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1. The histories of individuals impact the dynamics of their populations. Matrix projection models (MPMs) are used to analyse population dynamics, but are not structured to incorporate these influe ...

Increased anthropogenic influence on the environment has accentuated the need to assess how climate and other environmental factors drive vital rates and population dynamics of different types of organisms. However, to allow distinction between the effects of multiple correlated variables, and to capture the effects of rare and extreme climatic conditions, studies extending over decades are often necessary. In this study, we used an individual-based dataset collected in three populations of Pulsatilla vulgaris subsp. gotlandica during 34 years, to explore the effects of variation in precipitation and temperature on vital rates and population dynamics. Most of the observed conspicuous variation in flowering among years was associated with differences in precipitation and temperature in the previous summer and autumn with a higher incidence of flowering following summers with high precipitation and low temperatures. In contrast, climatic variables had no significant effects on individual growth or survival. Although the weather-driven variation in flowering had only moderate absolute effects on the population growth rate, simulated persistent changes in average precipitation and temperature resulted in considerable reductions in population sizes compared with current conditions. Analyses carried out with subsets of data consisting of 5 and 10 years yielded results that strongly deviated from those based on the full dataset. Synthesis. The results of this study illustrate the importance of long-term demographic monitoring to identify key climatic variables affecting vital rates and driving population dynamics in long-lived organisms.

Phenotypic plasticity can mask population genetic differentiation, reducing the predictability of trait-environment relationships. In short-lived plants, reproductive traits may be more genetically determined due to their direct impact on fitness, whereas vegetative traits may show higher plasticity to buffer short-term perturbations. Combining a multi-treatment greenhouse experiment with global field observations for the short-lived Plantago lanceolata, we 1) disentangled the genetic and plastic responses of functional traits to a set of environmental drivers and 2) assessed the utility of trait-environment relationshisps inferred from observational data for predicting genetic differentiation. Reproductive traits showed distinct genetic differentiation that was highly predictable from observational data, but only when correcting traits for differences in their (labile) biomass component. Vegetative traits showed higher plasticity and contrasting genetic and plastic responses, leading to unpredictable trait patterns. Our study suggests that genetic differentiation may be inferred from observational data only for the traits most closely related with fitness.

To understand how the environment drives spatial variation in population dynamics, we need to assess the effects of a large number of potential drivers on the vital rates (survival, growth and reproduction), and explore these relationships over large geographical areas and long environmental gradients. In this study, we examined the effects of a broad variety of abiotic and biotic environmental factors, including intraspecific density, on the demography of the forest understory herbActaea spicatabetween 2017 and 2019 at 40 sites across Sweden, including the northern range margin of its distribution. We assessed the effect of potential environmental drivers on vital rates using generalized linear mixed models (GLMMs), and then quantified the impact of each important driver on population growth rate (λ) using integral projection models (IPMs). Population dynamics ofA. spicatawere mostly driven by environmental factors affecting survival and growth, such as air humidity, soil depth and forest tree species composition, and thus those drivers jointly determined the realized niche of the species. Soil pH had a strong effect on the flowering probability, while the effect on population growth rate was relatively small. In addition to identifying specific drivers forA. spicata’spopulation dynamics, our study illustrates the impact that spatial variation in environmental conditions can have on λ. