Article

Impact of Planting Depth on Fraxinus pennsylvanica 'Patmore' Growth, Stability, and Root System Morphology

Authors:
To read the full-text of this research, you can request a copy directly from the authors.

Abstract

Trees are often deeply planted as a result of nursery and landscape practices. While past research has investigated the impact of deep planting on tree growth and survival, its impact on whole-tree stability is not well documented. Green ash (Fraxinus pennsylvanica 'Patmore') trees were planted at three different depths in research plots and established for nine years. In assessing aboveground growth, planting depth had no effect on stem diameter growth (measured as dbh) (P-value = 0.421; n=32), or tree height (P-value = 0.501; n=32). Static pull tests were conducted to evaluate the consequences of deep planting on tree stability. Using structure from motion (SfM) photogrammetry-derived computer models to assess root architecture, we found the most significant factors affecting tree stability were: 1.) root volumes in the top 10 cm of the soil in a 90-degree wedge on the side opposite of the pull direction, 2.) Root volumes 40.1-50 cm deep in a 90-degree wedge on the side opposite of the pull direction, and 3.) Root volumes deeper than 60.1 cm deep in a 90-degree wedge on the side opposite of the pull direction (final model: P-33 value < 0.001; n=30; adjusted R 2 = 0.852). The importance of structural root morphology throughout the soil profile and implications for urban root-soil relations on tree stability are discussed.

No full-text available

Request Full-text Paper PDF

To read the full-text of this research,
you can request a copy directly from the authors.

... When planting trees, there are many considerations beyond the debate with removing packing materials. Planting depth is perhaps of greater concern (Miesbauer et al. 2019). Tree planting with the RSTZ below the soil surface may result in tree roots growing toward the soil surface and resuming lateral growth at a direction away from or towards the tree stem. ...
Article
Full-text available
When balled-and-burlapped trees are planted, a decision must be made regarding whether the wire basket, burlap, and other packing materials should be removed (completely or partially) or retained. While past research has failed to show a significant impact of either approach with regard to initial growth and establishment, many professionals still question whether a decision to leave the wire basket intact at planting will have longer-term impacts to tree health and stability. In this study, we revisit two nursery trials first initiated in 2011 and 2012 to assess the impact of burlap folding, and full wire basket removal, partial removal, or retention on tree growth and root anchorage five to six growing years after planting. We found that neither stem caliper (min P = 0.249) nor twig elongation (min P = 0.297) differed among removal treatments with the Norway maple (Acer platanoides L.) and ‘Skycole' honeylocust (Gleditsia triacanthos L. var. inermis) trees used in this study. Similarly, we were unable to detect any differences in rooting strength among the removal treatments tested (min P = 0.154). These results serve as further evidence that wire baskets are not a cause of early tree mortality or instability. Index words: Arboriculture, biomechanics, growth and longevity, nursery production, static-pull test, transplanting, transplant shock. Species used in this study: Norway maple (Acer platanoides L.); ‘Skycole' honeylocust (Gleditsia triacanthos L. var. inermis).
Chapter
Deeply planted trees are commonly observed in the urban landscape. However, the effect of deep planting on tree stability is not well documented. Green ash (Fraxinus pennsylvanica 'Patmore') trees were planted at three different depths in research plots and established for nine years. We then conducted static pull tests to evaluate the consequences of deep planting on tree stability. We also evaluated the application of 3-D models derived from structure from motion (SfM) photogrammetry in quantifying root volume and architecture and how those characteristics affected tree stability. Computer-derived volumes from root segments of 29 trees were compared to volumes of the same roots derived from water displacement. A strong linear relationship was observed between the volumes derived by these two methods (adjusted R 2 = 0.97) with 3-D Imaging Technologies to Measure Root Volume • 333 an RMSE of 40.37 cm 3 (12.3%) and a bias of 17.2 cm 3 (5.3%). Using the final computer models to assess root architecture, we found the most significant factors affecting tree stability were 1) root volume in the top 10 cm of the soil in a 90° wedge on the side opposite of the pull direction, 2) roots located 40 to 50 cm deep in a 90° wedge on the side opposite of the pull direction, and 3) roots located deeper than 60 cm in a 90° wedge on the side opposite of the pull direction (final model: P-value < 0.0001, adjusted R 2 = 0.7854). Planting depth did appear to impact architecture (and ultimately stability) in our study, with deeply planted trees having fewer roots in the top 10 cm of soil and more roots located 40 to 50 cm deep. Given these findings, we propose that the methods employed have the potential to advance knowledge in future studies on whole-tree stability.
