Search

Reinhardt et al. (E. Reinhardt, J. Scott, K. Gray, and R. Keane, Can. J. For. Res. 36: 2803-2814, 2006) questioned the validity of the regression equations for estimating canopy base heights in coniferous forest fuel types developed by Cruz et al. (M.G. Cruz, M.E. Alexander, and R.H. Wakimoto, Int. J. Wildland Fire, 12: 39-50, 2003) to produce logical results when applied to simulations involving low thinning. This turns out to be an error in interpretation with regard to the stand height input parameter. Reinhardt et al. (E. Reinhardt, J. Scott, K. Gray et R. Keane, Rev. can. rech. for. 36 : 2803-2814, 2006) ont mis en doute la validité des équations de régression servant à estimer la hauteur de la base du couvert dans les types de combustibles associés aux forêts de conifères, développées par Cruz et al. (M.G. Cruz, M.E. Alexander et R.H. Wakimoto, Int. J. Wildland Fire, 12 : 39-50, 2003), quant à leur capacité à fournir des résultats logiques lorsqu'elles sont utilisées dans des simulations impliquant une éclaircie par le bas. Il s'agit en fait d'une erreur d'interprétation concernant le paramètre d'entrée pour la hauteur du peuplement. [ABSTRACT FROM AUTHOR]

Purpose To evaluate the diagnostic performance of meibometry in classifying and quantifying Meibomian gland dysfunction(MGD) Methods Ninety‐six patients with MGD (138 eyes, 62 women, 34 men) and 30 normal control subjects(55 eyes)were enrolled. Eighty six eyes were classified as high delivery (HD)‐MGD (meibomian seborrhea/hypersecretory MGD), 52 as low delivery (LD)‐MGD on the basis of expression quality scores and morphological signs. Direct Meibometry (DM) measurements were made with an MB550 Meibometer (Courage‐Khazaka GmbH). Standard curves were constructed relating arbitrary Meibometer optical density units (AU). Integrated Meibometry (IM) was performed on scanned images of the lipid blots. Symptoms were scored by OSDI,Schirmer test I, Break Up Time (BUT), tear osmolarity (Tearlab, Ocusense), conjunctival scraping cytology were performed. Statistical analysis used SPSS 14.0 and MedCalc 5.0 Results AU values plotted on a log scale correlated highly with the lipid equivalent values (R2= 0.913). Significant differences were found between control subjects vs all MGD patients and between HD vs LD‐MGD patients for all the parameters evaluated. In particular: controls: 300+/‐121 AU (0.04+/‐0.015 microliter), LD‐MGD: 218+/‐122 AU (0.03+/‐0.015) and HD‐MGD: 564+/‐115 AU (0.07+0.015) (median+/‐SD). Significant correlation was found DM vs IM (r=0.691,p<0.0001) and DM was shown to be correlated with BUT, OSDI score, scraping score and tear osmolarity, especially in LD‐MGD patients. The selected DM diagnostic cut off for LD‐MGD was <275 AU (sens 73, spec 60, PPV 63) and for HD‐MGD was >450 AU; (sens 86, spec 87, PPV 91) Conclusion Meibometry is confirmed to be a reliable method to distinguish normal subjects from MGD subgroups with a good degree of accuracy [ABSTRACT FROM AUTHOR]

Leaf area index (LAI) – defined as one half of the total green leaf area per unit ground surface area – can be determined by direct or indirect methods. Three major sources of errors exist in indirect LAI measurements: within-shoot clumping, beyond-shoot clumping and non-photosynthetic components. The effect of non-photosynthetic components on LAI measurements can be described by the woody-to-total area ratio, ; however, no convenient and efficient indirect methods have been developed to estimate , especially the variations in with zenith angle , (). We describe the development and use of a multispectral canopy imager (MCI) to estimate and () by considering the effects of non-random distributions of canopy elements and woody components and the overestimation of needle-to-shoot area ratio on woody components. The MCI, which mainly comprises a near-infrared band camera (Fujifilm IS-1), two visible band cameras (Canon 40D), filters and a pan tilt, was developed to measure clumping index, woody-to-total area ratio and geometric parameters of isolated trees. Two typical sampling plots (Plots 1 and 5) chosen from among 16 permanent forest experiment plots were selected for the estimation of and (). The non-random distributions of canopy elements and woody components were estimated separately at eight zenith angles (from 0° to 70° in increments of 10°) using MCI images based on the gap size distribution theory. The visible/near-infrared image pairs captured by the MCI were able to discriminate among sky, leaves, cloud and woody components. Based on three methods of estimation, we obtained woody-to-total area ratios of 0.24, 0.19, 0.19 for Plot 1 and 0.23, 0.18, 0.17 for Plot 5. If clumping effects were ignored, values were overestimated by as much as 21% and 24% at Plots 1 and 5, respectively. We demonstrated that () varied with the zenith angle, with variations in the range of 3–33% at Plot 1 and 2–65% at Plot 5. A new formula for the precise determination of LAI is proposed. [ABSTRACT FROM AUTHOR]

An overview of the article "Applying Spatial Analysis Techniques to Assess Tennessee Urban Forests," to be published in the November 2008 issue of the "Southern Journal of Applied Forestry" is presented. It describes how spatial analysis techniques were used to evaluate urban forest canopy cover in 133 municipal urban areas across Tennessee. After comparing municipalities based on their participation in the Tree City USA program, results indicate that cities participating in this forestry initiative exhibit higher levels of urban forest canopy cover.