Land development restricts tree growth by damaging soil structure and removing organic matter. Mechanical loosening and organic amendment may improve soil physical properties and tree establishment and growth. Effects of typical post-construction practice and improved methods of soil restoration on tree growth and soil properties were evaluated over two years. Treatments included undisturbed soil (UN); minimum effort (ME) (10 cm topsoil); enhanced topsoil (ET) (ME + rototilling); and profile rebuilding (PR) (compost, subsoiling, topsoil and rototilling). Pretreatment included removing topsoil and compacting subsoil to 1.95 g/cm3 bulk density. Acer rubrum L. (red maple), Quercus bicolor Willd. (swamp white oak), Ulmus 'Morton' (Ulmus japonica (Rehd.) Sarg. x Ulmus wilsoniana Schneid.) (Accolade® elm), Prunus 'First Lady' (Prunus xincam x Prunus campanulata) L. and Quercus macrocarpa Michx. (bur oak) were planted in each plot. The PR treatment reduced soil bulk density at 15-20 cm depth and increased soil C/N ratio, pH, and CEC. Mean canopy projection and cross-sectional trunk area in PR plots ranged from 32% to 226% and 16% to 71% greater, respectively, than those in ME plots. PR treatment increased Q. bicolor photosynthesis rates. Greater root presence was observed in deeper soil layers of ET and PR treatments for A. rubrum and of UN and PR for Q. bicolor; root distribution was not measured for other species. Rehabilitation improved soil physical properties and tree growth after two years. Species variation in growth rate and environmental tolerance appeared to influence early growth treatment effects. Long-term data is needed to fully understand effects of soil rehabilitation. / Master of Science

Root biomass accounts for about 25% of the carbon storage in mid-latitude forests. Estimation of root biomass for carbon cycling studies requires either direct measurement by excavation of root systems, or remote measurement using ground penetrating radar (GPR) or other geophysical methods. This study evaluated the ability of a 2-GHz multi-channel GPR system (IDS Hi-BrigHT) to detect and map white pine roots in managed forest near Turkey Point, southern Ontario. The GPR system employed eight dual-polarized antenna pairs separated at 10 cm intervals. GPR data were acquired as overlapping swaths (2 cm line spacing, 0.4 cm inline) across a 25-m2 test site (TP74-R) containing a juvenile white pine tree. Radargrams were processed to full 3-D radar volumes for time slicing and interpretation of root architecture and comparison with the excavated root network. Radargram signal processing was successful in suppressing airwave and other background noise and improved the detection of root diffractions on radargrams. The majority of roots were found in the rooting zone at a depth of 5-40 cm. Roots as small as 0.5 cm were detected with the 2-GHz frequency, but many roots <1.5 cm diameter could not be detected as continuous root structures. Root detection was strongly dependent on root orientation; large, coarse roots (>3-5 cm) were imaged as continuous root segments when oriented perpendicular to GPR profiles. Roots intersecting GPR profiles at angles <30-45 degrees were either imaged incompletely or not detected on radargrams. The highest rate of root detection was achieved with horizontally polarized (HH) antennas (dipole axis parallel with the root structures). Isosurface root models constructed from the Hilbert-transformed radargrams allowed mapping of the 3-D dimensional root architecture for large (> 3-5 cm diameter) roots. Isosurface models provide a means for estimating the coarse root volume for large roots and could be employed in future work to monitor temporal changes in root biomass by repeat survey at the same measurement site. Radargram signal processing was successful in suppressing airwave and other background noise and improved the detection of root diffractions on radargrams. The majority of roots were found in the rooting zone at a depth of 5-40 cm. Roots as small as 0.5 cm were detected with the 2-GHz frequency, but many roots <1.5 cm diameter could not be detected as continuous root structures. Many roots were not detected due to dependence of root reflection amplitude on root orientation. Roots oriented at >30-45 degrees to the survey swaths were imaged incompletely or not detected. Most large coarse roots (>5 cm diameter) were mapped as continuous structures when the root orientation was either parallel to, or perpendicular to the GPR transects. The highest rate of root detection was achieved with the horizontally polarized (HH) antennas, with the dipole axis perpendicular to the root structures. Isosurface root models constructed from the Hilbert-transformed radargrams allowed mapping of the 3-D dimensional root architecture for large (> 3-5 cm diameter) roots. The isosurface models provide a means for estimating the coarse volume and belowground biomass but further work is required to improve 3-D image resolution to allow detection of the entire root network. The method could be employed to measure the temporal changes in root biomass by conducting repeat surveys at the same measurement site. Radargram signal processing was successful in suppressing airwave and other background noise and improved the detection of root diffractions on radargrams. The majority of roots were found above a depth of 40 cm with the root zone being detected at a depth of10-15 cm. Roots as small as 0.5 cm were detected with the 2-GHz frequency, but many roots <1.5 cm diameter could not be detected as continuous root structures. Many roots were not detected due to dependence of root reflection amplitude on root orientation. Roots oriented at >30-45 degrees to the survey swaths were imaged incompletely or not detected. Most large coarse roots (>5 cm diameter) were mapped as continuous structures when the root orientation was either parallel to, or perpendicular to the GPR transects. The highest rate of root detection was achieved with the horizontally polarized (HH) antennas, with the dipole axis perpendicular to the root structures. Isosurface root models constructed from the Hilbert-transformed radargrams allowed mapping of the 3-D dimensional root architecture for large (> 3-5 cm diameter) roots. The isosurface models provide a means for estimating the coarse volume and belowground biomass but further work is required to improve 3-D image resolution to allow detection of the entire root network. / Thesis / Master of Science (MSc) / Forests play an important role in the global carbon cycle by removing carbon from the Earth’s atmosphere and storing it in tree tissues as biomass. Estimation of the amount of biomass and carbon stored in forests is critical to predictive climate change models, and increasingly employs remote sensing methods to detect both the above ground biomass (e.g. leaves, tree branches) and the belowground carbon in the tree root system. Measurement of the belowground biomass is most difficult, as it cannot be directly observed without destructive excavation of the tree root system. This study investigated the application of new technology, multi-channel ground penetrating radar (GPR), for mapping tree root systems. The GPR system (IDS Hi-BrigHT) employs ‘swath mapping’ using high frequency pulsed radio waves and multiple transmitting and receiving antennas to produce detailed maps of roots structure. The GPR capabilities were evaluated at a test site at the Turkey Point Flux Station (TPFS) in southern Ontario. The root system of a juvenile white pine tree (20-30 cm diameter) was swath mapped over a 25-m2 area with a line spacing of 2 cm. The GPR data were processed to produce a 3-dimensional radar volume, which can be ‘sliced’ in various orientations to reveal the root structure. The time slice maps show that roots as small as 1-cm can be detected and roots larger than 3 cm in diameter can be mapped as continuous root segments.

