Population numbers count: Tools for near-term demographic analysis

Fox, GA Gurevitch, J

Ga. Fox et J. Gurevitch, Population numbers count: Tools for near-term demographic analysis, AM NATURAL, 156(3), 2000, pp. 242-256

31

INGLESE

Article

Environment/Ecology

AMERICAN NATURALIST

0003-0147 → ACNP

156

3

2000

242 - 256

ISI

0003-0147(200009)156:3<242:PNCTFN>2.0.ZU;2-#

How do unit or proportional changes in vital rates affect populations in th e short term? We present a new extension to standard methods of matrix mode l analysis that allows us to answer this question for the first time. By us ing the sensitivities of all the eigenvalues/vectors, rather than just the leading eigenvalue/vector pair, we can predict the consequences of unit or proportional changes in vital rates to population size and structure at any arbitrary time, not just when populations have neared their stable distrib ution. These extensions are particularly important in studying populations subject to frequent disturbance, where stable growth rare and stable distri bution do not provide sufficient information about the effects of changes i n the vital rates; managed populations in which short-term goals are define d; and the adequacy of the underlying matrix model for either short- or lon g-term understanding. We use analysis of empirical data on the cactus Coryp hantha robbinsorum to demonstrate this approach and show that short-term pr edictions can differ substantially from those based on standard, asymptotic , analysis.