Storm Induced Tree Failures From Heavy Tree Weights and Weather Loads

Summary: Geoff Kempter of Asplundh Tree Expert Company links storm induced tree failures to tree weights and weather loads in cyclones, ice storms and thunderstorms.

Storms affect trees, which concern arborists; some areas are more prone to thunderstorms than others; Annual Average Severe Thunderstorm Watches per Year (20-Year Average, 1993-2012): NOAA (National Oceanic and Atmospheric Administration) National Weather Service Storm Prediction Center (SPC), Public Domain, via NOAA SPC

Storm induced tree failures acknowledge tree weights and weather loads, according to Storm Response, Part 1: Types of Storms and Their Effects on Trees in the June 2013 issue of Arborist News.

Defectiveness, failure or strength becomes the top responses of trees to icy, rainy, snowy or windy storms, according to Geoff Kempter of Asplundh Tree Expert Company. Trees carry the load of animals, equipment, people, structures and weather-related residue and of their own weight in branches, flowers, fruits, leaves, nuts, trunks and twigs. Gravity and sunlight do what the energy source and the physical force respectively do best by drawing above-ground tree loads downward and above-ground tree parts upward.

Roots enable trees to endure excess loads, exterior forces, extra stress and extreme weather until below-ground food webs experience serious damage, soil disturbances and structural defects.

Storms alone or combined with structural "defects, such as leans, decay, girdling roots, or poor branch attachments," furnish the breaking stress behind storm induced tree failures.

Clayey soils get saturated and waterlogged by prolonged downpours and floods and generate insufficient "friction between roots and soil" to sustain the "holding capacity of roots." Wind intensities sustained at 64 to 82 knots (74 to 95 miles, 119 to 153 kilometers per hour) hinder root-anchoring and trunk-stabilizing capacities of some trees. Wind intensities from 83 to 112 knots (96 to 129 miles, 154 to 208 kilometers per hour) inflict sufficient damage to snap and topple many trees.

Wind intensities of 113 to 136 knots (130 to 156 miles, 209 to 251 kilometers per hour) and up jar, snap and uproot most area trees.

Tree strength keeps up with expected, normal, prevailing, typical, usual occurrences of ice, rain, snow and wind in the absence of stressed soils and structural defects.

"[H]eavy downpours on dense foliage," stubborn ice on branches and twigs, and wet snow on leafed-out trees let even strong trees become storm induced tree failures. Storms, whether atypical or prevalent in an area, may "come in many forms, and the damage to trees varies depending on storm type, location, and intensity." Governments notify an area's population that "conditions are favorable for storms" through watches and that storms are "imminent or occurring" through warnings to take "immediate" action.

The Rocky Mountain chinook, the Nor'easter, and the Santa Ana of California and Mexico offer examples of "high-wind phenomena" monitored seasonally in specific North American locales.

Cyclones and hurricanes, ice storms and thunderstorms respectively provide regional, seasonal high-wind examples of Atlantic and Pacific coastal, snow-prone, and central and Gulf coastal North America.

Circulating, low atmospheric pressure, rainy, widespread, windy systems over summer transitioning into autumn's warm waters qualify as counterclockwise-rotating northerly hurricanes and typhoons and clockwise-rotating southerly cyclones. Central and Gulf coastal North America's rising unstable thunderstorms reach hourly 100-plus-mile (161-plus-kilometer) speeds over 240-plus-mile (386-plus-kilometer) distances as derechos and 200-plus-mile (322-plus-kilometer) speeds in tornados. Ice storms shower warm-aired rain down to autumn's and spring's below-freezing landscapes as wet snow, "lower than a 10:1 snow-to-water" equivalent, that snap leafed-out weighted-down trees.

Storm induced tree failures turn private and public spaces into obstacle courses whose dangers trend less ominously when tree specialists treat site stresses and structural defects.

Arborists in North America contend with damage inflicted upon trees by Atlantic and Pacific hurricanes; worldwide hurricane tracks, 1950-2005: NOAA, Public Domain, via NOAA SOS (Science on a Sphere)

Acknowledgment

My special thanks to:
talented artists and photographers/concerned organizations who make their fine images available on the internet;
University of Illinois at Urbana-Champaign for superior on-campus and on-line resources.

Image credits:

Storms affect trees, which concern arborists; some areas are more prone to thunderstorms than others; Annual Average Severe Thunderstorm Watches per Year (20-Year Average, 1993-2012): NOAA (National Oceanic and Atmospheric Administration) National Weather Service Storm Prediction Center (SPC), Public Domain, via NOAA SPC @ http://www.spc.noaa.gov/wcm/

Arborists in North America contend with damage inflicted upon trees by Atlantic and Pacific hurricanes; worldwide hurricane tracks, 1950-2005: NOAA, Public Domain, via NOAA SOS (Science on a Sphere) @ http://sos.noaa.gov/Datasets/dataset.php?id=539

For further information:

Gilman, Ed. 2011. An Illustrated Guide to Pruning. Third Edition. Boston MA: Cengage.

Hayes, Ed. 2001. Evaluating Tree Defects. Revised, Special Edition. Rochester MN: Safe Trees.

Kempter, Geoff. June 2013. "Storm Response, Part 1: Types of Storms and Their Effects on Trees." Arborist News 22(3): 12-19.
Available @ http://viewer.epaperflip.com/Viewer.aspx?docid=ddc3c70b-f119-40bf-a3da-a29d00e3748c#?page=12

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Available @ https://earth-and-space-news.blogspot.com/2013/04/urban-tree-root-management-concerns.html

Marriner, Derdriu. 16 February 2013. “Tree Friendly Beneficial Soil Microbes: Inoculations and Occurrences.” Earth and Space News. Saturday.
Available @ https://earth-and-space-news.blogspot.com/2013/02/tree-friendly-beneficial-soil-microbes.html

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Available @ https://earth-and-space-news.blogspot.com/2012/12/healthy-urban-tree-root-crown-balances.html

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Available @ https://earth-and-space-news.blogspot.com/2012/10/tree-adaptive-growth-tree-risk.html

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Available @ https://earth-and-space-news.blogspot.com/2011/04/benignly-ugly-tree-disorders-oak-galls.html

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