In Chapter 3 we discussed how individuals within populations will vary with respect to their age, size and stage of development and presented survivorship curves as one way to display age-structured data. For example, we showed the age structure of spotted knapweed (C. maculosa) in Fig. 3.7, the survivorship curve of Drummond's phlox (P. drum-mondii) in Fig. 3.9, and the general idealized survivorship curves in Fig. 3.10. In this section we discuss how to collect survival data and construct survivorship tables and curves.

There are two ways to collect survivorship data:

• by looking at the age structure of a population at one point in time ('static life table');

Point a

Point a

Point b

i ii

Point b

* Species A, sugar maple

0 Species B, red oak

Species C, Norway maple

0 0

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