The relationships of structural root depth, stem girdling roots, stem diameter, and boulevard width were studied on the condition of four tree species (Acer saccharum L., Celtis occidentalis L., Fraxinus pennsylvanica Marsh, and Tilia cordata Mill.) grown as street trees. The relationship between depth from the soil surface to the structural roots and development of stem encircling roots and stem girdling roots was also determined. Stem girdling roots, boulevard width, and root depth were significant predictors of tree condition. Tree condition was greater as boulevard width increased, but stem girdling roots and structural root depth had a negative relationship on tree condition. Depth to structural roots was positively related to the percentage of the tree stem circumference with stem encircling roots and also for stem girdling roots. For every cm the structural roots were below the soil surface, 3.3 % of the stem was encircled. Thus, a 10 cm root depth translates to approximately 1/3 of the stem with encircling roots. With stem girdling roots, an approximate 1 % of the stem was girdled for each cm that structural roots were below the surface. Results from the measurement of 398 trees that were approximately 10–20 years post planting provide additional justification for maintaining structural roots at the soil surface. Results also demonstrate the importance for planning tree planting locations with adequate boulevard widths to foster tree health. Findings have implications with nursery production, tree planting, and arboricultural treatments to remove soil away from tree stems and expose structural roots at planting and subsequently with established trees.

研究了四种树种（条件宽度结构根系深度的关系，茎环剥根，茎直径，和Boulevard糖槭L.，朴树望江南L.，美国红梣Marsh和小叶椴磨坊。）生长为街头树木。还确定了从土壤表面到结构根的深度与茎围根和茎环根的发育之间的关系。茎环根，林荫道宽度和根深是树木状况的重要预测指标。随着林荫道宽度的增加，树木状况变得更大，但茎环的根部和结构根深与树木状况呈负相关。到结构根的深度与围绕茎的树茎周长百分比以及与茎环缠结的根成正比。每厘米的结构根都在土壤表面以下，茎的3.3％被环绕。因此，根部深度为10 cm时，约有根部环绕的茎大约转化为茎的1/3。有根茎环 对于结构根在表面以下的每厘米，约有1％的茎被束紧。种植后大约10–20年的398棵树木的测量结果为保持土壤表面的结构根提供了进一步的依据。结果还证明了规划具有足够林荫大道宽度的树木种植位置以促进树木健康的重要性。这些发现对苗圃生产，植树和树木栽培（从树茎上除去土壤并在种植时露出结构根）和随后的成熟树木进行树木栽培处理具有重要意义。种植后大约10–20年的398棵树木的测量结果为保持土壤表面的结构根提供了进一步的依据。结果还证明了规划具有足够林荫大道宽度的树木种植位置以促进树木健康的重要性。这些发现对苗圃生产，植树和树木栽培（从树茎上除去土壤并在种植时露出结构根）和随后的成熟树木进行树木栽培处理具有重要意义。种植后大约10–20年的398棵树木的测量结果为保持土壤表面的结构根提供了进一步的依据。结果还证明了规划具有足够林荫大道宽度的树木种植位置以促进树木健康的重要性。这些发现对苗圃生产，植树和树木栽培（从树茎上除去土壤并在种植时露出结构根）和随后的成熟树木进行树木栽培处理具有重要意义。