Matrix Projection Models Research Articles

Decomposition of official population projections in Brazil

Brazil’s population has continually changed over time. However, the effects of each demographic component on official population projections are still unclear. In this research, we replicate the Population Projections Revision 2018 of the Brazilian Institute of Geography and Statistics using a projection matrix model and the cohort-component method by sex, age and geographic regions. Thereafter, we established four alternative scenarios to decompose the official benchmark scenario into four demographic effects (fertility, age structure, mortality, and migration) and one residual effect. The results reveal that fertility and age structure effects have been the main drivers of the population dynamics between 2010 and 2060. On the one hand, the negative effect of fertility below replacement level has been mostly offset by the still positive effect of the age structure, even across regions in the country. On the other hand, age structure effect has been decreasing over time. By 2048, the effects of age structure, mortality and migration will no longer counterbalance fertility effects, resulting in a population decline.

Youth Experiencing Parental Death Due to Drug Poisoning and Firearm Violence in the US, 1999-2020

Youth (those aged <18 years) parental death has been associated with negative health outcomes. Understanding the burden of parental death due to drug poisoning (herein, drugs) and firearms is essential for informing interventions. To estimate the incidence of youth parental death due to drugs, firearms, and all other causes. This cross-sectional observational study was conducted using vital registration, including all US decedents, and census data from January 1990 through December 2020. Data were analyzed from May 30, 2023, to March 28, 2024. Parental death due to drug poisoning or firearms. A demographic matrix projection model was used to estimate the number and incidence of youth experiencing parental death, defined as the death of 1 or more parents, per 1000 population aged less than 18 years. Analyses evaluated parental deaths by drugs, firearms, and all other causes from 1999 through 2020 by race and ethnicity. Between 1999 and 2020, there were 931 785 drug poisoning deaths and 736 779 firearm-related deaths with a mean (SD) age of 42.6 (16.3) years. Most deaths occurred among males (73.8%) and White decedents (70.8%) followed by Black (17.5%) and Hispanic (9.5%) decedents. An estimated 759 000 (95% CI, 722 000-800 000) youth experienced parental death due to drugs and an estimated 434 000 (95% CI, 409 000-460 000) youth experienced parental death due to firearms, accounting for 17% of all parental deaths. From 1999 to 2020, the estimated number of youth who experienced parental death increased 345% (95% CI, 334%-361%) due to drugs and 39% (95% CI, 37%-41%) due to firearms compared with 24% (95% CI, 23%-25%) due to all other causes. Black youth experienced a disproportionate burden of parental deaths, based primarily on firearm deaths among fathers. In 2020, drugs and firearms accounted for 23% of all parental deaths, double the proportion in 1999 (12%). Results of this modeling study suggest that US youth are at high and increasing risk of experiencing parental death by drugs or firearms. Efforts to stem this problem should prioritize averting drug overdoses and firearm violence, especially among structurally marginalized groups.

Genetic predictors of population resilience: A case study of native Brook Trout in headwater streams

AbstractObjectivePopulations of eastern Brook Trout Salvelinus fontinalis face threats from several sources, such as habitat fragmentation, climate change, and competition with introduced salmonids. As a native species, understanding how these populations will respond to disturbances is paramount to their management and effective conservation. A population's ability to respond to disturbance, its resilience, is influenced by several factors. One such group of factors is population genetics.MethodsWe calculated population resilience metrics based on transient dynamics using population projection matrix models. Long‐term demographic data from 23 headwater stream Brook Trout populations were used to parameterize models. Genetic data were collected, and genetic indices were calculated. Partial redundancy analysis was then used to evaluate relationships between resilience metrics and genetic indices.ResultInbreeding coefficient, rarefied allelic richness, pairwise genetic differentiation (FST), and effective population size were all found to be important variables in predicting resilience.ConclusionOur results suggest that genetic isolation may increase the demographic resilience in Brook Trout through faster generation times and higher juvenile survival, but this likely comes at the cost of increased extinction risk and truncated size structures. Genetic indices can provide insight into gene flow between populations, thus the relationship between population connectivity and resilience. Given the importance of connectivity to population resilience, restoring and maintaining movement corridors could affect resilience in headwater Brook Trout populations.