Shallow foundations rested on Leda clay that are widely distributed in Eastern Canada exhibit shrinkage characteristics and are prone to differential settlements. Due to this reason, significant repairs are necessary to the foundations and basements of residential structures constructed in Leda clay deposits. Differential settlements are commonly attributed to the changes in the natural water content of soils associated with water infiltration, evaporation or plant transpiration (i.e., tree-roots-suction). Various research studies have been undertaken to estimate the possible settlements of shallow foundations associated with the water infiltration or evaporation. Several thumb rules have been proposed through research studies, providing recommendations with respect to the distance at which trees must be planted as a function of their heights at maturity such that differential settlements can be avoided. However, limited studies have been carried out to estimate or model the settlements of shallow foundations taking into account the influence of tree-roots-suction. In the present research program, a comprehensive experimental study regarding the deformation characteristics of a sandy loam soil from Ottawa due to tree-root-suction is undertaken, using specially designed equipment. The study has been undertaken using a sandy loam soil so that the testing program can be conducted in a shorter period of time. An artificial rooting system (ARS) was designed and placed in a specially designed tank at the University of Ottawa to simulate tree-roots-suction and measure soil surface settlements associated with a decrease in natural water content (or increase in soil suction) using particle image velocimetry (PIV) technique. The ARS consists of an artificial root, suction generator, matric suction and volumetric water content monitoring devices. The variation of matric suction and volumetric water content are monitored at various depths using the instrumentation of the ARS. Based on the results of the experimental studies, a methodology is proposed to model the settlement behaviour of sandy loam soils due to suction from ARS, using commercial finite element software, SEEP/W and SIGMA/W (i.e. software package of GeoStudio 2007). The study offers a reasonably good comparison between the measured surface settlements and those estimated using the finite element modelling analysis. The modelling methodology presented in this thesis is promising and may be extended for estimating the settlement behaviour associated with the tree roots suction of Leda clay deposits and to other soils.

