continents. Some studies provide evidence for the cooling benefit of the local microclimate in urban green space with and without trees. Other studies focus solely on the cooling benefit of urban tree transpiration at a mesoscale or on cooling from canopy shade at a street and pedestrian scale. Other studies are concerned with tree species differences in canopy interception of rainfall, water uptake from biofilter systems, and water quality improvements through nutrient uptake from stormwater runoff. Research reported here also considers both the positive and the negative impacts of trees on air quality, through the role of trees in removing air pollutants such as ozone as well as in releasing potentially harmful volatile organic compounds and allergenic particulates. A transdisciplinary framework to support future urban forest research is proposed to better understand and communicate the role of urban trees in urban biogeochemical cycles that are highly disturbed, highly managed, and of paramount importance to human health and well-being.

Apology

Apology Brad Watson (bio) Click for larger view View full resolution © Jane Molinary I’VE BEEN HERE IN THE DESERT, in this little town, for two months now. I don’t know if you would like it out here on the high southwestern plains but I suspect not. Such windblown open spaces. The trees in town give way to endless arid prairie. The constant passage of long, loud trains, busy, muscular, saddening. I know our little boy would like that, at least. The trains. [End Page 84] Yesterday, along the tracks west of town, the Union Pacific boomed down with five engines and three hundred double-stacked cars. Six hundred cars, if a piggyback is two. You can believe that or not. The mares and foals were gone from their pasture. Eight large crows flew from the cistern there, silent, blown by the southwest gray-blue wind. A pronghorn stood alone on the hill, just inside the barbed wire fence, alert and anxious, making that strange call they make. Like a wind-up party favor, or the stripped gears of a lawnmower crank yanked hard and whirring sharp and short. A cough from rusting metal lungs. Farther down, on the tracks’ north side, another pronghorn sprawled out dead in a dusty two-track road, eyes and tongue hollowed, devoured by flies, still swarming. Something had yanked his colon out and left it two feet from the carcass, the round cavity beneath his tail empty and wet with bright fresh blood. A strange mutilation. No obvious sign he was hit by the train, or shot, or chased and torn apart by lion or coyote or some extraordinarily numerous murder of crows. Only the bloody colon, and the coat along each side of his spine roughly shorn, as if grazed by the sharp front teeth of his own kind. Pronghorn, jackrabbit, horses, crows. Trains, clouds, the occasional car. You rarely see people if you don’t go downtown. Which is good. I SPEND ALL MY TIME at this house I occupy up on the hill, or walking the trail out into the desert along the railroad tracks, or at the liquor store or grocery store, or drunk and wandering one of the desolate dirt tracks spurring from town into the prairie. All else is gone, like the pronghorn, like the little bird I will tell you about, like my former ambition, which now seems to have been tied far too closely to a lack of imagination, so, gone. I did make a friend, Marie, who works in the coffee shop in town. This is not her great ambition. Like a lot of people here, she’s lying low for a while. She does occasional favors for the movie people who are in town making, of course, a movie. The regular movie people live in the motel. The big shots and stars rent estates and have their personal assistants plus special assistants who live in this town. Marie is sometimes one of those. In fact, we met when I went into the coffee shop where Marie works, and she mistook me for a movie person because I was a new face in town. We laughed about that and I got a free coffee. Should I have been flattered to be mistaken for a movie person, or is it just that movie people, everyone except the most famous or the prettiest actors, look like ordinary people out of their element? Marie even has a sense of humor, in her own way, about her cancer. She still calls it her cancer even though it’s officially gone. She says it’s like a bad [End Page 85] boyfriend—you never know when he might show up again, asleep or passed out there, in the backyard, but alive. I went over to her house for dinner, and she didn’t mind talking about her cancer, or her boyfriend who had a harder time with her cancer than she did, or how long she will stay here before going back to civilization, which for her is California, and how nice it was to spend time with a man (me) without all that shit going on. Infatuation, sex...

A broad scale analysis of tree risk, mitigation and potential habitat for cavity-nesting birds

Trees in towns and cities provide habitat for wildlife. In particular, cavity-nesting birds nest in the dead and decayed stems and branches of these trees. The same dead and decayed stems and branches also have a greater likelihood of failure, which, in some circumstances, increases risk. We examined 1760 trees in Baltimore, MD, USA and western MA, USA, assessing tree risk and, for a sub-sample, noting the presence of cavity nests excavated by birds. In Baltimore, most trees were in areas of frequent use and had no visible defects. In western MA, most trees were in areas of infrequent use and 70% had visible defects. The most common defect in both locations was dead branches and stubs between 10 and 51cm in diameter. Trees with a cavity nest had a greater likelihood of failure than trees without a cavity nest. Our data provide an overview of tree risk assessment and mitigation, a baseline understanding of risk parameters for common street trees in the Northeast and Mid-Atlantic regions of the United States, and insight into whether a balance can be struck between tree risk and provision of wildlife habitat.

TREES IN TOWNS II AND THE CONTRIBUTION OF ARBORICULTURE

In February 2008, the Department for Communities and Local Government published its long awaited report on urban trees in England entitled Trees in Towns II. The report assesses the urban tree population in England as well as identifying the policies and practice of urban tree management by English local authorities. This paper highlights the significance of this government report for the arboricultural industry. It also stresses the report's relevance to the growing debate about the importance of green infrastructure, sustainable cities and urban climate adaptation. Lastly, it explores the potential contribution of the arboricultural industry to achieving the aims of Trees in Towns II and the promotion of green infrastructure and sustainable cities.

