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| To advance the science of arboriculture for the public benefit |
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| To advance the science of arboriculture for the public benefit |
The Arboricultural Journal
The Arboricultural Journal is published quarterly and issued free to members of the Arboricultural Association. It contains valuable technical, research and scientific information about all aspects of arboriculture. The Arboricultural Journal is edited by an editorial board of 14 eminent professionals from 8 different countries.
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AN EVALUATION OF RESIDENTS' ATTITUDES TO STREET TREES IN SOUTHWEST ENGLAND
John Flannigan
Summary
The majority of research into attitudes to street trees close to residents' homes has been undertaken in the USA, where a generally positive attitude towards such trees exists. Limited UK research thus far suggests less positive attitudes to street trees, which is reinforced by anecdotal reports from professional Arboriculturists who describe negative opinions by residents to nearby trees. Residents from three case study areas in southwest England were questioned about their attitudes to nearby street trees using the survey method developed by North American researchers (SOMMER et al., 1989; SCHROEDER and RUFFOLO, 1996). The survey assessed residents' overall opinion of the trees, attitude to pruning regimes and the Council's maintenance, satisfaction with the benefits and annoyance they receive from the trees, the trees' size, shape, and growth rate. Two case studies considered regularly pollarded street trees and one case study used non-pollarded trees. Residents had a generally good overall opinion of the tree near their home irrespective of tree type, rating visual attractiveness as the highest benefit and raking fallen leaves in autumn as the most annoying feature. Annoyances were rated less highly overall than benefits. Demographic factors appeared to have little influence on attitudes to trees although evidence was collected that found when physical ability is negatively affected by age overall opinion of nearby street trees reduces. No resident reported that the tree outside their home was too small or grew too slowly, suggesting that residents preferred smaller trees.
Keywords:
Street trees · benefits · annoyances · residents' perceptions · pollarded trees · tree size
PROPAGATION OF TREES OF COMMON LIME (TILIA X EUROPAEA L.) PLANTED IN SWEDISH GARDENS IN THE 17TH AND 18TH CENTURIES
Rune Bengtsson*
Summary
Trees of common lime (Tilia x europaea L.) were very common in parks and gardens of the 17th and 18th centuries in Sweden and in other countries in central and northern Europe. Due to the longevity of lime trees and their ability to endure pruning, many of those trees still remain although they are often in need of restoration or replacement. Before such measures are taken, the taxonomy should be investigated. The lime trees planted in Swedish gardens during this period are, with very few exceptions, of common lime (Tilia x europaea L.) but there is considerable variation within this taxon. To understand this variation it is necessary to know how the trees were propagated. Based on studies of historical and contemporary references and field studies, it was possible to conclude that the majority of lime trees planted in Sweden during the 17th and 18th centuries were vegetatively propagated by layering. During the second half of the 18th century, seed-propagated trees were also used. The more effective method of propagation by seed may have been prevented for most of the period by inferior seed quality due to the climatic conditions referred to as the 'little ice age' (ca. 1430-1850).
Keywords:
clones · gardens · layering · restoration · seed propagation
LANDFILL LEACHATE NUTRIENT RECOVERY BY WILLOW SHORT ROTATION COPPICE III. SOIL WATER QUALITY
Andrew Godley, Gillian Alker, John Hallett, Richard Marshall and Drusilla Riddell-Black
Summary
The treatment of landfill leachate with Short Rotation Coppice (SRC) is reliant on both the plant and soil of the system (GODLEY et al., 2004a and b). In summer there is virtually no drainage of water from the soil and moisture losses are almost exclusively from evapotranspiration. This means that there is the potential for contaminants in applied leachate to become concentrated in the soil. During winter, plant dormancy and rainfall infiltration means that water losses from drainage of the soil will be maximised and soil microbes will play the major role in treatment. Therefore in winter contaminants accumulated during summer leachate applications may be removed from the soil by drainage. Low soil temperatures and water-saturated soils in winter may reduce the rate of aerobic microbial activity. Consequently leachate applications in winter need to consider contaminant losses from drainage and reduced microbial activity in order to avoid increasing the concentration of contaminants in soil pore water further. In particular the concentrations of nitrogen compounds and chloride in landfill leachate have the potential to encourage leaching of these components. This paper describes an investigation of the soil pore water quality following irrigation with landfill leachate at the Hatfield willow SRC trial (GODLEY et al., 2004a and b).
