ii based on FT-IR spectra collected prior to pathogen infection using the three chemometric approaches: soft independent modeling of class anal- ogy, partial least squares regression, and SVM. While further validation of the predictive models is needed, the results suggest that the approach may be useful as a tool for screening and breeding Austrian pine for resistance to D. sapinea. Furthermore, this approach may have wide appli- cability in other tree/plant pathosystems of concern and economic value to the nursery and ornamental industries. Keywords. Diplodia sapinea; Diplodia Tip Blight; FT-IR; Pinus nigra; Predictive Modeling. Jian Lin, Charles N. Kroll, and David J. Nowak Ecosystem Service-Based Sensitivity Analyses of i-Tree Eco ...............................................287 Abstract. Trees are known to provide various ecosystem services and disservices to urban communities, which can be quantified using models based on field and environmental data. It is often uncertain how tree structure and environmental variables impact model output. Here we per- form a sensitivity analysis (SA) of i-Tree Eco, a common urban forest model, to analyze the relative impact of different model inputs on three module outputs: biogenic volatile organic compound (BVOC)(isoprene and monoterpenes) emissions, carbon storage and sequestration, and dry deposition of nitrogen dioxide, sulfur dioxide, and ozone. The SA methods included novel applications of the Morris one-at-a-time method and a variance-based decomposition method, which integrates Monte Carlo simulation with Latin hypercube sampling and Iman Conover anal- ysis. A case study was performed in New York City, New York, USA, with field plot data collected in 2013. Genus has the largest influence on BVOC emissions by determining base emission rates and its high interactions with other input factors, and BVOC emissions are sensitive to leaf biomass in a concave manner and temperature in a convex manner, while isoprene emissions show a strong linear relationship with photo- synthetically active radiation (PAR). Diameter at breast height plays the most important role for both carbon storage and sequestration estima- tors; crown light exposure and tree condition are also important for carbon sequestration. Dry deposition velocity is sensitive to leaf area index and relative humidity in a nearly linear way, while sensitive to temperature and PAR in a concave manner. The results provide guidance to facil- itate future field plot campaigns and model development. The knowledge revealed by the SA is also beneficial for model uncertainty reduction, which in turn facilitates more effective urban forest management and decision-making. Keywords. Air Pollutant; Carbon Storage and Sequestration; Monte Carlo; Urban Forests; Volatile Organic Compounds. Djamel Ouis Monitoring of a Cross-Sectional Vibrational Mode in the Trunk of a Palm Tree ...................307 Abstract. Palm trees, like all other tree species, are living entities that may be subject to the attack of several natural agents which affect the strength of the trunk. The most serious of these damaging agents are parasites and rot fungi, which proliferate in the substance of the stem, destroying its cells and fibers and weakening it. Consequently, this decay affects the physical characteristics of the modes of vibration in the tree trunk regarding resonance frequency, shape, and damping. Advanced stages of rot infection in a tree trunk may reach such an extreme level that substantial amounts of its solid mass are removed, ultimately leading to a hollow trunk rather than one of substance. In cases like these, the trunk presents less resistance to forced vibrations, and the active modes affecting the cross section of the trunk exhibit decreased resonance fre- quency values. This paper aims to present a method based on vibrations which might be employed for tracking a specific mode of radial vibra- tions known as the ovalling mode. To achieve this goal, the trunk of a palm tree was set into vibration via mechanical excitation in the radial direction and its response at some specific point on the trunk was examined. This method uses a single concentrated source of excitation and two vibration sensors, which are diametrically positioned and fastened to the surface of the tree trunk. The ovalling mode might be extracted from the frequency response by adding the signals recorded by the two sensors, which are in phase for a test specimen with a perfectly circu- lar, cylindrical shape made of homogeneous, isotropic material. This study provides a preliminary investigation into the feasibility and reliabil- ity of this nondestructive method when applied for the identification of rot hosting by the trunks of standing trees, wooden poles, and logs, as well as the level of severity of rot attack. Keywords. Inspection; Ovalling Mode; Palm Tree; Resonance; Rot; Trunk; Vibration. ©2020 International Society of Arboriculture
July 2020
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