Arboriculture & Urban Forestry 38(5): September 2012 NH4 h-1 g-1 from microbial biomass N values, assuming 8/1 microbial C/N (Inubushi et al. 1991), and used to calculate two microbial ef- ficiency indices. The metabolic quotient (qCO2 +/NO3 / mg MBC g-1 and the ratio of MBC to soil C (MBC/TOC). ) mg CO2 Statistical Analyses Tree Performance Tree age (years) was determined by collecting increment cores (one per tree at 1 m from ground) with a tree increment borer. Increment cores were mounted on grooved wood blocks, sanded using progressively finer sandpaper to help distinguish rings, and analyzed using a Velmex stage micrometer and a Metron- ics Quick-Chek 1000 (Heidenhain, Schaumburg, Illinois, U.S.). The program Measure J2X v4.2 (VoorTech Consult- ing, Holderness, New Hampshire, U.S.) was used to record an- nual ring-widths to the nearest 0.001 mm. The mean diameter growth rate (mm yr-1 ) was computed as the mean annual incre- ). Tree trunk diameter (cm) was measured at 1.38 m with a Lufkin diameter tape (Lufkin, Lufkin, Texas, U.S.). The short and long diameters of the crown were measured from the trunk to dripline, with crown area (CA) (m2 ) = crown width long * crown width short * π / 400 (Uzoh and Ritchie 1996). Leaf chlorophyll content (leaf greenness) was measured on ten random leaves per tree using a SPAD-502 Plus Chlorophyll meter (Konica Minolta, Tokyo, Japan). After measurement the ten leaves were collected and composited per tree, stored on ice, ground with a mortar and pestle in the laboratory, and ana- lyzed for total N (%) by automated dry combustion (Elementar ment growth throughout the tree’s lifespan. Tree height (m) was measured using a Suunto clinometer (Suunto, Ogden, Utah, U.S.). Tree height growth rate was tree height divided by tree age (m yr-1 Statistical analyses were conducted using SAS JMP 7.0 soft- ware (SAS Institute Inc., Cary, North Carolina, U.S.). Data distributions were checked for normality using the Shapiro- Wilk W test. All soil responses aside from clay, WAS, ρb water content, NH4 , dissolved organic N, Mg, and microbial bio- , + mass N, required data transformations or non-parametric tests. Variables were grouped into physical, chemical, and biological categories. Multivariate statistical analysis was conducted in two steps as suggested by Hatcher and Stepanski (1996). Mul- tivariate analysis of variance (MANOVA) was used to detect significant location effects on at least one physical, chemical, or biological variable assessed. After meeting the criteria, analy- sis of variance (ANOVA) of individual parameters was run on all parameters. The obtained F statistic was used to test the null hypothesis of no location effect. Those variables for which the F statistic was significant (P ≤ 0.05) and variance was low (CV ≤ 60) (Hatcher and Stepanski 1996), were retained for further analyses. Treatment mean separations were interpreted using Tukey-Kramer’s HSD test to protect for the overall error rate. Other studies have found principal component analyses (PCA) to be practical and effective tools in selection of appropriate soil quality indicators for predicting plant performance (Maddonni et al. 1999; Brejda et al. 2000a; Brejda et al. 2000b; Shukla et al. 2006; Rodrigues de Lima et al. 2008; Bautista-Cruz et al. 2011). Retained parameters from the ANOVA were used in PCA for fur- Table 1. Trunk, crown, root, structure, growth, pest, and life expectancy factors comprising the urban tree condition index. Tree condition index is the summation of the seven scores. Adapted from Webster (1979). Factor 5 Trunk Crown Root Sound and solid throughout Dense, evenly balanced crown Three or more visible and evenly balanced root flares (<2 cm deep) Structure No major limbs missing, broken, or dead; no narrow crotches; good radial distribution Growth Pest >15 cm annual twig elongation No insect or disease problems Life expectancy ©2012 International Society of Arboriculture >50 years 4 Minor damage Dense, slightly unbalanced crown Three or more visible and slightly unbalanced root flares (<2 cm deep) Narrow crotch on a major limb 10 to 15 cm annual twig elongation Minor insect or disease problems 30 to 50 years Score 3 Early decay signs Thin or severely imbalanced crown Less than three visible or severely unbalanced root flares (<2 cm deep) One of major limbs is dead or broken 5 to 10 cm annual twig elongation Minor insect and disease problems 20 to 30 years 2 Extensive decay, hollowness, cambium damage Thin and slightly imbalanced crown No visible root flares and structural roots (2 to 15 cm deep) Two or three major limbs Two or three major limbs with narrow crotches and one broken or dead major limb with narrow crotches and broken or dead major limbs 2 to 5 cm annual twig elongation Serious disease or insect problems (e.g., canker, wilt, bark beetles, wood borers) 10 to 20 years <2 cm annual twig elongation Serious disease and insect problems (e.g., canker, wilt, bark beetles, wood borers) <10 years 1 Same as two, but cross-section is a half circle Thin and severe imbalanced crown Structural roots (>15 cm deep) evolved - kg-1 d-1 ). Microbial biomass C (MBC) was calculated 217 Vario EL III CHNOS, Elementar, Hanau, Germany). A qualita- tive tree condition index (TCI) value was calculated based on Webster (1979). The TCI was a summation of trunk, crown, root, structure, growth, pest, and life expectancy factors (Table 1).
September 2012
| Title Name |
Pages |
Delete |
Url |
| Empty |
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. You will be contacted by Washington Gas with follow-up information regarding your request.
This process might take longer please wait
