Trees

Aging tree infrastructure

All trees have a finite life expectanc ranging from a few years to decades, centuries or even a millennia. However these figures are often misleading since they count for trees growing under "ideal" conditions in their natural environments.

Trees are affected by a wide variety of abiotic (non biological) and biotic (biological) causes.

Abiotic can be human caused or natural.

Examples of the 'human factor' are habitat destruction, pollution and poor cultural practices like planting too deeply, poor quality stock, lack of aftercare and not providing enough space for the roots, which creates unfavourable conditions for trees.

Natural abiotic factors that can damage tree health include mineral deficiencies in the soil as well as climatic stresses such as extreme temperature or moisture conditions, doughts and flooding.

Biotic factors are often the more easily observed causal agents of tree decline. These include fungi, viruses, bacteria, nematodes (parasitic worms), wood and bark borer and insect defoliators such as willow saw fly.

Trees in the urban landscape are stressed in many ways that compromise their vigor and vitality and make them more susceptable to disease.