Over the duration of the trial, the water input to leachate irrigated plots was dominated by rainwater (89% of the total water input). This diluted the dissolved leachate components discharged from the plantation to considerably lower levels than found in the leachate. The nitrate emissions from drainage water were low and did not impact nitrate concentrations in an on-site ditch and would have had little impact on effluents discharged from the site at the site boundary. Chloride and nitrate-nitrogen concentrations were higher in 2001/2002 than the 2 proceeding years in response higher loading levels.
Applications of leachate had little effect on the soil pore water, drain or ditch concentrations of potassium, magnesium, sodium, ammonium-nitrogen, calcium, chemical oxygen demand, total organic carbon, and Boron.
DIMENSIONING OF TREE CONTAINERS WITHOUT WINDLOAD ASSESSMENT
C. Mattheck, I. Tesari and K. Bethge
Summary
Planting trees in containers can remove the problems of the interaction of roots with man-made structures in close proximity. However they can fail by wind throw. This short paper presents an approximation to calculate the size of the container radius required for stability from the failure moment of the tree trunk. The equation can also be used to estimate the point at which transplanting the tree into a bigger container should be considered.
THE NON-NATIVE INVASIVE PHELLODENDRON AMURENSE RUPR. IN A NEW YORK CITY WOODLAND
Carsten W. Glaeser1 and Dwight Kincaid²
Summary
A quantitative census of woody taxa ³ 2.0 cm diameter breast height (DBH) was performed within a contiguous 0.5 ha plot in a 167 ha wooded area of the 217 ha Forest Park in Queens County of New York City, USA. The census revealed a highly abundant non-native invasive tree, Amur corktree (Phellodendron amurense Rupr., Rutaceae) with no previous reporting on its ecology in NYC since its horticultural introduction to the park in 1935. The corktree is a dioecious, deciduous, compound leafed tree with deeply fissured corky bark and is native to Northern China, Korea and Japan. It is reported as shade-intolerant in Japan yet is shade-tolerant in this study of a New York City woodland. This study documents its movement into the canopy and up the ecological dominance hierarchy. Of the 22 sampled taxa (n = 771 trees), P. amurense ranked third in overall dominance behind Betula lenta and Quercus rubra with an importance value (IV) of 33.3%. At 20.5%,
P. amurense ranked second in relative abundance with Betula lenta, the most abundant at 28.1%. Stem density for P. amurense was 316 stems ha-1 with a summed basal area that accounted for 2.9% of the total basal area, which was consistent with its small diameter size (4.76 cm mean DBH, SD 3.69). For tree height, 63.2% of the population of corktrees are<6.0 m (4.90 m mean height, SD 2.08) and the maximum height measured 11.7 m. Bootstrap 95% confidence intervals of the observed 20.5% relative density suggest that parametric relative density of the corktree, across the larger woodland may range from a low 11.9% to a high 31.0% of trees. Its 95% confidence intervals for IV were found to overlap with those of Quercus rubra, Cornus florida and Q. velutina suggesting a corktree's inferential ecological dominance ranking lies from an IV rank of 2 to 5.