Article
Full-text available
The physical, chemical, and biological constraints of urban soils often pose limitations for the growth of tree roots. An understanding of the interrelationships of soil properties is important for proper management. As a result of the interdependence of soil properties, the status of one soil factor can have an effect on all others. Preventing soil damage is most effective and preferred. Cultural practices, such as cultivation and mulching, can be effective in improving soil properties. Soil additives, such as biostimulant products, have not proven to be consistently effective through research. The management challenge is to provide an urban environment that functions like the natural environment.
Article
Full-text available
This paper evaluated the feasibility of a terrestrial point cloud generated utilizing an uncalibrated hand-held consumer camera at a plot level and measuring the plot at an individual-tree level. Individual tree stems in the plot were detected and modeled from the image-based point cloud, and the diameter-at-breast-height (DBH) of each tree was estimated. The detected-results were compared with field measurements and with those derived from the single-scan terrestrial laser scanning (TLS) data. The experiment showed that the mapping accuracy was 88% and the root mean squared error of DBH estimates of individual trees was 2.39 cm, which is acceptable for practical applications and was similar to the results achieved using TLS. The main advantages of the image-based point cloud data lie in the low cost of the equipment required for the data collection, the simple and fast field measurements and the automated data processing, which may be interesting and important for certain applications, such as field inventories by landowners who do not have supports from external experts. The disadvantages of the image-based point cloud data include the limited capability of mapping small trees and complex forest stands.
Article
Full-text available
Root growth potential (RGP) measurement can be time­ consuming and tedious, especially when seedlings have fibrous root systems. A volume-displacement technique involving suspending seedling roots and shoots in a clear plastic tube allows rapid estimation of the volume of plant parts while minimizing gravimetric errors. The technique was tested in three experiments examining (1) the repeat­ ability of the technique, (2) its usefulness in estimating RGP, and (3) the relationship ofvolume displacement to tissue dry weight. Results indicate that this technique provides a quick, reproducible measure ofseedling size while allowing a rapid (2-seedlings-per-minute) assay ofRGP in container-grown stock. Tree Planters' Notes 45(3): 121-124; 1994. Seedling morphological attributes have been used extensively in reforestation research to assess seedling performance potential and to explain outplanting performance (Mexal and South 1990, Mexal and Landis 1990). Nondestructive measures of seedling morphol­ ogy allow for measurement of the entire test popula­ tion. This increases the sensitivity of analysis by eliminating the need for subsampling. Traditional nondestructive measures include seedling height, root collar diameter, and (occasionally) total seedling fresh weight. In addition to pre;viding these measures, volume displacement analysis allows total biomass to be subdivided into shoot and root volume. Volume displacement analysis provides sensitive and repeat­ able morphological information that may be useful in physiological analysis of seedling performance poten­ tial (for example, in root growth potential analysis) (Burdette 1979). There are two approaches to volume displacement analysis. The first approach, actual volume displace­ ment, measures the volume of water displaced when plant tissue is submerged in a vessel of water (Novo­ selov 1960). The second is a gravimetric approach based on Archimedes' principle, which states that"a body wholly or partly immersed in a fluid is buoyed up by a force equal to the weight of the fluid dis­ placed" (Weast 1980). In the gravimetric approach, change in weight is used as the estimate of plant volume. A system for using gravimetric volume displacement is described below (see Materials and Methods). Volume displacement analysis has the advantage of providing a fast measure of new root production (Burdette 1979). In addition, its nondestructive nature permits repeated measures over time. However, previously published volume displacement techniques have serious limitations. First, techniques that measure actual volume displaced require elaborate glassware configurations if they are to be sensitive enough to detect slight differences in seedling stock. Second, most gravimetric approaches require balancing the seedling in the water vessel at a specified point on the seedling so that plant tissue submerged in the water does not touch vessel walls (Burdette 1979). If the plant touches the container wall, the balance may fail to provide a steady reading, or the plant's frictional resistance may cause tissue volume to be underesti­ mated. Any slight adjustment in holding the seedling may produce erroneous measures, compromising the accuracy and repeatability of the experiment. In three experiments, a technique was tested for determining plant part volume and for quantifying new root production. This technique was designed to be simple and repeatable, using common laboratory equipment.
