The problem of finding available reviewers for ecological journals
during the field season, that Sarah Goslee reported, is similar to
the problem that NSF has in finding ad hoc reviewers for grant proposals.
I've heard from several NSF program managers over the years that
there are ecologists (some very senior) who are funded (sometimes
very well) by NSF but who will not review proposals or serve on
panels when asked. I don't know whether that has ever affected
funding decisions, but I have also heard that when program managers
are told at the last minute that additional funds have become
available and need to be spent right away (e.g., just before the end
of the fiscal year), the fact that a particular PI has been a good
citizen and helped with ad hoc reviews and panels can influence a
decision about what proposals to de-decline. So it is possible to
parasitize the funding system (i.e., benefit from it but not
contribute to it), and to benefit from your contributions to the process.
If you haven't served on an NSF panel, you would probably find it
interesting and instructive, both in terms of giving you insights
into how the funding process works (very fairly, in my experience)
and what kind of proposals are well received by reviewers and panel
members. An individual panel member who feels strongly about the
merit of a particular proposal can often have a significant effect on
how it is rated by a panel, if her/his arguments are persuasive.
David Inouye