Seasonal photosynthate allocation of the Californian coast live oak Quercus agrifolia

Abstract

The growth and competitive success of a plant species involves the integrated use of a number of resources which are in limited supply, including carbon, water, and nutrients. While many studies have reported rates of carbon uptake in photosynthesis, only rarely have they simultaneously described subsequent carbon allocation processes. The timing of carbon allocation to and the forms and amount of carbon allocated to different functions such as growth, storage, maintenance and protection are important to fitness (Mooney 1972). Studies of two evergreen shrub species, Heteromeles arbutifolia (Mooney and Chu 1974) and Larrea divaricata (Oechel et al. 1972), have provided basic descriptions of the seasonal changes in partitioning of photosynthate in shrubs from semiarid and arid regions. Because assimilate partitioning is strongly influenced by both plant size and sink distribution, allocation patterns of trees may differ considerably from shrubs. Since trees have higher maintenance demands than shrubs, this too may lead to important difference in their allocation patterns for photosynthate (McLaughlin et al. 1979).