Measuring tilt of tree structural root zones under static and wind loading

Abstract This paper describes a non-destructive method to measure the tilt angle ( Φ ) of a tree's structural root zone as it tilts under winds or static pulling. This method records both magnitude and direction of the dynamic tilt response of the tree root plate. A tri-axial accelerometer is used as a tilt sensor and is attached to the base of the tree trunk at ground level. Dynamic root plate tilt can be measured using 20 Hz sampling. The tilt sensor was calibrated in a laboratory then used in field tests on trees that were statically loaded, then on trees subject to natural wind conditions. The maximum structural root zone tilt recorded during static pulling tests was 0.60°. Under natural wind conditions the maximum root plate tilt recorded was 0.88°. Some practical limitations of the sensor in the field due to the battery capacity and reliability are discussed.

[1]  T. Fourcaud,et al.  A finite element model for investigating effects of aerial architecture on tree oscillations. , 2006, Tree physiology.

[2]  Barry Gardiner,et al.  A prism-based system for monitoring the swaying of trees under wind loading , 1998 .

[3]  K. Rennolls,et al.  A Root Anchorage Model for Shallowly Rooted Sitka spruce , 1990 .

[4]  M. P. Coutts,et al.  Components of tree stability in Sitka Spruce on peaty gley soil , 1986 .

[5]  C. Baker,et al.  Measurements of the natural frequencies of trees , 1997 .

[6]  A. Stokes.  Strain distribution during anchorage failure of Pinus pinaster Ait. at different ages and tree growth response to wind-induced root movement , 2000 .

[7]  M. F. O'sullivan,et al.  Tree Stability in Relation to Cyclic Loading , 1993 .

[8]  M. P. Coutts,et al.  Root architecture and tree stability , 1983, Plant and Soil.

[9]  Thomas K. Flesch,et al.  Wind and remnant tree sway in forest cutblocks. II. Relating measured tree sway to wind statistics , 1999 .

[10]  H. Peltola,et al.  Mechanical stability of Scots pine, Norway spruce and birch: an analysis of tree-pulling experiments in Finland , 2000 .

[11]  H. Mayer,et al.  Vibration behavior of plantation-grown Scots pine trees in response to wind excitation , 2010 .

[12]  John R. Moore.  Differences in maximum resistive bending moments of Pinus radiata trees grown on a range of soil types. , 2000 .

[13]  J. Petty,et al.  An Assessment of the Static and Dynamic Factors Involved in Windthrow , 1988 .

[14]  Andrew Dawson,et al.  Experimental observations of the aerodynamic characteristics of urban trees , 1994 .

[15]  B. Gardiner,et al.  Wind and Trees: The interactions of wind and tree movement in forest canopies , 1995 .

[16]  M. Rodgers,et al.  Wind and Trees: An experimental investigation of the effects of dynamic loading on coniferous trees planted on wet mineral soils , 1995 .

[17]  J. Grabosky,et al.  Effects of Pruning Dose and Type on Trunk Movement in Tropical Storm Winds , 2008, Arboriculture & Urban Forestry.

[18]  S. A. Neild,et al.  Estimating stem and root-anchorage flexibility in trees. , 1999, Tree physiology.

[19]  Kenneth R. James,et al.  Precision digital instruments to measure dynamic wind loads on trees during storms , 2008 .

[20]  Alexis Achim,et al.  Wind loading of trees: influence of tree size and competition , 2010, European Journal of Forest Research.

[21]  H. Peltola,et al.  Mechanical stability of trees under static loads. , 2006, American journal of botany.

[22]  R. Milne,et al.  Dynamics of swaying of Picea sitchensis. , 1991, Tree physiology.

[23]  Walter Ammann,et al.  Anchorage of mature conifers: resistive turning moment, root-soil plate geometry and root growth orientation. , 2007, Tree physiology.

[24]  B. Gardiner,et al.  Anchorage of coniferous trees in relation to species, soil type, and rooting depth , 2006 .

[25]  N. Haritos,et al.  Mechanical stability of trees under dynamic loads. , 2006, American journal of botany.

[26]  H. Peltola.  Swaying of trees in response to wind and thinning in a stand of Scots pine , 1996 .

[27]  Uldis Silins,et al.  Measure of simultaneous tree sways and estimation of crown interactions among a group of trees , 2001, Trees.

[28]  Duncan Ray,et al.  The effect of soil water-table depth on root-plate development and stability of Sitka spruce , 1998 .

[29]  Barry Gardiner,et al.  A mathematical model to describe the dynamic response of a spruce tree to the wind , 1998, Trees.

[30]  Χρήστος Κ. Φράγκος.  Proceedings of the 2nd international conference , 2014 .

[31]  B. Gardiner,et al.  An inexpensive instrument to measure the dynamic response of standing trees to wind loading , 2005 .

[32]  W. Ammann,et al.  Root-soil rotation stiffness of Norway spruce (Picea abies (L.) Karst) growing on subalpine forested slopes , 2006, Plant and Soil.

[33]  M. Kalberer,et al.  The root–soil system of Norway spruce subjected to turning moment: resistance as a function of rotation , 2007, Plant and Soil.

[34]  Thierry Fourcaud,et al.  A numerical model of tree aerodynamic response to a turbulent airflow , 2008 .