Shallow foundations rested on Leda clay that are widely distributed in Eastern Canada exhibit shrinkage characteristics and are prone to differential settlements. Due to this reason, significant repairs are necessary to the foundations and basements of residential structures constructed in Leda clay deposits. Differential settlements are commonly attributed to the changes in the natural water content of soils associated with water infiltration, evaporation or plant transpiration (i.e., tree-roots-suction). Various research studies have been undertaken to estimate the possible settlements of shallow foundations associated with the water infiltration or evaporation. Several thumb rules have been proposed through research studies, providing recommendations with respect to the distance at which trees must be planted as a function of their heights at maturity such that differential settlements can be avoided. However, limited studies have been carried out to estimate or model the settlements of shallow foundations taking into account the influence of tree-roots-suction. In the present research program, a comprehensive experimental study regarding the deformation characteristics of a sandy loam soil from Ottawa due to tree-root-suction is undertaken, using specially designed equipment. The study has been undertaken using a sandy loam soil so that the testing program can be conducted in a shorter period of time. An artificial rooting system (ARS) was designed and placed in a specially designed tank at the University of Ottawa to simulate tree-roots-suction and measure soil surface settlements associated with a decrease in natural water content (or increase in soil suction) using particle image velocimetry (PIV) technique. The ARS consists of an artificial root, suction generator, matric suction and volumetric water content monitoring devices. The variation of matric suction and volumetric water content are monitored at various depths using the instrumentation of the ARS. Based on the results of the experimental studies, a methodology is proposed to model the settlement behaviour of sandy loam soils due to suction from ARS, using commercial finite element software, SEEP/W and SIGMA/W (i.e. software package of GeoStudio 2007). The study offers a reasonably good comparison between the measured surface settlements and those estimated using the finite element modelling analysis. The modelling methodology presented in this thesis is promising and may be extended for estimating the settlement behaviour associated with the tree roots suction of Leda clay deposits and to other soils.

Shallow foundations rested on Leda clay that are widely distributed in Eastern Canada exhibit shrinkage characteristics and are prone to differential settlements. Due to this reason, significant repairs are necessary to the foundations and basements of residential structures constructed in Leda clay deposits. Differential settlements are commonly attributed to the changes in the natural water content of soils associated with water infiltration, evaporation or plant transpiration (i.e., tree-roots-suction). Various research studies have been undertaken to estimate the possible settlements of shallow foundations associated with the water infiltration or evaporation. Several thumb rules have been proposed through research studies, providing recommendations with respect to the distance at which trees must be planted as a function of their heights at maturity such that differential settlements can be avoided. However, limited studies have been carried out to estimate or model the settlements of shallow foundations taking into account the influence of tree-roots-suction. In the present research program, a comprehensive experimental study regarding the deformation characteristics of a sandy loam soil from Ottawa due to tree-root-suction is undertaken, using specially designed equipment. The study has been undertaken using a sandy loam soil so that the testing program can be conducted in a shorter period of time. An artificial rooting system (ARS) was designed and placed in a specially designed tank at the University of Ottawa to simulate tree-roots-suction and measure soil surface settlements associated with a decrease in natural water content (or increase in soil suction) using particle image velocimetry (PIV) technique. The ARS consists of an artificial root, suction generator, matric suction and volumetric water content monitoring devices. The variation of matric suction and volumetric water content are monitored at various depths using the instrumentation of the ARS. Based on the results of the experimental studies, a methodology is proposed to model the settlement behaviour of sandy loam soils due to suction from ARS, using commercial finite element software, SEEP/W and SIGMA/W (i.e. software package of GeoStudio 2007). The study offers a reasonably good comparison between the measured surface settlements and those estimated using the finite element modelling analysis. The modelling methodology presented in this thesis is promising and may be extended for estimating the settlement behaviour associated with the tree roots suction of Leda clay deposits and to other soils.

No description available.

Urban runoff continues to impair water quality and there is an increasing need for stormwater management within the limited confines of urban spaces. We propose a system of structural soil and trees that can be incorporated beneath pavement. Structural soil has a high load-bearing capacity yet is engineered to support tree root growth. Stormwater is directed into a structural soil reservoir below the pavement where tree roots can also thrive. Two container experiments evaluated tree function in this system. We examined whether tree roots can grow into compacted subsoils and if root penetration increases soil infiltration rate. Quercus velutina, Acer rubrum, and a no-tree variant were planted in 26.5 L (7 gal) containers and the rootballs surrounded by compacted clay loam. Roots grew into all layers of the compacted soil. Infiltration rate increased by 63% (+/-2%) compared to no-tree containers. A second experiment evaluated water uptake and tree development in fluctuating water tables. Quercus bicolor and Fraxinus pennsylvanica were planted in 94.6 L (25 gal) containers with structural soils (either Stalite or CU® Structural Soil). Trees were subjected to fluctuating water tables simulating infiltration rates of 2, 1, and 0.1 cm/hr for two growing seasons. Trees thrived in all infiltration regimes but roots were shallower in slowly drained treatments. Trees grew best and transpired the highest water volume with moderate infiltration. Even if trees uptake only small volumes of water, increased canopy size compared to conventional plantings (because of greater penetrable soil volume) allows greater rainfall interception thus decreasing runoff. / Master of Science

No description available.