DEVELOPMENT OF DECAY IN THE SAPWOOD OF TREES WOUNDED BY THE USE OF DECAY DETECTING DEVICES
W. Kersten and F.W.M.R. Schwarze
Summary
The effects of drilling holes with the IML-Resistograph and an increment borer were examined in London plane Platanus x hispanica Muench. and ash Fraxinus excelsior L. trees naturally infected with Inonotus hispidus. Eight months after inflicting the wounds on the lower stem, trees were felled and dissected. Microorganisms were isolated in pure culture and identified from the decayed wood, host-fungus interface, discoloured wood and the sapwood. In both hosts the extent of discoloration and decay within the sapwood and also the frequency of isolation of I. hispidus from these altered zones were greater after wounding with the IML-Resistograph than with the increment borer. These differences may be related to micro-environmental conditions. Tightly packed wood shavings are retained within the IML-Resistograph drill holes, whereas the holes created with the increment borer remain open, allowing ingress of air into the sapwood. Such alterations in growth conditions seem to be unfavourable for growth of Inonotus hispidus, which reacted by forming mycelial plugs that firmly sealed each of the increment borer holes. As mycelial plugs were never observed in wounds induced with the IML-Resistograph, it appears possible that pre-existing conditions are not greatly modified and that the fungus can therefore grow out into the adjacent sapwood more readily. Additional laboratory studies on a naturally infected beech (Fagus sylvatica L.) and ash showed that cross-infection via drills contaminated with fungal propagules appears unlikely.
THE POTENTIAL FOR BIOSOLIDS AS SOIL CONDITIONERS AND FERTILISERS IN ARBORICULTURE
S.R. Smith*, R. Morris*, T. Breedon*, D.M. Bellett-Travers**,
Summary
Biosolids are used extensively as effective soil conditioners and organic fertilisers in both farming and reclamation of ex?industrial and brownfield sites. However, there has been little attempt to introduce biosolids into amenity horticultural practices. A field trial with Betula pendula Roth. (Silver Birch) carried out at the Imperial College London Field Centre, Silwood Park, Ascot has demonstrated the nutrient value and soil conditioning properties of biosolids to trees. In addition to organic matter, they also provide substantial amounts of plant available nitrogen (N), phosphate (P), sulphur (S) and micronutrients. Composted biosolids also contain significant amounts of potassium (K).
Enhanced treated biosolids have potential for application to areas where there is significant public activity, as these biosolids are treated to destroy microbial pathogens. Conventionally treated materials may be used with land application and restrictions exist for this type of sludge product to control pathogen risks. Horticultural operatives in the amenity market have a preference for composted products or granules produced by thermally drying sludge because these materials are easy to handle.
A CRITIC OF THE STATIC INTEGRATED ANALYSIS (SIA) METHOD
C. Mattheck* and K. Bethge*
Summary
This report details a critical assessment of the Static Integrated Analysis SIA-method by the authors based on literature. The SIA-method (Wessolly and Erb, 1998) considers only four different shapes for the tree crown, which do not exist in cities showing such a low branch attachment. According to SIA, all trees in cities have the same wind load that is calculated based on a "proposal" for the drag coefficient. Required stem diameters and minimum wall thickness in hollow trees are derived from height measurements using bending theory. The effect of longitudinal shear cracks and cracks related to water hose kinking appear to be neglected in the SIA-method.
For this reason, trees assessed by the SIA-method are theoretically allowed to be much more hollow than trees assessed by Visual Tree Assessment VTA-method, substantiated on extensive field studies performed for the VTA-failure criterion.
The SIA-method is described by WESSOLLY and ERB (1998). It is surprising that SIA is actually the end of a tree assessment, i.e. the evaluation of the risk by failure criteria. The method does not include a catalogue of defect symptoms (warning signals in the body language of trees) as it is offered in VTA (MATTHECK and BRELOER, 1994). SIA tries to calculate maximum possible H/D-ratios and minimum wall thickness (hollow trees).
This paper describes the process of the SIA-method based on our current knowledge and understanding.
In WESSOLLY and ERB (1998) only the formal procedure is given. The reader is guided from diagram to diagram without pointing out the background of the theory.
