©2023 International Society of Arboriculture 94 distributions. Parameters in the none tier were not expected to be limiting, had relatively low correlation values, and had narrow data distributions. Parameters in the low and moderate tiers fell in between those extremes for these 3 weighting criteria. For the third research question, analysis of vari- ance (ANOVA) with Tukey-Kramer Honestly Signif- icant Difference (HSD) testing was used to examine the responses of labile organic parameters (SOM, POM, POXC, PMC, SOLV, MBC, and MBN) as a result of the soil amendment (biosolids) application. Labile organic matter measurements were deter- mined on soils from the spring and fall collections. Percent changes in each of the parameters were com- puted for each plot. The ANOVA analyses were con- ducted on data from the fall sampling and the percent change data for each parameter. The labile organic matter parameter that most significantly responded to treatments was included in the RUSI model as a 16th parameter for the organic weighted RUSI model (RUSIow). The RUSIow model with the labile organic matter parameter was then tested for correla- tion with urban tree condition metrics using the previ- ously described methods. RESULTS AND DISCUSSION RUSI Significantly Correlates with Urban Tree Health in Wisconsin Across all 3 Wisconsin cities, RUSI scores significantly (P ≤ 0.05) correlated with tree condition (R = 0.32), tree condition index (R = 0.29), and urban tree health (R = 0.29)(Figure 1). The RUSI scores were not sig- nificantly correlated with leaf greenness (SPAD), diameter, height, or crown volume. These results con- firm findings of the original RUSI study (Scharen- broch et al. 2017) and again suggest that the model is a better predictor of tree health, not growth. Correlation strength between RUSI scores and urban tree health metrics tended to be weaker than in the previous study (Scharenbroch et al. 2017). The observed tree performance and site quality ranges were narrower in this study (RUSI scores = 51.0 to 81.1) compared to the initial study (RUSI scores = 30.0 to 82.2). This reduced variability truncates the data dis- tribution and may have led to a reduction in the strength of correlation. The limited geographic extent of the current study resulted in a decreased range of climate factors. Initial study sites occurred in 4 states with mean annual temperatures ranging from 6.7 to first sampling period. The weighted RUSI models were compared to the nonweighted RUSI model, which had an equal weight distribution for the 15 parameters. Parameter weights for the weighted RUSI (RUSIw) were assigned based on limiting factor rank, relative correlation strengths to tree metrics, and data distri- butions. The 15 parameters were ranked 1 to 15 based on their potential limitation for tree health and growth (Table 4). Parameters that were expected to be more limiting received a lower rank. The R-correlation val- ues for the 15 RUSI parameters and each tree metric were determined (Table 5). Data distributions were examined to determine the mean, standard deviation, minimum, and maximum scores for each of the RUSI parameters (Table 2). Four weighting tiers (and weights) were established: none (0.00), low (0.04), moderate (0.09), and high (0.13). Parameters in the high tier were expected to be limiting, had relatively high cor- relation to tree metrics, and had relatively wide data Scharenbroch et al: Towards an Improved Rapid Urban Site Index Table 4. Potential limitation to tree health and growth for each of the RUSI parameters. The lower the rank, the more limiting that parameter was expected to be for tree growth and health based on expert opinions and professional experiences of the primary investigators. Precipitation (PPT), growing degree days (GDD), exposure (EXP), traffic (TRA), infrastructure (INF), surface (SUR), estimated rooting area (ERA), penetration (PEN), A-horizon (HOR), texture (TEX), structure (STR), wet aggregate stability (WAS), soil organic matter (SOM), electrical conductivity (EC), and pH. Property Rank PPT 15 GDD 14 EXP 12 TRA 13 INF 10 SUR 11 ERA 4 PEN 3 HOR 5 TEX 1 STR 2 WAS 6 SOM 7 EC 8 pH 9
March 2023
| 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