Life history costs drive the evolution of mycoheterotrophs: Increased sprouting and flowering in a strongly mycoheterotrophic Pyrola species

Abstract Land plants are typically photosynthetic, but some species have lost the ability to photosynthesize, instead relying on mycorrhizal fungi to obtain carbon. Increasing levels of partial mycoheterotrophy, in which seemingly autotrophic plants receive fungal carbon from their fungal partners, and reduced sprouting in concert with greater reproduction when sprouting, may be intermediate steps in the evolution of this trait. We studied the microevolutionary demography of Pyrola japonica and the closely related species P. subaphylla, which are currently considered sister species. While these species are both partially mycoheterotrophic, P. subaphylla is more strongly so, indicating that it may be closer to evolving full mycoheterotrophy. We tracked individuals in two nearby populations in Fukushima, Japan from 2015 to 2020. We analysed vital rates, population trends and long‐run population structure with historical function‐based matrix projection models. We assessed how shifts in P. subaphylla demography relate to fitness using a stochastic life table response experiment (SLTRE). P. subaphylla exhibited strong costs of growth to survival and of reproduction to sprouting, size and fecundity. It sprouted more than P. japonica but to smaller stages. P. subaphylla's flowering frequency was approximately four times that of P. japonica, but after flowering it was smaller and more likely to die. These life history costs appeared to drive differences in fitness, measured as stochastic population growth rate. Relative to P. japonica, shifts in fitness in P. subaphylla were due more to shifts in means than standard deviations of matrix elements. Shifts in growth transitions had the strongest negative impacts on fitness but also had the strongest positive impacts. Increased shifts to small non‐flowering stages were associated with increased fitness, while transitions involving dormancy were associated more strongly with drops in fitness. Synthesis. As far as we are aware, we found the first evidence that costs of growth and reproduction drive the evolution of increased sprouting and smaller size as a species becomes more intensely mycoheterotrophic. Surprisingly, vegetative dormancy did not evolve with mycoheterotrophy. We suggest further studies assessing whether these seemingly maladaptive trends result from genetic drift, genetic linkage or another mechanism.

BatTool: projecting bat populations facing multiple stressors using a demographic model

Bats provide ecologically and agriculturally important ecosystem services but are currently experiencing population declines caused by multiple environmental stressors, including mortality from white-nose syndrome and wind energy development. Analyses of the current and future health and viability of these species may support conservation management decision making. Demographic modeling provides a quantitative tool for decision makers and conservation managers to make more informed decisions, but widespread adoption of these tools can be limited because of the complexity of the mathematical, statistical, and computational components involved in implementing these models. In this work, we provide an exposition of the BatTool R package, detailing the primary components of the matrix projection model, a publicly accessible graphical user interface (https://rconnect.usgs.gov/battool) facilitating user-defined scenario analyses, and its intended uses and limitations (Wiens et al., US Geol Surv Data Release 2022; Wiens et al., US Geol Surv Softw Release 2022). We present a case study involving wind energy permitting, weighing the effects of potential mortality caused by a hypothetical wind energy facility on the projected abundance of four imperiled bat species in the Midwestern United States.

Breeding Population Dynamics of Threatened Crawfish Frogs Inform Targets for Habitat Management

We used data from a five-year study at two focal breeding wetlands of a single Crawfish Frog (Rana areolata) population to demonstrate the relative importance and potential of tadpole survival as a target for population management. We concurrently estimated 11 vital rates in the field and used a females-only matrix projection model to estimate elasticities of demographic rates. We then simulated stochastic population dynamics at each wetland with and without immigration to estimate the intrinsic capacity for each focal breeding wetland to sustain a Crawfish Frog breeding population and the likelihood of breeding population persistence at each wetland. Elasticity of tadpole survival was second only to juvenile survival elasticity and 1.34–2.04 times greater than adult survival elasticity. Projections indicated that the Crawfish Frog population was not at risk of extinction but only one breeding site was capable of self-sustaining a breeding population. Because of low tadpole survival, the other breeding site was completely dependent on immigration to persist and was functioning as a population sink. Despite higher variability compared to terrestrial vital rates, larval survival did have a strong effect on population growth. Tadpole survival at the more productive breeding site was density dependent and likely related to wetland vegetation and predator and competitor abundance. Two additional findings were that annual survival of frogs following their first known breeding event was 48% lower compared to survival of frogs that had bred in two or more prior years, and adult temporary emigration from the breeding population was moderately high. Our study demonstrates the benefits of using population models that integrate density-dependent processes, temporary emigration from the breeding population, and state-specific adult survival, to identify larval habitats that function as population sinks and limit current population size and persistence probability. We contend that tadpole survival is an important and feasible habitat management target within broader conservation strategies for Crawfish Frogs and other amphibian species.