DETECTION OF DECAY IN TREES WITH STRESS WAVES AND INTERPRETATION OF ACOUSTIC TOMOGRAMS
C. Rabe,1 D. Ferner1, S. Fink1 and F.W.M.R. Schwarze,1,2
Summary
Cross-sectional maps of stems of beech, Horse chesnut and Norway maple affected by Ganoderma adspersum (Schulz) Donk, Pleurotus ostreatus (Jaquin: Fr.) Kumm and Kretzschmaria deusta (Hoffm.: P. Martin) (= Ustulina deusta (Fr.) Petrak), respectively showing fungal decay were obtained from living trees. Zones of altered fresh- and dry-matter density were constructed, and these compared with Picus® acoustic tomograms of the same cross-sections. The studies shown demonstrate that within a sample cross-section, a zone of decay can be determined accurately for its size and moderately accurately for its position. The shape of the sample cross section influences the accuracy of the acoustic tomograms. Thus the greater the deviation from a circular outline, the poorer the accuracy. Likewise, the number of sensors naturally affects the accuracy. Wood decay caused by Kretzschmaria deusta can be detected by the Picus® acoustic tomograph. The resolution of the tomograms is still worthy of improvement as reaction zones cannot yet be represented, despite their high density. Although capable of improvement in some respects, the Picus® acoustic tomograph currently offers a very good diagnostic support for evaluating the condition of trees and hence their resistance to fracture..
REVIEWING TREE PRESERVATION ORDERS: IMPLICATIONS FOR LOCAL PLANNING AUTHORITIES
Ann Currell*
Summary
Tree Preservation Orders (TPOs) have served to protect trees since their introduction in the Town and Country Planning Act 1947. Subsequent amendments to legislation has resulted in a variety of anomalies and discrepancies between TPOs. Hence, local planning authorities (LPAs) are advised to keep their TPOs under review (DETR, 2000). To investigate aspects of the TPO review process a series of questionnaires and interviews were conducted with LPAs, Central Government and the London Tree Officers Association (LTOA). Sixty one LPAs completed initial questionnaires of which 32 were reviewing TPOs and 29 were not.
The main factors affecting current practice were the enforceability, workability and accuracy of existing TPOs. Staffing levels available to undertake a review were also a major factor. These factors also influenced the review procedure and timing of review, however, review was more likely to take place when Council Members were actively involved in the procedure.
The consequences of not updating TPOs were to have fewer TPOs that were less accurate and less easily enforced. The potential to use Article 5 Certificates might be a disincentive to reviewing TPOs.
Without government prioritisation, LPAs will determine their own priorities. Many LPAs are not resourcing TPO reviews and the lack of enforceability of many TPOs will leave trees unprotected.
LANDFILL LEACHATE NUTRIENT RECOVERY BY WILLOW SHORT ROTATION COPPICE II. SOIL QUALITY
Andrew Godley*, Gillian Alker*, John Hallett*, Richard Marshall** and Drusilla Riddell-Black***
Summary
The application of landfill leachate to willow short rotation coppice (SRC) has been shown to enhance the growth of the crop and has lead to substantial offtakes of constituent chemical components (GODLEY et al., 2004). Despite the attenuation of leachate by crop growth there is potential for soil contamination in particular from sodium (Na) and chloride (Cl) constituents. A study of the soil chemical conditions at the Hatfield trial site (GODLEY et al., 2004) demonstrated that while there were significant increases in soil Cl and Na concentrations following leachate application, the effects were short lived and winter leaching from the soil returned levels similar to those of the control plots after 7 months without leachate irrigation.
The Hatfield willow SRC trial showed that there were no significant effects (P > 0.05) from leachate application on the soil concentrations of total calcium, total magnesium, total phosphorus, cadmium, chromium, copper, mercury, nickel, lead and zinc. Additions of these components were negligible compared to the mass already present in the soil, therefore it was unlikely that leachate application would have sig-nificantly changed their soil concentration.
