Frequency and Severity of Trunk Decay in Street Tree Maples in Four New York Cities (original) (raw)
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Decay, defects and condition of street trees in four Upstate New York cities
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Throughout most of New York State, maple species are the most common street tree. It is not unusual for Norway (Acer platanoides), silver (A. saccharinum), sugar (A. saccharum), red (A. rubrum), and other maples species to comprise over 50% of the street tree population in communities of all sizes. As in many areas of the country, maples on the streets today were planted to replace the American elms (Ulmus americana) that were lost as a result of the Dutch Elm Disease epidemic that started in the 1930s. Many cities in New York are therefore faced with an aging population of maples that make up a substantial portion of their street tree populations. The cities we selected for this study of decay and tree health were Albany, Buffalo, Rochester, and Syracuse. These cities are the largest in upstate New York and together have over 67,000 trees that are greater than 12 inches in diameter. They are also typical of other communities in the state in that Norway maple is over 36% of the larg...
The measurement of wood decay in landscape trees
The evaluation of wood in a tree trunk is essential for tree risk assessment, however the accurate measurement of decay is still in its infancy. A review of the current methods used for the field measurement of wood decay in landscape trees is presented. The methods are compared in terms of the damage caused to tree tissues, ease of use and the level of accuracy. Moderately invasive decay detecting devices, such as constant feed drills, are accurate for locating wood decay in a tree. In contrast computerized tomography devices are less damaging to tree tissues, but results may be difficult to interpret.
COMPARATIVE DECAY OF HEARTWOOD AND SAPWOOD 0 1 ; RED MAPLE
Heartwood and sapwood of red maple showed little decay resistance when exposed to the brown. rot fungus, Oligoporus placentus, the white-rot fungus, Trametes versicolor, and the soft-rot fungus 17haetomiurn globosum. Heartwood did, however, show a slight resistance (lower weight losses) rel. xtive to sapwood. Action of the white-rot fungus was enhanced by high moisture content, while tha~ of the brown-rot fungus was enhanced by lower moisture content. Test blocks exposed to the whiterot fungus decayed to higher weight losses when supported by sapwood feeder strips than when supported by plastic mesh. For test blocks exposed to the brown-rot fungus, blocks supported on plastic mesh decayed to higher weight losses than those on feeder strips, most likely because of the lower moisture content of the blocks on plastic mesh. For test blocks exposed to the soft-rot fungus [here were slightly higher weight losses using the feeder strip method.
The predictability of tree decay based on visual assessments
Journal of …, 1996
A field study was conducted to measure the predictability of tree decay based on visual assessments. Predictions made by individual arborists, tree surgeons, and forest ecologists were compared with the actual amounts and distributions of decay in 10 hazardous laurel oaks (Quercus hemisphaerica) that were dissected. The mean deviations of predicted area of decay and predicted loss in strength from actual values were 0.4% and 2%, respectively. The interquartile range for predicted decay area was +12 to -15%; for strength loss it was +8 to -8%. Accuracy of the predictions improved with feedback. The results of this study suggest visual assessment can be a reliable means of predicting the internal extent of decay and hollow in potentially hazardous urban trees.
Wood decay in living and dead trees: A pictorial overview
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Pioneering research by Alex L. Shigo and his associates has produced a series of pictorial guidelines to provide a better understanding of how trees respond to wounding and subsequent microbial infections that lead to wood decay. The purpose of this paper is to visually summarize through the use of 96 color photographs and illustrations, the varied patterns of wood discoloration and decay observed in the dissection of thousands of trees. This information has served as a conceptual framework for understanding the biochemical processes that limit the spread of wood-destroying infections initiated by wounding during the maturation of all trees. This understanding has helped those who work with forests, trees, and wood to resolve practical problems and improve the health and productivity of trees and forests.
Forestry: An International Journal of Forest Research
The occurrence (probability) and extent (proportion) of tree internal stem decay are important attributes influencing potential wood quality and value, but variation in decay by species, tree size and geographic range are rarely evaluated and modelled. In this analysis, we used 1246 destructively sampled trees across 33 species in the northeastern United States and New Brunswick, Canada to determine the factors influencing the combined probability and proportion of decay. In the process, we evaluated three modelling approaches including a two-part conditional model, multinomial model and generalized additive model for location, scale and shape (gamlss) that simultaneously predicted both probability and proportion of decay. Predictive capability for all three methods were nearly identical when classifying decay occurrence. Compared with the other methods, the gamlss model had a lower mean bias and root mean square error (RMSE) when predicting decay extent. Tree diameter to height ratio (ratio of diameter at breast height to total height), height, crown ratio, species tolerance to flooding and drought, leaf longevity, and an assessment of perceived tree risk of mortality (risk class) were selected as predictors in the best overall model for decay occurrence. For predicting decay extent, the best model included risk class, crown ratio and the last freezing date of spring. Further analysis identified significant species differences, which we used to develop functional species groupings based on decay occurrence and extent. Despite these observed relationships, a high degree of unexplained variation remained, highlighting the challenges of modelling decay in trees of different species across a range of growing environments.
Decay patterns in silver maple (Acer saccharinum) trees converted from roundovers to V-trims
ARBORICULTURE …, 2006
Trees growing beneath electrical power lines are often subjected to heading cuts made during roundover trimming. Heading cuts create wounds that allow decay to enter the branch, and a decay column will form if the tree does not contain it with compartmental reaction zones. The presence of a sizable decay column may predispose the leader to failure, especially when the tree has been converted from a roundover to a V-trim. The objectives of this study were to quantify the amount of decay in silver maples (Acer saccharinum L.) converted from roundover to V-trims and to develop models to allow utility arborists to estimate the extent of internal decay columns. Parent stems (leaders) were removed from converted trees, cut into 50 cm (20 in) sections, and measured for internal and external decay. Eighty percent of the leaders had internal decay columns beginning within 50 cm (20 in) of the heading cut and internal decay columns were found to be over 2 1 ⁄2 times longer than the length of external decay. Models are presented to predict the length and volume of internal decay from external measurements on the leader, including length of external decay.
Low street tree survival rates and the resulting short lifespans are frequently discussed but inadequately quantified in urban forestry literature. This study addresses street tree survival rates with a meta-analysis of previous literature and a case study assessment of street trees in Philadelphia, USA 2-10 years after planting. Reported survivorship rates from 16 previous studies were compiled. Estimated annual survival rates for individual past studies were mostly above 91.0%. To estimate the annual street tree survival rate across multiple studies, a subset of previous studies was pooled for regression analysis of ln transformed cumulative survivorship vs. time since planting. Lifespan metrics were estimated using the annual survival rates determined from regression analysis. Based on the meta-analysis, we estimated that street tree annual survival rates ranged from 94.9 to 96.5%, and street tree population half-life ranged from 13 to 20 years. Estimated mean life expectancy ranged from 19 to 28 years, which is considerably longer than the 7-or 13-year street tree average lifespan reported in previous studies. Estimated annual survival rates and lifespan metrics were similar in the Philadelphia case study. Urban forest researchers are encouraged to use demographic concepts and analyses in the study of tree survival and mortality, and to monitor tree survival at repeated time intervals every few years.