Article
Full-text available
Recent research has improved our understanding of how structural roots of landscape trees respond to being located abnormally deep in the soil profile. This condition is widespread among landscape trees and may originate during nursery production, at transplanting into the landscape, or when construction fill or sediment deposits bury root systems of established trees. Deep structural roots sometimes hinder successful establishment of trees, occasionally enhance establishment, and often have little or no effect on growth or survival. When trees respond to deep structural roots, effects are sometimes observed when root collars are as little as 7.5 cm (3 in) deep. In some cases, deep structural roots are implicated in girdling root formation, but research in this area is quite limited. This review describes scientific progress in our understanding of deep structural roots and encompasses their history, causes, and significance, as well as interdisciplinary efforts to address deep planting and tree response during establishment to deep structural roots. A theoretical model of short-term tree response to deep structural roots is presented that helps explain these conflicting outcomes and provides a decision framework for practitioners evaluating trees with deep structural roots.
Article
Full-text available
Tree transplanting practices influence plant survival, establishment, and subsequent landscape value. The inability to adequately quantify effects of transplanting practices threatens long-term sustainability of landscape trees. Planting depth [i.e., location of the root collar relative to soil grade (soil surface)], is of particular concern for tree growth, development, and landscape performance. The authors of this study investigated the effects of planting depth and transplant season on landscape establishment of baldcypress [Taxodium distichum (L.) Rich.] and effects of planting depth and irrigation practices on landscape establishment of sycamore (Platanus occidentalis L.). Baldcypress planted above grade had reduced relative growth rate in height and diameter compared to those planted at or below grade during the first growing season, regardless of transplant season. Sycamore trees planted below grade had increased mortality and decreased growth compared to trees planted at grade or above grade, regardless of irrigation treatment. Even though trees of both species were grown under similar conditions, baldcypress was much more tolerant to belowgrade planting than sycamore. We suggest that this is related to the native habitat of both species, where baldcypress is frequently exposed to hypoxic conditions while sycamore is more prevalent on well-drained soils. Thus, it may be important to consider the native habitat of a species when evaluating the effect of planting depth.
Article
Full-text available
The relationship between the anchorage mechanics and root architecture of Pinus peuce was investigated by carrying out winching tests and examining excavated root systems of 20 mature trees. The root system was dominated by 6.1±1.3 lateral roots, more than 70% of the lateral root cross sectional area (CSA) being distributed in the uppermost 10 cm of soil. Anchorage strength was related to the size of the tree and CSA. The overturning moment of trees was proportional to the diameter at breast height (DBH) to the power of 1.6. The trees exhibited significant asymmetry in anchorage rigidity, but although there was clustering of lateral roots in a preferred direction the root asymmetry was not significantly correlated with the asymmetry in anchorage rigidity, suggesting that much of the anchorage is provided by tap and sinker roots, rather than the laterals. However, the major laterals showed dorsoventral eccentricity, the more eccentric ones being those that were distributed closer to the soil surface and which pointed perpendicular to the direction of greatest resistance. This suggests that this is a result of thigmomorphogenetic effects. These results are compared with those for the related P. sylvestris and suggest that the assimilation and anchorage characteristics of root systems are controlled independently of each other.
Article
Full-text available
Two root-pruning methods simulated construction-related trenching and individual root cuts such as from decay after root pruning. Tree trunks were pulled to an angle of 1° from vertical using measured force. A third of the study trees were pulled to failure to determine the relationship between the 1° pull force and the pull-to-failure force. The regression had correlation with r 2 equal to 0.76. Utility trenching was simulated with linear cuts across the root zone. Measurable decreases in force applied occurred when cuts were within three times the trunk diameter from the trunk. Force decreased by 35% when a tangential cut was made at the trunk. When individual roots were severed, the pull force was reduced with each root cut. When one root was severed, the decrease in force averaged 12%; when half of the exposed buttress roots were severed, the decrease was 30%. Arborists should avoid cutting any tree roots near the trunk. Linear trenching should not be closer to the trunk than a distance equal to or greater than three times the trunk diameter.
