Arboriculture & Urban Forestry 39(4): July 2013 Arboriculture & Urban Forestry 2013. 39(4): 173–181 173 Impact of Tree Size and Container Volume at Planting, Mulch, and Irrigation on Acer rubrum L. Growth and Anchorage Edward F. Gilman, Jason Miesbauer, Chris Harchick, and Richard C. Beeson Abstract. Some trees uproot in storms apparently due to root deflections that occur during nursery production. Root deflection in a nursery container may lead to poor anchorage because of insufficient root growth into the landscape soil, and container volume/tree size at planting may influence root deflection. This study was designed to evaluate establishment, root growth, and anchorage six years after planting Acer rubrum L. trees of four different sizes from four corresponding container volumes and maintaining them with two irrigation regimes. Impact of mulch on establishment and root growth was also evaluated. Trees from the largest containers grew slowest in the first three years due primarily to water stress. Trunk tilt during winching tests increased due to greater root deflection, less mass of the root-soil plate, and reduced root growth into the landscape soil with increasing container volume and tree size. In contrast to the poorly anchored larger trees that had most of their large roots retained in the original planted root ball volume, the largest roots on trees from smaller containers grew freely into land- scape soil. This resulted in stable trees with many stiff, straight roots pushing down against mineral landscape soil outside the root ball during winching. Trees planted from smaller containers appear to anchor sooner than trees from larger containers and would be more stable in a storm. Key Words. Bending Stress; Container Production; Root-soil Plate; Straight Roots. Roots that naturally arise on trees originating from seeds (seed- ed-in-place) develop in concert with soil conditions; whereas, roots of planted trees are forced to acclimate to the new envi- ronment. Cultural practices in nurseries influence the position and shape of the largest roots (Ortega et al. 2006; Hewitt and Watson 2009) and the orientation of the root tips (Salonius et al. 2000), which dictate early root growth of trees in their new location. Nursery-induced changes in root morphology have been associated with delayed establishment and poor anchorage compared to trees seeded-in-place (Lindström and Rune 1999). Coutts (1983), Stokes (1999), and others have studied tree an- chorage and stability in plantation-grown forest stands. Models for some species can explain a sizable portion of variation in tree stability from mass of the root-soil plate (RP), rooting depth, mor- phology, and soil type (Fourcaud et al. 2008). Though advances have been made in describing the mechanics of tree anchorage on trees seeded-in-place or planted from small root balls typical of plantations, few studies have been performed on trees planted from the much larger root balls typical in urban landscapes. Modeling root growth rates in USDA Hardiness Zone 5 (Il- linois, U.S.), Watson (1985) suggested that small nursery stock [10 cm trunk diameter (caliper)] would establish and grow quicker than larger trees. Gilman et al. (1998) confirmed that small caliper live oak (Quercus virginiana Mill.) trees (6.3 cm) planted into the landscape in zone 8 (Florida, U.S.) from nursery containers grew at a faster rate than larger trees, but not when transplanted from a field nursery. Furthermore, the smaller field-grown trees were the same size as the container- grown trees that started out much larger three years earlier. This is likely due to greater defoliation and water stress for trees planted from larger containers (Gilman et al. 2010a). Struve et al. (2000) suggested that smaller trees in their study did not grow faster to become equivalent in size to the larger trees because the larger trees in that nursery were typically the most vigorous and therefore grew fastest. This keen observa- tion has merit when comparing trees from the same block of trees in the same nursery, but may not hold true when com- paring small trees from one nursery with larger trees from a different block or from a different nursery. These studies sug- gest that tree size and root ball volume at planting impact establishment and growth rate of trees in urban landscapes. However, there is no information on establishment and anchor- age of trees planted from containers larger than about 170 L. Susceptibility to drought stress for trees planted from contain- ers with soilless (typically bark, organic matter, and sand) sub- strate has been attributed to a dense root system inside the con- tainer (Harris and Gilman 1993) that dries quickly (Marshall and Gilman 1998) because of low water-holding capacity (Spomer 1980). The low substrate density of a soilless container root ball also increases susceptibility of overturning in storms com- pared to trees transplanted from a field nursery with a heavier mineral soil root ball (Gilman and Masters 2010). Trees grown in a soil-based substrate in containers have not been studied. Mulch and irrigation management can drastically impact soil properties (Scharenbroch 2009) and tree establishment rate (Gil- man and Grabosky 2004), and could influence anchorage by im- pacting root growth. Mulch application to the surface of a planted root ball and to the surrounding soil of relatively young trees has been associated with reduced tree survival (Arnold 2005; Singer and Martin 2009), slightly enhanced growth rate (Arnold and ©2013 International Society of Arboriculture
July 2013
| 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