In urban areas, trees are often planted in bare soil sidewalk openings (tree pits) which recently are being covered with permeable pavements. Pavements are known to alter soil moisture and temperature, and may have implications for tree growth, root development and depth, drought resilience, and sidewalk lifting. Furthermore, tree pits are often the only unsealed soil surface and are important for water exchange between soil and atmosphere. Therefore, covering tree pits with pavement, even permeable, may have implications for the urban water balance and stormwater management. A better understanding of permeable pavement on tree pavement soil system functioning can inform improved tree pit and street design for greater sustainability of urban environments. We conducted experiments at two sites in Virginia, USA (Mountains and Coastal Plain) with different climate and soil. At each location, we constructed 24 tree pits in a completely randomized experiment with two factors: paved with resin-bound porous-permeable pavement versus unpaved, and planted with Platanus x acerifolia 'Bloodgood' versus unplanted (n = 6). We measured tree stem diameter, root growth and depth, and soil water content and temperature over two growing seasons. We also monitored tree sap flow one week in June 2017 at the Mountains. In addition, we calibrated and validated a soil water flow model, HYDRUS-1D, to predict soil water distribution for different rooting depths, soil textures and pavement thicknesses. Trees in paved tree pits grew larger, with stem diameters 29% (Mountains) and 51% (Coastal Plain) greater. Roots developed faster under pavement, possibly due to the increased soil water content and the extended root growing season (14 more days). Tree transpiration was 33% of unpaved and planted pit water outputs, while it was 64% for paved and planted pits. In June 2016, planted pits had decreased root-zone water storage, while unplanted pits showed increased storage. A water balance of the entire experimental site showed overall decreased soil water storage due to tree water extraction becoming the dominant factor. HYDRUS-1D provided overall best results for model validation at 10 cm depth from soil surface (NSE = 0.447 for planted and paved tree pits), compared to 30- and 60 cm depths. HYDRUS-1D simulations with greater pavement thickness resulted in changes in predicted soil water content at the Coastal Plain, with higher values at 10- and 30-cm depths, but lower values at 60-cm depth. At the Mountains, virtually no difference was observed, possibly due to different soil texture (sandy vs clayey). Tree pits with permeable pavement accelerated tree establishment, but promoted shallower roots, possibly increasing root-pavement conflicts and tree drought susceptibility. Paved tree pits resulted in larger trees, increasing tree transpiration, but reduced soil evaporation compared to unpaved pits. Larger bare soil pits surrounded by permeable pavement might yield the best results to improve urban stormwater retention. Also, HYDRUS 1D was successful at simulating soil water content at 10-cm depth and may be valuable to inform streetscape design and planning. / PHD / Trees in cities are often planted in pavement cutouts (tree pits) that are usually the only available area for water exchange between soil and atmosphere. Tree pits are typically covered with a variety of materials, including permeable pavement. Pavements are known to modify soil water distribution and temperature, affecting tree growth, rooting depth, drought resilience, and sidewalk lifting. A better understanding of this system can inform tree pit and street design for greater sustainability. We constructed 24 tree pits at each of two regions in Virginia, USA (Mountains and Coastal Plain). These tree pits were paved with permeable pavement or unpaved, and planted with London Plane or unplanted. We measured stem diameter, root growth, and soil water content and temperature over two years and tree sap flow for one week in summer (Mountains only). We also used a soil water flow model, HYDRUS-1D, to predict water distribution for different rooting depths, soil textures and pavement thicknesses. After the first growing season trees in pavement were larger, with stem diameters 29% (Mountains) and 51% (Coastal Plain) greater. Roots developed faster under pavement, possibly due to increased soil water content and a 14-day increase in root growing season. Also, in June 2017, tree transpiration was 33% of unpaved-and-planted pit water outputs, and 64% of paved-and-planted pits. In June 2016, root-zone water storage decreased in planted pits but increased in unplanted pits. When considering the entire experimental site, soil water storage decreased, with tree water extraction being the dominant factor. HYDRUS-1D performed better at 10-cm soil depth than at 30- and 60-cm depths. At the Coastal Plain, HYDRUS-1D predicted higher soil water content at 10- and 30-cm depths with increased pavement thickness, but lower values at 60-cm depth. At the Mountains, there was no effect, possibly due to higher clay content. Permeable pavement accelerated tree establishment, but promoted shallower roots, increasing drought susceptibility and risk for root-pavement conflicts. Pavement resulted in larger trees and greater transpiration, but reduced soil evaporation. Larger bare-soil pits surrounded by permeable pavement might optimize stormwater retention.

Indiana University-Purdue University Indianapolis (IUPUI) / Underground septic systems thrive or fail based on the relationship with their local environment. This paper explores ways environmental variables such as soil type, tree roots, degree of slope, and impervious surfaces affect on-site wastewater treatment systems. It also discusses the effects each of these variables may have on a septic system, and the resulting impact a compromised system may have on the surrounding environment. This research focuses on an approximately 20 square mile area of central Washington Township in Marion County, Indiana. This area of central Indiana contains a large septic system owning population in a sampling of different environments such as wooded areas, hilly areas, and a variety of different soil types.