Article
Full-text available
A database was constructed of tree-anchorage measurements from almost 2000 trees from 12 conifer species that were mechanically overturned on 34 sites in the United Kingdom between 1960 and 2000. Anchorage was compared among species, soil groups (freely-draining mineral, gleyed mineral, peaty mineral, and deep peat) and root depth classes (shallow, <40 cm; medium, 40–80 cm; and deep, >80 cm) using regressions of critical turning moment against stem mass. Sitka spruce (Picea sitchensis (Bong.) Carr.) was used as a benchmark because it formed the largest part of the database and was the only species with all soil-group and depth-class combinations. Anchorage of Sitka spruce was strongest on peat and poorest on gleyed mineral soils. Deep rooting increased critical turning moments by 10%–15% compared with trees of equivalent mass with shallower roots. Significantly better anchorage than Sitka spruce was found for grand fir (Abies grandis (Dougl. ex D. Don) Lindl.), with various rooting depths on freely draining and gleyed mineral soils and for Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) on medium-depth mineral soil. Lodgepole pine (Pinus contorta Dougl. ex Loud.) had poorer anchorage than Sitka spruce over a range of soil groups and root depth classes. Norway spruce (Picea abies (L.) Karst.) on shallow gleyed mineral soil, and Corsican pine (Pinus nigra subsp. laricio (Poir.) Maire) on medium depth mineral soil, also had poorer anchorage. Other combinations had similar anchorage to the equivalent Sitka spruce. These results are discussed with respect to the development of forest wind-risk models.
Article
Full-text available
Overturning bending moments were analysed for Pinus radiata D. Don trees which had been winched over at Eyrewell Forest, Canterbury, between 1967 and 1971. Trees were sampled from four different age-classes in three forest compartments. The bending moment applied by the winch and cable system increased rapidly and linearly to a maximum value before decreasing until the trees toppled under their own weight. The bending moment due to the mass of the offset stem plus crown contributed an average of 9% to the total overturning moment at the point of maximum applied moment. Significant positive relationships were found between the maximum resistive bending moment (M c) offered by the tree and its total height, diameter at breast height (dbh), and stem volume. The greatest proportion of the variance in M c was explained by a linear relationship involving dbh. The angle of stem deflection at both the maximum resistive bending moment and the point at which the tree toppled under its own weight was significantly and negatively related to tree height. Analyses of covariance found that root plate diameter had a significant effect on M c while root plate depth did not. The effect of taper was uncertain.
Article
Full-text available
The stability of shallowly rooted trees can be strongly influenced by the symmetry of the ‘structural’ system of woody roots. Root systems of forest trees are often markedly asymmetric, and many of the factors affecting symmetry, including root initiation and the growth of primary and woody roots, are poorly understood. The internal and environmental factors that control the development, with respect to symmetry and rigidity, of shallow structural root systems are reviewed and discussed with particular reference to Sitka spruce (Picea sitchensis Bong. Carr.). Areas where there is insufficient knowledge are highlighted. A scheme is proposed that represents the root system as a set of spokes that are variable in number, size and radial distribution. Rigidity can vary between and along each of the spokes. The root system is presented as a zone of competition for assimilates, where allocation to individual roots depends upon their position and local variations in conditions. Factors considered include the production of root primordia of different sizes, effects of soil conditions such as the supply of mineral nutrients and water on growth of primary and woody roots, and the effect of forces caused by wind action on growth of the cambium, giving rise to roots which, in cross section, resemble I- or T-beams, and efficiently resist bending.