The cost of stabilising the German lapwing population: A bioeconomic study on lapwing population development and distribution using a cellular automaton

The populations of farmland birds such as the lapwing (Vanellus vanellus) are declining sharply. These populations suffer from frequent cultivation measures and degraded habitat quality on arable land. An effective conservation measure is the lapwing plot, an agriculturally unused section within an arable field. We address German lapwing population development and dispersal if different shares of the population are safeguarded by the use of lapwing plots. We adapted a matrix projection model and extended it by projecting population development in three different habitat types (arable land, grassland and optimal habitat) and in varying scenarios. We introduced a cellular automaton and developed a new algorithm to simulate dispersal dynamics. The results show that without further conservation measures, the population could decline from 70 000 breeding pairs in 2006 to 12 000 or 23 000 pairs in 2055, depending on the underlying assumptions. Our model can be used to set environmental goals and then simulate the necessary implementation levels of conservation measures, such as the lapwing plot, and estimate the corresponding costs. For the goal of at least stabilising the population, 60% of the pairs in the normal agricultural landscape need to be safeguarded. For the population on arable land the corresponding costs range between 1.6 and 2.8 million € per year.

Environmental Niche and Demographic Modeling of American Chestnut near its Southwestern Range Limit

The unintentional introduction and rapid spread of chestnut blight (caused by Cryphonectria parasitica (Murr.) Barr) in the early 20th century resulted in the demise of American chestnut (Castanea dentata (Marsh.) Borkh.; Fagaceae) as a major component of forest canopies resulting in negative impacts on eastern forest communities. Research efforts over the last century have documented the persistence of occasional trees and root crown/ stump sprouts throughout much of the species' historic range, providing the basis for ongoing breeding of blight-resistant trees and restoration efforts. Here we use environmental niche modeling to investigate whether environmentally suitable habitat remains for remnant trees throughout the southwestern historical range, and to evaluate the reintroduction potential of this relatively understudied part of the historical distribution. We also use stage-structured matrix projection models to investigate the potential demographic future of C. dentata near the historical southwestern range limit based on observations of American chestnut in these areas over the last several decades. We found suitable upland habitat with areas of high forest canopy cover occurs throughout much of the southwestern portion of the historical range and that populations of American chestnut in these areas are predicted to drastically decline over the coming decades. These results highlight the continued presence of suitable C. dentata habitat throughout the southwestern extent of its historical distribution, which should be incorporated into evaluations for future reintroduction, and emphasize the need for efforts to locate, conserve, and introduce genetic material from individuals with locally adapted genotypes into active restoration programs.

Demographic uncertainty and disease risk influence climate‐informed management of an alpine species

AbstractClimate change is expected to disproportionately affect species occupying ecosystems with relatively hard boundaries, such as alpine ecosystems. Wildlife managers must identify actions to conserve and manage alpine species into the future, while considering other issues and uncertainties. Climate change and respiratory pathogens associated with widespread pneumonia epidemics in bighorn sheep (Ovis canadensis) may negatively affect mountain goat (Oreamnos americanus) populations. Mountain goat demographic and population data are challenging to collect and sparsely available, making population management decisions difficult. We developed predictive models incorporating these uncertainties and analyzed results within a structured decision making framework to make management recommendations and identify priority information needs in Montana, USA. We built resource selection models to forecast occupied mountain goat habitat and account for uncertainty in effects of climate change, and a Leslie matrix projection model to predict population trends while accounting for uncertainty in population demographics and dynamics. We predicted disease risks while accounting for uncertainty about presence of pneumonia pathogens and risk tolerance for mixing populations during translocations. Our analysis predicted that new introductions would produce more area occupied by mountain goats at mid‐century, regardless of the effects of climate change. Population augmentations, carnivore management, and harvest management may improve population trends, although this was associated with considerable uncertainty. Tolerance for risk of disease transmission affected optimal management choices because translocations are expected to increase disease risks for mountain goats and sympatric bighorn sheep. Expected value of information analyses revealed that reducing uncertainty related to population dynamics would affect the optimal choice among management strategies to improve mountain goat trends. Reducing uncertainty related to the presence of pneumonia‐associated pathogens and consequences of mixing microbial communities should reduce disease risks if translocations are included in future management strategies. We recommend managers determine tolerance for disease risks associated with translocations that they and constituents are willing to accept. From this, an adaptive management program can be constructed wherein a portfolio of management actions are chosen based on risk tolerance in each population range, combined with the amount that uncertainty is reduced when paired with monitoring, to ultimately improve achievement of fundamental objectives.