Ammonium-nitrogen (NH4-N) was similarly unaffected by leachate applications, however elevated soil nitrate-N (NO3-N) contents in leachate treated soil indicated that nitrification processes convert a proportion of the NH4-N applied to NO3-N. Leachate irrigation raised the plant available K, Mg and B contents of the soil by a small amount but levels remained within the ranges of crop nutrient status.
IMPACT AND MANAGEMENT OF THE HORSE CHESTNUT LEAF-MINER (CAMERARIA OHRIDELLA)
N.A. Straw* and M. Bellett-Travers**
Summary
The horse chestnut leaf-miner (Cameraria ohridella Deschka & Dimic) is a new pest of horse chestnut that established in the UK in 2002. Experience from Europe indicates that where the moth has become established, it will cause severe damage to the foliage of horse chestnut on an annual basis, and defoliation before normal leaf-fall in the autumn. However, it appears that most damage caused by C. ohridella occurs too late in the season to have a major impact on the vitality of horse chestnut. There is no evidence from Europe that trees have died, or shown a progressive decline in health, as a direct consequence of C. ohridella attack. Nevertheless, there are advantages in implementing controls to reduce infestation. Any reduction in damage, especially in built-up areas, will help to maintain tree health and ensure survival, and this could be more important in the UK, because of differences in climate and interactions with other insect pests and diseases. C. ohridella can be controlled with chemical insecticides, but these are difficult to apply safely and efficiently to large trees, are expensive, and pose environmental hazards. A much safer and more practical means of control is to remove fallen leaves during the autumn and winter. These can then be either composted thoroughly or burnt, to destroy the over-wintering pupae, or, where collected into smaller heaps, as in gardens, covered with a layer of soil or other plant material to prevent adult emergence. In the long-term, it is expected that permanent and sustainable control of C. ohridella will be achieved through the introduction and release of natural enemies from the moth's area of origin.
Keywords:
Aesculus hippocastanum o defoliation o horse chestnut o Cameraria ohridella o plant health
THE LAURISSYLVA OF MADEIRA: CONTEMPORARY STATUS OF A TERTIARY FOREST
John R. Packham*
Summary
A considerable portion of the Laurel Forest (Laurissylva) of the island of Madeira, first colonized in 1420, survives virtually intact though its integrity is threatened by the introduction of acacias, eucalypts, Douglas fir and other forest trees. The present state of knowledge regarding the origin, history and dynamics of this remarkable forest is outlined. As in many countries with a Mediterranean climate, the number of introduced species is very great and there is a danger that some endemic species may be lost. There is a strong case for international support for the continued conservation and protection of this forest.
Keywords:
endemic species o globalization o Laurel Forests o Macaronesia o Tertiary survival
SOIL INJECTIONS OF CARBOHYDRATES IMPROVE FINE ROOT GROWTH OF ESTABLISHED URBAN TREES
Glynn C. Percival*, Gillian A. Fraser** and Sally Barnes***
Summary
Four established mature tree species (Aesculus hippocastanum L., Betula pendula Roth., Prunus avium L. and Quercus robur L.) com-monly planted in UK urban landscapes were subjected to soil injections of the carbohydrate sucrose at 25, 50 and 70g per litre of water. Fine root dry weight was recorded at month 5 following soil injections. Soil injections of sucrose significantly increased fine root dry weight compared to controls, however; growth responses were influenced by species and the con-centration of sucrose applied. Results indicate soil injections of sucrose ³ 50g litre of water may be able to improve root growth of established mature trees. Such a response is desirable as root damage following con-struction is a frequent problem encountered by established trees growing in UK towns and cities.
COSTS OF URBAN WOODLAND MANAGEMENT
Rodney Helliwell*
Summary
The costs of managing urban woodlands are briefly discussed, together with responses to a questionnaire. Some comments taken from replies to the questionnaire are quoted, and a suggested framework for estimating likely costs of silvicultural management is proposed..