Article
Full-text available
Wind damage in Japan is mainly caused by typhoons (i.e., tropical cyclones), which are characterized by intensive heavy rainfall and strong winds. In this study, we conducted tree-pulling experiments on two sites to find out whether rapidly supplied water on the soil would affect stability of root anchorage of hinoki (Chamaecyparis obtuse (Sieb. Et Zucc.) Endl.), as expected. For the experiments, we first supplied several quantities of water around the target trees, and then they were pulled down using a wire winch. On study site 1 (Kamiatago experimental forest), we applied general tree-pulling experiments (no water supply) in 2008 and six different irrigation treatments around the target trees in 2009. On study site 2 (Chiyoda experimental forest), we applied one irrigation treatment in 2009. As a result, five trees were uprooted and two were broken in 2008, and all nine trees were uprooted in 2009 on study site 1, regardless of irrigation treatment. On study site 2, two trees pulled down after 4h of water supply were ruptured at the stem base, opposite to two trees pulled down immediately after supplying water. The water content below the root plate significantly affected root anchorage and more specifically, the maximum turning moment, stem angle at the maximum force, and stiffness index. Moreover, water inside the root plate increased root anchorage at the beginning of a tree failure process. However, it also reduced the root plate area of the hinge side. Conversely, high water content below the root plate decreased root anchorage. KeywordsTree-pulling experiments–Wind damage–Root anchorage–Water content in the soil
Article
Full-text available
Eugenia grandis (Wight) is grown in urban environments throughout Malaysia and root systems are often damaged through trenching for the laying down of roads and utilities. We investigated the effect of root cutting through trenching on the biomechanics of mature E. grandis. The force necessary to winch trees 0.2m from the vertical was measured. Trenches were then dug at different distances (1.5, 1.0 and 0.5m) from the trunk on the tension side of groups of trees. Each tree was winched sideways again and the uprooting force recorded. No trenches were made in a control group of trees which were winched until failure occurred. Critical turning moment (TMcrit) and tree anchorage rotational stiffness (TARS) before and after trenching were calculated. Root systems were extracted for architectural analysis and relationships between architectural parameters and TMcrit and TARS were investigated. No differences were found between TMcrit and trenching distance. However, in control trees and trees with roots cut at 1.5m, significant relationships did exist between both TMcrit and TARS with stem dimensions, rooting depth and root plate size. TARS was significantly decreased when roots were cut at 0.5m only. Surprisingly, no relationships existed between TMcrit and TARS with any root system parameter when trenching was carried out at 0.5 or 1.0m. Our study showed that in terms of TARS and TMcrit, mechanical stability was not greatly affected by trenching, probably because rooting depth close to the trunk was a major component of anchorage.
Article
Full-text available
In numerous studies dealing with roots of woody plants, a description of the root system architecture is needed. During the twentieth century, several manual measurement methods were used, depending on the objectives of study. Due to the difficulties in accessing the roots and the duration of measurements, the studies generally involved a low number of root systems, were often qualitative and focused only on one specific application. Quantitative methods in plant architecture were largely developed in the last 40years for aerial architecture. However, root systems have particular features and often need specific procedures. Since the end of the 1990s, new devices and techniques have been available for coarse root architecture measurements including volume location techniques (non-invasive or destructive) and manual or semi-automatic 3D digitising. Full 3D root system architecture dynamics was also reconstructed from partial measurements using modelling procedures. On the one hand, non-invasive and automatic techniques need more development to obtain full 3D architecture, i.e. geometry and topology. On the other hand, both one inexpensive manual and one semi-automatic digitizing procedure are now available to measure precisely and rapidly the full 3D architecture of uprooted and excavated coarse root systems. Specific software and a large number of functions are also available for an in-depth analysis of root architecture and have already been used in a dozen of research papers including a fairly large sample of mature trees. A comprehensive analysis of root architecture can be achieved by classifying individual roots in several root types through architectural analysis. The objective of this paper is both to give a detailed overview of the state of the art techniques for 3D root system architecture measurement and analysis and to give examples of applications in this field. Practical details are also given so that this paper can be used as a sort of manual for people who want to improve their practice or to enter this quite new research field.
Article
Full-text available
Wind affects the structure and functioning of a forest ecosystem continuously and may cause significant economic loss in managed forests by reducing the yield of recoverable timber, increasing the cost of unscheduled thinning and clear-cuttings, and creating problems in forestry planning. Furthermore, broken and uprooted trees within the forest are subject to insect attack and may provide a suitable breeding substrate, endangering the remaining trees. Therefore, an improved understanding of the processes behind the occurrence of wind-induced damage is of interest to many forest ecologists, but may also help managers of forest resources to make appropriate management decisions related to risk management. Using fundamental physics, empirical experiments, and mechanistic model-based approaches in interaction, we can study the susceptibility of tree stands to wind damage as affected by the wind and site and tree/stand characteristics and management. Such studies are not possible based on statistical approaches alone, which are not able to define the causal links between tree parameters and susceptibility to wind damage. The aim of this paper is to review the recent work done related to tree-pulling and wind tunnel experiments and mechanistic modeling approaches to increase our understanding of the mechanical stability of trees under static loading.
