Life-history variation mediates the importance of population structure to the short-term dynamics of plant populations worldwide

James Inman Cant , Christina Maria Hernandez, David Koons, David J Hodgson, Man Qi, Andrew Hector, Iain Stott, Rob Salguero-Gomez

A population’s structure (i.e., the distribution of individuals across the life cycle of a species) influences how it responds to environmental changes and recurrent disturbances, and shapes its vulnerability to extinction. Yet, despite compelling evidence that population structures are rarely stationary over time, assessments of population viability have only recently begun to consider how a population’s structure interacts with its vital rates of survival, development, and fecundity to determine its demographic performance. Using 268 comparisons of population dynamics in 56 plant species across differing time periods, locations, and/or experimental treatments, we use transient Life Table Response Experiments (tLTREs) to quantify how changes in population structure and vital rates contribute to observed variation in demographic performance. We illustrate how changes in population structure are major contributors to short-term (i.e. transient) demographic performance, and are just as important as the effects of, more routinely evaluated, changes in survival and fecundity rates for informing population viability assessments. Moreover, these contribution patterns challenge prevailing understanding of the links between plant growth form and population viability. Accordingly, we emphasise how quantifying the effects of population structure on transient population dynamics can reveal key mechanistic insights necessary for accurately predicting the responses of natural populations worldwide to ongoing global change. Indeed, linking the structure and dynamics of natural populations is essential for the effective management and conservation of global biodiversity.