Tree health

Trees can live for a long time but eventually die, either from natural causes or killed by man. Ill-health of trees can be diagnosed, and early treatment, pruning or felling to prevent the spread may result in timber stocks and amenity trees being saved. Arborists/arboriculturists need to be aware of the risk posed by hazardous trees. Construction projects sometimes avoidably damage trees. Trees can live for a long time but eventually die, either from natural causes or killed by man. Ill-health of trees can be diagnosed, and early treatment, pruning or felling to prevent the spread may result in timber stocks and amenity trees being saved. Arborists/arboriculturists need to be aware of the risk posed by hazardous trees. Construction projects sometimes avoidably damage trees. The causes of tree damage and abnormalities can conveniently be divided into either biotic (from living sources) or abiotic (from non-living sources). Biotic sources include insects (e.g. that bore into the tree), mammals (e.g. deer that rub bark off), fungi, birds, nematodes, bacteria and viroids. Abiotic sources include lightning, vehicles impacts, construction activities, drought, waterlogging, frost, winds, chemicals in the soil and air and soil nutrient deficiencies. Construction activities can involve any of a number of damage types, including grade changes or compaction that prevent aeration to roots, spills involving toxic chemicals such as cement or petroleum products, or severing of branches or roots. Trees with thinner bark such as birch and American sycamore are more sensitive to such damage.