Article
Quercus virginiana Mill. Highrise® were planted into 10 L and then 57 L plastic nursery containers at two depths for a total of four depth combinations, and then root pruned in one of three different manners when planted into the landscape. Nursery planting depth had no impact on growth in the nursery or bending moment required to tilt trunks in the first two years following landscape planting. Root pruning when planting into landscape by either method tested had no effect on growth the first two years. Number of roots circling inside the root ball was reduced by shaving or deep root ball slicing two growing seasons after planting. Root balls that were either sliced or shaved generated more roots in landscape soil one growing season after landscape planting than those that were not root pruned, which probably explained the greater bending moment required to pull trees out of the ground. Total cross-sectional root area one growing season after landscape planting was greater on shaved trees than those not root pruned at planting. Bending moment at 20 degrees trunk tilt was best correlated with cross sectional area of roots growing straight across the periphery of the root ball and into landscape soil.
Article
Deciduous trees in Ohio were surveyed before harvest (seven nurseries) and after harvest (eight brokerage facilities) to determine the depth of their main lateral roots. Main lateral roots originate at the root-shoot junction in trees and are also referred to as the root flare or buttress roots. In the nursery survey, differences in the depth of main lateral roots were found among nurseries and production year with main lateral roots an average of 6.1 cm (2.4 in) deep in the soil profile. From the broker survey, both brokers and propagation methods showed differences in depth with an average of 8.6 cm (3.4 in) of excess soil over the main lateral roots. The main lateral roots for most trees were greater than 2.5 cm (1 in) in depth which was deeper than industry standards allow.
Article
After 40 months in air root pruning containers, Quercus virginiana ‘SDLN’ Cathedral Oak® live oak planted 3.8 and 8.9 cm (1.5 and 3.5 in) deep from rooted cuttings had greater caliper than trees planted at 1.3 cm (0.5 in) below substrate surface. Trees in the 1.3 cm (0.5 in) deep treatment grew taller than all other trees except for those in the 3.8 cm (1.5 in) deep treatment. Most (80%) trees were graded as culls according to root evaluations in the Florida Grades and Standards for Nursery Stock. This resulted mostly from roots circling and crossing the top of the root ball in the #3 and/or #15 container sizes. Trees planted 6.4 cm (2.5 in) deep in #3s, then 6.4 cm deep in #15s, and 6.4 cm deep in #45s [19 cm (7.5 in) total depth] had fewer, smaller diameter, and deeper primary roots than trees planted at all other depths. The presence of a trunk flare and surface roots decreased with increasing planting depth indicating that these could be used as an indicator of primary root depth. Cathedral Oak® demonstrated the capacity to generate new roots above the primary flare roots only when rooted cuttings were planted into #3 containers. Trees adjusted their root systems by generating a new set of roots along the buried stem up to the substrate surface. Roots did not grow from the buried portion of the stem when trees in #3 containers were planted 6.4 cm (2.5 in) deep into #15 containers. In other words 75% or more of the primary structural roots were deflected by either the #3 or #15 container wall or both, indicating that most primary roots that emerged from the trunk did so when the tree was in the #3 or #15 container within 22 months of planting from rooted cuttings. Roots often grafted when crossed or laid against other roots, but roots did not graft to trunks.
Article
Trees with root systems established well below grade due to deep planting or soil disturbance are common in urban landscapes, yet the long term effects of buried trunks and subsequent remediation strategies, such as root collar excavation are poorly documented. We evaluated the consequences of deep planting over a 10-year period on tree growth and stability, with and without root collar excavation, for red maple [Acer rubrum L. Red Sunset® (‘Franksred’)] and Northern red oak (Quercus rubra L.) planted at grade or 30-cm below grade. Sleeves to prevent soil-trunk contact were installed around trunks on a subset of deep trees. Root collar excavations were made during the 6th growing season for both species and trees were grown for an additional 4 and 3 growing seasons for red maples and Northern red oaks, respectively. Within two weeks of root collar excavations, pulling tests compared the effect of treatments on stability of red maples. Deep planting generally slowed growth of red maple but had no clear effect on Northern red oak. Root collar excavation had no lasting effect on growth of either species. Approximately 55% of deep red maples and 33% of deep Northern red oaks had roots crossing and in intimate contact with buried trunks, suggesting a potential for future girdling roots. Approximately 25% of deep maples had substantial adventitious rooting. All deep Northern red oaks had new roots emerging just above the first original structural roots but none were clearly adventitious. Trunk sleeves had no effect on growth for either species. Neither deep planting nor root collar excavation resulted in a loss of tree stability compared to trees planted at grade, although failure patterns varied among treatments. Overall, the biggest long term concern for deep-planted trees is the potential for girdling root formation.