Conceptual and methodological issues in structured population models of plants

Structured projection models (SPMs) are a powerful tool to investigate the dynamics of structured populations, which makes them ideal for the study of plant species spanning their range of life forms, sizes, longevity, and life cycle complexity. They are one of the most versatile tools in plant ecology, with hundreds of species studied so far and a wide variety of alternative formulations for different questions and purposes. We revise some of the most salient conceptual and methodological issues in the construction and use of SPMs including both discrete matrix projection models and continuous integral projection models. Consideration is given to the selection of the state variable and the estimation of parameters, especially those involving transitions difficult to observe in the field, such as the quantification of offspring production and the rarely observed mortality of individuals towards the end of the life cycle. Due to the growing importance of investigating population trends in a rapidly changing world, we highlight the use of SPMs for populations under a variety of environmental influences and/or away from their expected equilibrium. The presumed role of population density receives special attention because it often correlates with features of the environment, thus potentially confounding the two effects. Similarly, disentangling the various environmental effects poses challenges of its own, making it difficult to prove causality. The alternatives available are illustrated considering the selection of variables, samples, and model type suitable for specific purposes.

Pitfalls to avoid in nonlinear perturbation analysis of structured population models

AbstractDespite the ubiquity of nonlinear functional relationships in nature we tend to characterize mechanisms in science using more tractable linear functions. In demographic modeling, transfer function analysis is used to calculate the nonlinear response of population growth rate to a theoretical perturbation of one or more matrix elements. This elegant approach is not yet popular in ecology. Inconveniently, using transfer function without care can produce erroneous results without warning. We used a large matrix projection model database to explore the potential pitfalls to be avoided in using transfer function analysis. We asked a fundamental population control question, what matrix element perturbation would be needed to reach a minimum goal of replacement population growth? We then tracked instances in which transfer function yields erroneous output and explored these cases in detail to measure how frequently it occurs. We developed a phylogenetically‐corrected mixed effects logistic regression model in a Bayesian framework to test the effect of species traits and the identity of matrix elements on the probability that transfer function yields errors. We found in 16% of cases the transfer function yielded erroneous outcomes. These errors were more likely when perturbing demographic stasis and also for shrubs more than any other life form. Errors in transfer function analysis were often due to perturbing matrix elements beyond their biological limits, even when this is still mathematically correct. To use transfer function analysis properly in demographic modeling and avoid erroneous results, input must be carefully selected to include only a biologically admissible set of perturbations.

Projection Matrix Models: A Suitable Approach for Predicting Sustainable Growth in Uneven-Aged and Mixed Hyrcanian Forests

The Hyrcanian forests of Iran are mainly managed with the single-selection silvicultural technique. Despite significant ecological benefits associated with selection cutting, this type of forest management leads towards more challenging situations where it is difficult to maintain and practice successful forestry than in even-aged systems. Therefore, this study provides relevant management tools in the form of models to estimate low growth levels in Hyrcanian forests. In the present study, estimation of the population growth rate and then the allowable cut rate of these forests using a matrix model have been calculated in the Gorazbon district. For this purpose, the data of 256 permanent sample plots measured during the years between 2003 and 2012, as well as the data recorded about the trees harvested according to the forestry plan, have been used. As a first step, the most frequently occurring tree species were divided into four groups (beech, hornbeam, chestnut-leaved oak, and other species). Compartments of the district were divided into two groups of logged and unlogged compartments. The purpose of this division was to estimate the allowable cut and compare its volume with the volumes of observed and predicted allowable cuts obtained from forestry plans. The results showed that the total operated allowable cut (OAC) in logged compartments was more than the estimated allowable cut (EAC). In unlogged compartments, the total predicted allowable cut (PAC) was more than EAC. A comparison of EAC and OAC showed that hornbeam has been harvested more than its potential. However, chestnut-leaved oak and other species group have depicted opposite trends. Our models provide important advancements for estimating allowable cut that can enhance the goal of practicing sustainable forestry.

