FOLIAR SENESCENCE IN AN ASPEN (POPULUS-TREMULOIDES) CLONE - THE RESPONSE OF ELEMENT RESORPTION TO INTERRAMET VARIATION AND TIMING OF ABSCISSION

Nutrient movements in the senescing foliage of a Rhode Island aspen were measured. Mean resorption of N, P, and Cu was 43, 51 and 10%, respectively. Aluminium, B, Ca, Fe, Mg, Mn, and Zn increased or remained unchanged in senescing foliage during 1986. Resorption of N and P decreased, respectively, from 56 and 64% in 1986 to 24 and 38% in 1988. Resorption of N and P decreased, respectively, from 56 and 64% in 1986 to 24 and 38% in 1988. Older, larger ramets resorbed less N and Cu. Timing of abscission strongly influenced resorption and may have been related to drought conditions in 1988 and to differential exposure to wind in all years. Resorption of N, P and Cu was lowest in those ramets that lost their leaves earliest and in leaves that senesced earliest on individual ramets. -from Authors