Storm Impacts

Storm events can cause considerable damage to trees. Below are some of the impacts caused by hurricanes, tornados, or storm events.

Wind

Wind is often the first sign of a hurricane approaching. Leaves and branches may be stripped off and entire trees may be twisted, broken or uprooted altogether. Some trees are more susceptible to wind damage than others. Trees with healthy root systems have better chances of survival. However, if remaining trees survive one storm, and another hurricane encompasses the same area in a short period of time, those remaining trees are considered stressed and may not make it through subsequent storms. Hurricanes can also produce tornadoes with winds measuring more than 200 mph. Trees may be completely debarked by small, flying debris or downed altogether. In either case, these trees will need to be removed.

Lightning

Hurricanes also are typically accompanied by thunderstorms and lightning. Because of their height, trees are a prime target for lightning. However, damage caused by lightning varies greatly. The damage may be minimal if the electricity is conducted along the outside of the tree. In this case, blown off bark and scarring will be apparent. The damage may extend to a more serious condition known as trunk shatter. In this event, lightning charge penetrates into the tree's trunk, turning moisture into steam and causing the tree to explode. The most commonly struck trees are oaks, elms, poplars and pines. These trees typically are found in most yards.

Flooding

After hurricanes strike, many low-lying communities are impacted by short-term flooding. Flooding has been known to damage trees by loosening and/or removing the soil that supports root systems. In areas that have been flooded for extended periods of time, trees can suffer from the accumulation of organic toxins in the soil and the reduced flow of oxygen to the roots. Various characteristics of a tree, including height, age and species, along with environmental factors like season, temperature and flood water duration, affect a tree's flood tolerance. The typical warning sign of flood damage in trees is curling and wilting of the leaves, followed by chlorosis (pale-colored leaves that have lost chlorophyll). Chlorosis is generally followed by leaf browning and ultimately, leaf loss.

Ice

Ice storms are caused by rain that supercools or freezes as it passes through below-freezing air. These ice coatings can grow to be several inches thick in various places. The weight of the ice, combined with any wind or outside forces, breaks the trees' branches. Normally, the taller and older a tree, the more susceptible it is to ice damage because older trees have larger crowns, more internal decay, and less limb and trunk flexibility. The severity of the ice damage depends on ice load and resistance of the trees determined by their physical characteristics - wood strength, elasticity and growth form, and on condition of the growing environment. In general, trees with brittle and weak wood, fine branches, and greater canopy surface, such as pine trees which retain their needles, are more likely to suffer ice damage. Some trees that have a high ice storm survival rates include: yellow birch, American hornbeam, beech and oak.