©2023 International Society of Arboriculture Arboriculture & Urban Forestry 49(2): March 2023 95 The RUSIw model applies the greatest weights to the depth of the A-horizon, soil texture, and soil struc- ture. Surface condition, estimated rooting area, and penetration resistance were assigned the next greatest weights in the RUSIw model. The RUSIw applies no weight to the precipitation and growing degree days scores. The weighting in the RUSIw was developed based on limiting factor rank, relative correlation strengths to tree metrics, and data distributions. An urban tree manager will likely have a reasonable under- standing of the limiting factors for the trees they are managing. They can, and should, utilize that informa- tion to assign greater weights to those parameters that are likely driving site quality differences. Furthermore, some of the RUSI parameters may not be important for separating site quality differences for a particular population of urban trees. This was the case for the current study in which all trees were in a similar cli- mate with similar precipitation and growing degree days. Consequently, the parameter weighting removed those parameters from the RUSI model by assigning a 0.000 weight. 12.9 °C (US Climate Data 2018), mean annual pre- cipitations ranging from 830 to 1,219 mm yr -1 (US Climate Data 2018), and growing degree days rang- ing from 2,808 to 3,948 (Growing Degree Days 2014). Sites in this study occurred in a single state with mean annual temperatures ranging from 6.7 to 8.8 °C (US Climate Data 2018), mean annual precipitations rang- ing from 830 to 876 mm yr -1 (US Climate Data 2018), and growing degree days ranging from 2,378 to 2,696 (Growing Degree Days 2014). The observed decrease in the variability of climate factors related to the limited geographic extent of this study may have reduced the RUSI models’ ability to predict tree performance. Weighting RUSI Parameters Improves Correlation to Urban Tree Health Parameter weighting improved correlation to urban tree condition. The weighted RUSI model (RUSIw) improved the correlation to all urban tree health and growth assessments compared to the nonweighted model (RUSI)(Figure 1). The RUSIw was also sig- nificantly correlated with leaf color, which was not the case for the nonweighted RUSI model. Table 5. Pearson R-correlation values (n = 90) of tree diameter (DIA), tree height (HT), tree crown volume (CV), leaf greenness (SPAD), tree condition (TC), tree condition index (TCI), and urban tree health (UTH) with RUSI scores for 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. RUSI DIA HT CV SPAD TC TCI UTH PPT –0.13 0.14 –0.04 –0.38* 0.05 –0.01 –0.11 GDD 0.06 0.12 0.08 –0.03 0.05 0.02 –0.09 EXP –0.08 –0.27* –0.23* 0.09 –0.01 –0.03 –0.01 TRA –0.01 –0.02 –0.07 0.02 –0.02 0.12 0.04 INF –0.02 –0.15* –0.08 0.09 0.10 0.14 0.19* SUR –0.04 –0.06 –0.05 0.19* 0.14 0.17* 0.15* ERA 0.11 –0.06 –0.01 0.16* 0.11 0.02 0.17* PEN –0.03 0.08 0.09 –0.15* 0.22* 0.23* 0.19* HOR 0.12 0.24* 0.29* 0.04 0.18* 0.24* 0.19* TEX 0.13 0.02 0.16* 0.28* 0.07 0.15* 0.25 STR 0.19* 0.26* 0.31* 0.29* 0.25* 0.21* 0.22* WAS 0.24* 0.19* 0.18* 0.42* 0.08 0.00 –0.02 SOM –0.07 0.10 0.07 –0.04 0.06 0.10 0.14 EC 0.15* 0.09 0.09 0.37* 0.01 –0.09 –0.08 pH 0.02 0.00 –0.05 0.13 0.02 –0.03 0.01 *P ≤ 0.05
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