Article
Urban land development frequently destroys soil structure and removes organic matter, limiting tree growth. Soil rehabilitation has potential to improve soil quality but the long-term effectiveness and consequences for tree growth are poorly documented. We evaluated growth, canopy development, and physiological response of five tree species over six years to soil rehabilitation in an experimental site pre-treated to replicate typical land development. A corollary experiment evaluated growth and establishment of three additional species one year after rehabilitation in highly urbanized sites in Arlington County, Virginia. Plot study soil treatments were: typical practice (TP) (10 cm topsoil replaced); enhanced topsoil (ET) (topsoil + rototilling); profile rebuilding (SPR) (compost amendment via subsoiling to 60-cm depth + topsoil + rototilling); and undisturbed (UN) (agricultural land with no pre-treatment). In Arlington, SPR was compared with conventional site preparation (topsoil replacement). Overall, trees grew more rapidly in SPR soils and soil depths immediately below the surface (∼15-30 cm) were most affected by SPR, which reduced soil bulk density between 0.19 and 0.57 Mg m−3 compared to nonrehabilitated soils. After six years, both trunk cross-sectional area and canopy area of plot-study trees in SPR soils matched or surpassed those in undisturbed soil for all species except Q. bicolor while canopy area increased by as little as 2% (Q. bicolor) to as much as 84% (U. ‘Morton’). In Arlington, SPR resulted in 77% trunk cross-sectional area growth after one year. Plant and soil water relations may also be altered by rehabilitation, possibly contributing to its potential as a tool for stormwater mitigation. Rehabilitation accelerates establishment and growth of urban trees planted in compacted urban soils indicating that the below-ground environment should be a key component in policy and decision making.
Article
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 landscape 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.
Article
Mature pygmy date palms ( Phoenix roebelenii O'Brien) having a minimum of 90 cm of clear trunk were transplanted into a field nursery at their original depth or with 15, 30, 60, or 90 cm of soil above the original rootball. Palms planted at the original level or with the visible portion of the root initiation zone buried had the largest canopies, highest survival rates, and lowest incidence of Mn deficiency 15 months after transplanting. Palms planted 90 cm deep had only a 40% survival rate, with small, Mn-deficient canopies on surviving palms. Palms whose original rootballs were planted 90 cm deep had very poor or no root growth at any level, but had elevated Fe levels in the foliage. None of the deeply planted palms produced any new adventitious roots higher than 15 cm above the visible portion of the root initiation zone.
Article
Urban trees are frequently planted with their root collars and structural roots buried well below soil grade, either because of planting practices, nursery production practices, or both. These deeply planted structural roots can impair tree establishment and are thought to reduce tree growth, lifespan, and stability, although research has provided few and contradictory results on these questions to date. This study examines container-grown (55L) Turkish hazel trees (Corylus colurna L.), planted either at grade, 15cm below grade, or 30cm below grade into a well-drained silt loam soil, over nearly 8 years. Five years after planting, in 2004, remediation treatments (root collar excavations) were performed on two replicates of each below-ground treatment. Subsequently, all trees were subjected to flooding stress by being irrigated to soil saturation for approximately 6 weeks. In 2006, flooding stress was repeated. Trees root systems were partially excavated in 2007, and root architecture was characterized. Deep planting did not affect trunk diameter growth over 8 years. Survival was 100% for the first 5 years; however, one 30cm below grade tree died after flooding in 2004 and another died after the 2006 flooding. Photosynthesis was monitored during the 2004 flooding and all trees experienced decline in photosynthetic rates. There was an apparent slight delay in the decline for trees with excavated root collars and those planted at grade. Girdling roots reduced trunk taper and occurred primarily on unremediated trees planted 30cm below grade.Selected individual roots were excavated and followed from the root ball and were observed to gradually rise to the upper soil regions. Analysis of roots emerging from excavation trench faces indicated that vertical root distribution at approximately 1.25m from the tree trunks was the same regardless of planting depth. Longterm consequences of planting below grade are discussed.