Demographic correction—A tool for inference from individuals to populations

Abstract Estimation of responses of organisms to their environment using experimental manipulations, and comparison of such responses across sets of species, is one of the primary tools in ecology research. The most common approach is to compare the response of a single life stage of species to an environmental factor and use this information to draw conclusions about population dynamics of these species. Such approach ignores the fact that interspecific fitness differences measured at a single life stage are not directly comparable and cannot be extrapolated to lifetime fitness of individuals and thus species’ population dynamics. Comparison of one life stage only while omitting demographic information can strongly bias conclusions, both in experimental studies with a few species and in large comparative studies. We illustrate the effect of this omission using both an exaggerated fictitious example and biological data on congeneric species differing in their demography. We are showing, taking simple assumptions, that different demography can completely revert conclusions reached by a comparison based on an experiment focusing on a single life stage. We show that a ‘demographic correction’, namely translating observed effects into differences in outcomes of demographic models, is a solution to this problem. It requires turning the detected effects from the experiment into changes of transition probabilities of projection matrix models. Although such solution is limited by the low number of species with demographic data available, we believe that existing data (and data likely to be collected in the near future) permit at least approximate handling of this problem. Read the free Plain Language Summary for this article on the Journal blog.

Demographic and life history traits explain patterns in species vulnerability to extinction.

As ecosystems face disruption of community dynamics and habitat loss, the idea of determining ahead of time which species can become extinct is an important subject in conservation biology. A species’ vulnerability to extinction is dependent upon both intrinsic (life-history strategies, genetics) and extrinsic factors (environment, anthropogenic threats). Studies linking intrinsic traits to extinction risk have shown variable results, and to our knowledge, there has not been a systematic analysis looking at how demographic patterns in stage-specific survival and reproductive rates correlate to extinction risk. We used matrix projection models from the COMPADRE and COMADRE matrix databases and IUCN Red List status as our proxy of extinction risk to investigate if some demographic patterns are more vulnerable to extinction than others. We obtained data on demographic rates, phylogeny, and IUCN status for 159 species of herbaceous plants, trees, mammals, and birds. We calculated 14 demographic metrics related to different aspects of life history and elasticity values and analyzed whether they differ based on IUCN categories using conditional random forest analysis and phylogenetic generalized least square regressions. We mapped all species within the database, both with IUCN assessment and without, and overlaid them with biodiversity hotspots to investigate if there is bias within the assessed species and how many of the non-assessed species could use the demographic information recorded in COMPADRE and COMADRE for future IUCN assessments. We found that herbaceous perennials are more vulnerable when they mature early and have high juvenile survival rates; birds are more vulnerable with high progressive growth and reproduction; mammals are more vulnerable when they have longer generation times. These patterns may be used to assess relative vulnerability across species when lacking abundance or trend data.

A critical comparison of integral projection and matrix projection models for demographic analysis: Comment.

A critical comparison of integral projection and matrix projection models for demographic analysis: Comment.

Demographic Modeling Refines Assessment of Three Populations of a Long-Lived Threatened Plant

Structured demographic models can be valuable for assessing the status of at-risk plant species and for guiding efforts to protect and manage them, but they may be infrequently employed in assessments of species of conservation concern because they require data that are not often available to those charged with management. We constructed and analyzed matrix projection models for three populations of the threatened perennial plant species Euphorbia telephioides to reevaluate a prior assessment of stable status and to compare the conclusions of models based on different amounts of data. In contrast to the prior assessment, all of our models predicted population decline for all three populations. Projected growth rates were similar for models based on sparse sampling and those based on a larger more representative sample of individuals, but the models supported contrasting patterns of the sensitivity of population growth rate to individual demographic transitions. Models based on more complete data supported greater elasticity of growth rate to the demographic fates of small non-flowering plants, which had among the lowest elasticity values for models based on more sparse data. We conclude that even models based on limited data can be useful to species status assessments, but that more complete data may be necessary to identify targets for effective management.

Review and Synthesis of Estimated Vital Rates for Terrestrial Salamanders in the Family Plethodontidae

Population models depend on reliable estimates of vital rates, yet for many taxa, such estimates and how they vary in response to spatial or temporal environmental gradients are lacking. The goal of this review was to determine whether existing estimates of vital rates for temperate, direct-developing plethodontid salamanders (subfamily Plethodontinae) could be used to reasonably project values for populations or species where such estimates are lacking, or whether current estimates are biased in a manner that limits their utility. We synthesized current knowledge of stage-specific survival rates, age- and size-at-maturity at first clutch, and clutch frequency. We tested for expected correlations among published vital rates (e.g., age at maturity and survival) and between vital rates and factors such as body size or latitude. We used matrix projection models to judge whether published estimates were reasonably possible for stable salamander populations. The largest number of published vital rates were for clutch size, clutch frequency (proportion of females with clutches), size at maturity or first clutch, and age at maturity or first clutch, though the latter vital rate is primarily inferred from size distribution and growth rate data. Among these vital rates, we found expected correlations with body size and latitude suggesting these rates were reasonable and somewhat predictable among species or populations. In contrast, there were few estimates of egg hatch rate or juvenile or adult survival. Hatch and survival rate estimates were widely variable; estimates seldom included measures of uncertainty, but when uncertainty measurements were included, they were generally high. Based on projection models, few survival estimates were likely unbiased or realistic for stable populations given other salamander vital rates. Additionally, few studies quantified how vital rates vary with spatial or temporal environmental gradients. We outline the key knowledge gaps that limit basic demographic modeling of these remarkably common, influential, and otherwise well-studied salamanders, and make recommendations for future research efforts.

