If λ = 1, the population is:
For a population observed at discrete time intervals, the finite rate of increase is λ = N(t+1)/N(t). A value of 1 means that each census contains the same number of individuals as the preceding census, so abundance is stable rather than rising or falling. Equivalently, births plus immigration exactly balance deaths plus emigration over the interval. This does not imply that no individuals are born or die; demographic turnover may be substantial while net population change remains zero. In an age-structured population, λ = 1 is the long-term result after the stable age distribution has been re
Ref: Ecology: Concepts and Applications, Molles, 9th Ed., Ch. 11