A demographic approach to understanding the effects of climate on population growth

Abstract

Amphibian life history traits are affected by temperature and precipitation. Yet, connecting these relationships to population growth, especially for multiple populations within a species, is lacking and precludes our understanding of how amphibians are distributed. Therefore, we constructed Integral Projection Models (IPM) for five populations along an elevational gradient to determine how climate and season affects population growth of a terrestrial salamander Plethodon montanus and the importance of demographic vital rates to population growth under varying climate scenarios. We found that population growth was typically higher at the highest elevation compared to the lower elevations whereas varying inactive season conditions, represented by the late fall, winter and early spring, produced a greater variation in population growth than varying active season conditions (late spring, summer, and early fall). Furthermore, survival and growth was consistently more important, as measured by elasticity, compared to fecundity and large females had the greatest elasticity compared to all other sizes. Our results suggest that changing inactive season conditions, especially those that would affect the survival of large individuals, may have the greatest impact on population growth. Therefore, we recommend experimental studies focused on the inactive season to determine the mechanism by which these conditions can affect survival.