Modeling the persistence of plant populations in fragmented ecosystems

Ecosystem fragmentation is one of the main threats to species persistence via habitat reduction and isolation which often lead to species extinctions. A question that has long been of interest is the minimum habitat size that can sustain viable populations in fragmented landscape. Despite numerous empirical and theoretical efforts on this topic, most studies fail to address this central question, and our mechanistic understanding of and capacity to predict the effects and outcomes associated with fragmentation stressor is still illusive. We develop an ordinary differential equation (ODE) based framework that incorporates the effect of the patch area on the net population growth rate for a plant species in fragmented ecosystem via a general net growth function. We investigate the minimum patch area needed to sustain a given plant species. We use data from the Amazonian herb Heliconia acuminata to test our model. Furthermore, we compare the performance ODE model and a linear matrix model to predict the observed data. We provide a general formula for a threshold value for the fragment area, below which a plant population is not viable. For Heliconia acuminata, our ODE-based model predicts a value for the minimum fragment area of ≈0.7ha, which reflects the observed data and is smaller than the value obtained using the matrix projection model. Our findings suggest that the Heliconia’s mortality rate responds more negatively to fragmentation. Furthermore, we found that the ODE-based model can serve as an alternative to the linear demographic model.

Demystifying individual heterogeneity.

Among-individual variation in vital rates, such as mortality and birth rates, exists in nearly all populations. Recent studies suggest that this individual heterogeneity produces substantial life-history and fitness differences among individuals, which in turn scale up to influence population dynamics. However, our ability to understand the consequences of individual heterogeneity is limited by inconsistencies across conceptual frameworks in the field. Studies of individual heterogeneity remain filled with contradicting and ambiguous terminology that introduces risks of misunderstandings, conflicting models and unreliable conclusions. Here, we synthesise the existing literature into a single and comparatively straightforward framework with explicit terminology and definitions. This work introduces a distinction between potential vital rates and realised vital rates to develop a coherent framework that maps directly onto mathematical models of individual heterogeneity. We suggest the terms "fixed condition" and "dynamic condition" be used to distinguish potential vital rates that are permanent from those that can change throughout an individual's life. To illustrate, we connect the framework to quantitative genetics models and to common classes of statistical models used to infer individual heterogeneity. We also develop a population projection matrix model that provides an example of how our definitions are translated into precise quantitative terms.

Fires slow population declines of a long-lived prairie plant through multiple vital rates.

In grasslands worldwide, modified fire cycles are accelerating herbaceous species extinctions. Fire may avert population declines by increasing survival, reproduction, or both. Survival and growth after fires may be promoted by removal of competitors or biomass and increasing resource availability. Fire-stimulated reproduction may also contribute to population growth through bolstered recruitment. We quantified these influences of fire on population dynamics in Echinacea angustifolia, a perennial forb in North American tallgrass prairie. We first used four datasets, 7-21years long, to estimate fire's influences on survival, flowering, and recruitment. We then used matrix projection models to estimate growth rates across several burn frequencies in five populations, each with one to four burns over 15years. Finally, we estimated the contribution of fire-induced changes in each vital rate to changes in population growth. Population growth rates generally increased with burning. The demographic process underpinning these increases depended on juvenile survival. In populations with high juvenile survival, fire-induced increases in seedling recruitment and juvenile survival enhanced population growth. However, in populations with low juvenile survival, small changes in adult survival drove growth rate changes. Regardless of burn frequencies, our models suggest populations are declining and that recruitment and juvenile survival critically influence population response to fire. However, crucially, increased seedling recruitment only increases population growth rates when enough new recruits reach reproductive maturity. The importance of recruitment and juvenile survival is especially relevant for small populations in fragmented habitats subject to mate-limiting Allee effects and inbreeding depression, which reduce recruitment and survival, respectively.