278 Burcham et al.: Internal Defects and Their Effect on Trunk SurfaceTemperature associated with decayed wood inside the stem (Schwarze et al. 1997; Costello and Quarles 1999; Larsson et al. 2004; Rabe et al. 2004; Nicolotti et al. 2009; Johnstone et al. 2010). Wood decay infections cause measurable changes to the physical, mechanical, chemical, and biological wood properties evalu- ated by the devices, including low density and altered moisture relations (Cartwright and Findlay 1958). However, the devices vary considerably in terms of their accuracy, speed of measure- ment, and invasiveness (Ouis 2003; Kersten and Schwarze 2005). The use of infrared (IR) cameras as tree diagnostic devices has been proposed as a non-destructive and rapid technique for assessing internal defects, including wood decay (Catena 2003). The principles, advantages, and disadvantages of the technique have been extensively reviewed (Catena and Catena 2008). Principally, the technique attempts to associate chang- es in the thermal properties of wood containing defects with surface temperature anomalies (Catena et al. 1990). In this method, the trunk surface temperature of trees is captured using IR cameras. The relatively low density, structural discontinu- ity, and altered moisture content of internal defects modify the wood’s thermal properties, including thermal conductivity, ca- pacity, and diffusivity (Scheffer 1936). These material property changes may, under certain environmental conditions, render trunk surface temperature anomalies observable in the IR im- age. The earliest publications reported that trunk surface tem- peratures were highly variable and relatively cooler at locations overlying internal defects (Catena et al. 1990). Although initial attempts to verify the technique relied heavily on qualitative case studies, recent research efforts have evaluated the tech- nique using quantitative measurement and analysis approach- es (Bellett-Travers and Morris 2010; Burcham et al. 2011). In particular, Burcham et al. (2012) found that relatively large internal defects, occupying at least 76% of the stem cross-sectional area (CSA), were required to produce a mea- surable reduction in surface temperature under controlled conditions. Similarly, Bellett-Travers and Morris (2010) re- ported that surface temperature was most correlated (r2 = 0.31 - 0.55) with the radial wood thickness exclusively in trees containing a distinct, compartmentalized internal cav- ity. The relationship between these features was not pres- ent in healthy specimens or those containing incipient de- cay (Bellett-Travers and Morris 2010). Collectively, these results suggest that the IR camera technique may effectively identify a narrow range of relatively large internal defects. The potential diagnostic advantages offered by the IR camera technique could be significant in urban areas. First, there is some evidence showing that wounds created by inva- sive diagnostic tools serve as infection courts for wood decay fungi (Kersten and Schwarze 2005), and the non-invasive in- frared camera measurements could provide an alternative. Second, the IR camera offers comparatively quick measure- ment speeds. Third, the broad spatial orientation of the IR image could provide information about larger areas of the trunk. However, research clarifying the resolution and accu- racy of this technique is needed. This study was designed to: 1) evaluate the relationship between the internal defects and surface temperature measurements collected with an IR cam- era, and 2) evaluate methods of interpreting the IR images using qualitative and quantitative data analysis techniques. MATERIALS AND METHODS Selection of Plant Material Forty-eight Casuarina equisetifolia were selected from a sandy coastal forest situated at the eastern edge of Singapore (lat. 1°20’51.33”N, long. 103°59’53.45”E) for inclusion in this study. The study area was populated, principally, by this actinorhizal pioneer species, occasionally supplanted by the coastal species Terminalia catappa L. (Combretaceae) and the non-native pioneer Acacia auriculiformis A. Cunn. ex Benth. (Leguminosae). The trees were growing on reclaimed land originally formed in 1991 by the deposition of marine sand, dredged from the seabed and containing less than 10% fines, on top of a highly compressible layer of Singapore marine clay (Bo et al. 2005). Trees were selected for study based on the satisfaction of at least one pre-defined criterion, including 1) external decay associated signs and symptoms, or 2) a stem diameter, exceeding 40 cm, measured at 1 m above the ground. After selection, the trees were assigned a unique alphabetic label and marked with high-visibility plas- tic tape. This tape increased visibility of the selected trees in the forest and served as a tag for subsequent experimental work. Height (m), diameter (cm), and geospatial position (lat- itude and longitude) were measured and recorded (Figure 1). Figure 1. The 48 sampled Casuarina equisetifolia were measured with an infrared camera and removed for study from an early successionary coastal forest situated at the eastern edge of Singapore (1°20’51.33”N 103°59’53.45”E). ©2012 International Society of Arboriculture
November 2012
| Title Name |
Pages |
Delete |
Url |
| Empty |
Ai generated response may be inaccurate.
Search Text Block
Page #page_num
#doc_title
Hi $receivername|$receiveremail,
$sendername|$senderemail wrote these comments for you:
$message
$sendername|$senderemail would like for you to view the following digital edition.
Please click on the page below to be directed to the digital edition:
$thumbnail$pagenum
$link$pagenum
Your form submission was a success.
Downloading PDF
Generating your PDF, please wait...
This process might take longer please wait
