The Role of Water Stress in Tree Growth
Paul J. Kramer
Abstract: Urban trees often are subjected to soil and atmospheric stresses that reduce growth and vigor, increase susceptibility to insects and diseases, and cause premature death. Environmental stresses occasionally injure trees directly, as by freezing, but most injury is caused indirectly by inhibiting essential physiological processes. Water stress is particularly important because it is so frequent and affects so many processes. The injury caused by water stress can be reduced through prevention of stress by irrigation, postponement by development of extensive root systems and control of transpiration, and by selection of trees with a high tolerance of dehydration. More attention should be given to selection of species and individuals with high tolerance of the more destructive stresses such as water deficit, air pollution, and unfavorable soil conditions. This will require the cooperative efforts of arborists, physiologists, and tree breeders.