Aspen Bibliography

Foliar senescence in an aspen (Populus tremuloides) clone: the response of element resorption to interramet variation and timing of abscission

Document Type

Article

Journal/Book Title/Conference

Canadian Journal of Forest Research

Volume

20

Issue

8

First Page

1156

Last Page

1164

Publication Date

1990

Abstract

Nutrient movements in the senescing foliage of a Rhode Island Populustremuloides Michx. clone were measured during the years 1986–1988. Mean resorption of nitrogen, phosphorus, and copper was 43, 51, and 10%, respectively. Aluminum, boron, calcium, iron, magnesium, manganese, and zinc increased or remained unchanged in senescing foliage during 1986. Resorption of nitrogen and phosphorus decreased, respectively, from 56 and 64% in 1986 to 24 and 38% in 1988. Mean resorption differed among the 20 ramets studied. Older, larger ramets resorbed less nitrogen and copper than younger, smaller ramets. 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 nitrogen, phosphorus, and copper was lowest in those ramets that lost their leaves earliest and in leaves that senesced earliest on individual ramets. Because P. tremuloides ramets had the physiological potential to resorb more nitrogen and phosphorus than they actually did in 1988, we introduced the terms potential resorption and realized resorption to differentiate between physiological potential and ecological reality. Our data suggest that at least some portion of realized resorption is determined stochastically by environmental constraints.

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