Article
Planting depth and irrigation can impact root and trunk growth following landscape installation in various soil types; however, impact on lateral tree stability is unknown. Quercus virginiana Mill. trees were installed at four landscape planting depths into a well drained sandy soil and grown for six years under two irrigation regimes. There was no impact of planting depth on trunk diameter or height in the first five growing seasons after planting; however, trees irrigated regularly had 10mm larger trunk diameter than trees not irrigated. There was no impact of planting depth or irrigation on bending stress required to tilt trunks to 1°, 2° and 5° from vertical non-deformed start position six growing seasons after planting. Planting depth and irrigation also had no effect on diameter of the ten largest roots to a soil depth of 122cm, which might explain why bending stress required to pull trees was similar for all planting depth and irrigation treatments. However, trees planted deeper had deeper roots measured 115cm horizontally from trunk. Root cross-sectional area (CSA) 20–30 and 40–50cm deep was positively correlated with bending stress six growing seasons after planting. Trees planted deep had some roots that ascended toward soil surface at a steeper angle than trees planted shallow, and had a deeper root flare and more roots growing over the flare that could potentially form stem girdling roots. Diameter of roots over the flare was not impacted by planting depth; however, trees irrigated for the duration of the study had more roots over main flare roots than trees not irrigated. Irrigation increased root number (>5mm diameter) in the top 30cm soil profile. Irrigation had no impact on any other measured root parameter. Trees planted deeper settled down below soil surface more than shallow planted trees.
Article
The effect of planting depth, defined as the location of the root collar relative to soil surface, is of particular concern for tree growth, development, and performance in the landscape and seems to be dependent on soil conditions. The objective of this study was to determine the effect of three planting depths and four soil amendments on live oak (Quercus virginiana Mill.) growth and visual quality. Trees were planted with root collars at one of three planting depths (grade, 7.6. cm above grade, or 7.6. cm below grade). Soil amendments were: incorporated sand (30% by volume), incorporated composted peat (30% by volume), sandy topsoil in raised (20. cm) bed, and native sandy loam soil (control). Planting at grade or below grade resulted in 0% mortality, while planting live oak trees above grade resulted in 12.5% mortality. The container produced trees were top-heavy (high shoot:root ratio) and were thus susceptible to wind damage when planted above grade. Trunk diameter growth and relative growth rate were smaller when trees were planted with root collars below grade compared to those planted above grade or at grade. Visual quality of live oak roots was improved when trees were planted in raised beds with sandy topsoil compared to the control soil. Shoot visual quality was improved when trees were planted in the incorporated sand and raised beds with sandy topsoil compared to the control and incorporated peat sections. Thus, it is recommended to plant live oaks with the root collar at grade and in sandy top soils in raised beds to improve tree quality after establishment. © 2011 Elsevier GmbH.
Article
Tree-pulling experiments were conducted in Singapore involving 20 rain trees (Samanea saman) growing in four different soil types (1) structural soil with 80% granite chips and 20% sandy loam soil, (2) structural soil with 50% granite chips and 50% sandy loam soil, (3) in situ soil and (4) top soil. The trees were pulled over with a winch attached to the stem at a standard height of 1.3m and the force required to uproot or break the trees were recorded. The physical above and below ground characteristics of the trees were also measured. All 20 trees in this study failed via uprooting without any stem fracture. Analysis of the data showed that the maximum resistive bending moment (BMmax) was positively correlated with the overall size of the root plate, the size (diameter) of the individual roots and the extent of crown spread. The dry mass of crown was significantly greater in the 80:20 structural soil treatment while no significant difference was found between the other soil types. The trunk diameter was not significantly different between treatments. Significant differences were observed in the depth of root plates where those grown in top soil had significantly deeper root plates as opposed to the other treatments but though deeper, the vast majority of trees planted in top soil exhibited fibrous rather than structural roots. The cross-sectional area of roots which is indicative of the size of the individual roots showed a significantly greater value in the 80:20 structural treatment while the 50:50 structural and top soil treatments had the lowest values. Significant differences in BMmax were only observed in the in situ soil type while the rest of the planting substrates exhibited values that were comparable and not significantly different. KeywordsStructural soil-Tree pulling-Foliar characteristics-Root plate characteristics-Tree stability
A numerical investigation into the influence of soil type and root architecture on tree anchorage
  • L Dupuy
  • T Fourcaud
  • A Stokes
Dupuy, L., T. Fourcaud, and A. Stokes. 2005. A numerical investigation into the influence of soil type and root architecture on tree anchorage. Plant and Soil 278: 119-134.
Planting depth and the growth of nursery trees
  • M Jarecki
  • D Williams
  • G Kling
Jarecki, M., D. Williams, and G. Kling. 2005. Planting depth and the growth of nursery trees. pp. 11-16. In: Proceedings of Trees and Planting: Getting the Roots Right. The Morton Arboretum, Lisle, Illinois, U.S.A..