Pileated Woodpeckers, <em>Dryocopus pileatus</em>, Foraging in Suburban Habitats in New Brunswick

Pileated Woodpeckers (Dryocopus pileatus), usually woodland birds, were seen often in Sackville, New Brunswick, in winters 2005-2007. Excavations in trees were made mostly by two female birds. A male bird joined each female briefly in late winter. These birds probably all roosted in wooded areas west of town. Most large trees in town are broad-leafed, in contrast to the mostly conifer woods to the west (there are only open lands to the east). Feeding excavations in town were mostly in maples, with little use of elms. Prey noted were large larvae, seemingly of sawflies, unlike published reports of Pileated Woodpecker feeding mainly on adult ants and beetles. Excavations further weakened trees already damaged by boring insects, causing perceived risks to passers-by and to overhead wires. Work by woodpeckers alerted arborists to weakened trees or branches, many of which were removed. Local people were excited at seeing, close up, these impressive – and tame – birds.

Fireblight in Békés County (Hungary) in 1996/20021

Fireblight (Erwinia amylovora) appeared in Hungary in 1996. Most damage occurred on apple, pear, quince and medlar, and also on the ornamentals Pyracantha, Sorbus, Cotoneaster and Crataegus. In 1996–2006, an official programme for elimination of infected parts of plants started in Békés county. This mainly concerned trees in towns and villages, since there are few pome‐fruit orchards in the county. Work teams under official direction pruned back or cut down trees. In total, some 13 000 trees were pruned back and nearly 11 000 were cut down. In addition, 21 villages were subjected to special phytosanitary measures. Infection decreased considerably between 1996 and 2002, but over 90% of the inhabited areas in the county remained subject to special measures, because of the very dispersed occurrence of fireblight.

Urban woodlands: their role in reducing the effects of particulate pollution

In recent years a substantial research effort has focused on the links between particulate air pollution and poor health. As a result the PM 10 value has been set as a measure of such pollutants which can directly cause illness. Due to their large leaf areas relative to the ground on which they stand and the physical properties of their surfaces, trees can act as biological filters, removing large numbers of airborne particles and hence improving the quality of air in polluted environments. The role of vegetation and urban woodlands in reducing the effects of particulate pollution is reviewed here. The improvement of urban air quality achieved by establishing more trees in towns and cities is also illustrated.

Variations of trace element concentrations in red spruce tree rings

The potential of coniferous trees as biological indicators of heavy metal atmospheric pollution was investigated. In 31 municipalities of an industrialized region, samples of wood from the trunks of red spruce (Picea rubens) were taken to determine the spatial distribution of accumulated metals. Using the annual rings, these core samples were divided into 5-yr sections to determine temporal variations. The concentrations of Mg, Al, Ca, Mn, Fe, Cu, and Zn were measured by neutron activation analysis. All metals showed the highest concentrations in the most recent wood and the bark. For the wood older than 5 yr, Mn and Zn are stable with time, Mg and Ca decrease, while Al, Fe, and Cu appear to increase. A statistical analysis showed the municipalities with the highest variations in metal concentrations; it also revealed correlations in the fluctuations of several of the metals. As expected, trees in towns near metal refineries contain higher amounts of Mn, Fe, and Al. Large variations in metal concentrations, due to factors not totally understood, were observed. Thus, red spruce is not a sensitive bio-indicator of atmospheric metal pollution.

THE PLACE OF TREES IN TOWNS: A PLANNER'S VIEW

Summary Because trees are counter elements to buildings, planners like to include them in drawings, plans and proposals for new developments. The pace of recent urban built environmental change has also accorded trees a special place as a link with the countryside. Conservation of these natural elements is now a recognised planning policy and tree preservation orders reflect this concern. However, whilst planners are familiar with the town as a social entity, they remain generally unaware of the life cycle of the tree. Urban forestry could well provide a structured context for a better appreciation by planners and others of the place of trees in towns.

TREES IN TOWNS AND THEIR EVALUATION

TREES IN TOWNS AND THEIR EVALUATION

The Pruning of Trees in Towns

THE services of Prof. Bayley Balfour, F.R.S., have been obtained by H.M. Office of Works to inquire into the justness or otherwise of complaints made in regard to the treatment of the young trees in the Mall. His report, which has just been issued from the Stationery Office (Cd. 5823, price 21/2d.), must be gratifying to those who have charge of the trees, for he finds nothing to justify adverse criticism of the pruning. On the contrary, he was impressed by the evidence of sound practical knowledge and scientific principle shown in their treatment. It was high time that someone in a position of authority should have been called on to lay down the principles that govern, or should govern, the pruning of trees in public thoroughfares. The outcry periodically made in the daily Press is usually marked by want of knowledge and unfairness. As a matter of fact, there is no work more thankless in nature than the management of street trees. In London and other great urban areas the planter's choice is restricted to a few species (of which the plane is the chief and best) which experience has proved will thrive, but which, as regards size, are quite unsuited to the spaces usually available for them. In the Mall this difficulty does not arise, for the space is ample. The object there is to control the growth of the trees that have been planted so that the foundations of a stately avenue may be laid.