Abstract

Transplanting large-caliper trees frequently leads to poor tree growth and survival. A longitudinal study of the changes in water relations and canopy development was conducted to study this effect. Pruning and watering were used to test the recovery of maple trees following transplanting. Water potential (ψ), transpiration rate (t_r), and leaf area index (LAI) were the measured dependent variables. In the summer after transplanting, date and treatment significantly affected LAI, tr and mid-day ψ in Acer truncatum. In this species, trees receiving a post-transplant pruning treatment in combination with watering did not significantly differ in tr and mid-day ψ from nontransplanted controls, although LAI did differ between these treatments. In both A. truncatum and A. tataricum ginnala, treatment and day interacted significantly on pre-dawn ψ. While the seasonal patterns differed between species, the most negative pre-dawn ψ measurements were made four months after transplanting. In the spring following transplanting, significant differences due to prior-year treatment were again measurable in mid-day ψ in leaves of A.tataricum ginnala. In that species, mid-day ψ of the transplanted control trees differed from non-transplanted controls. Transplanting led to a measurable, long-term water stress. Pruning and watering in combination partially relieved that stress. Leaf area index was markedly affected by transplanting. It is suggested that this readily-measurable variable could be useful in assessing recovery from transplant stress.