Growth rates seasonal differences

The total concentration of sugars in sap varies due to several factors. Variation between individual trees may be quite large due to differences in genetics, growth rate, and crown density. However, the ranking of any one tree relative to its neighbors tends to remain relatively constant both within a season and from season to season (Taylor, 1956). 

A complete investigation of the environmental influences on the growth rate is still to be made. In particular, it has been emphasized that there is an interaction between nitrogen and phosphorus limitations as well as other effects which influence the phytoplankton growth rate. Also, these effects are different for differing species. The species-dependent effects are important in the problem of the seasonal succession of phytoplankton species. 

The close relationships of larval growth rates and efficiencies (see Fig. 7.1 Waldbauer, 1968) with leaf nitrogen content is illustrated in Fig. 7.2. The symbols represent the mean performance ( SE) of the black swallowtail butterfly, Papiliopolyxenes, larvae for 11 different species of the Umbelliferae family at particular times of the growing season. The poor correspondence of plant N... 

Fig. 7.19 The larval developmental time (days) of various populations of Callosamia promethea on different plants, presented as a function of leaf water and leaf nitrogen contents. Seasonal changes in leaf chemical composition during the rearing periods are encompassed by enclosure lines for each species. Differential survival and growth rates were observed for an initial 12 000 larvae of different C. promethea populations (Scriber, 1983). However, in this figure the mean duration for larvae on each plant is presented regardless of geographic source.

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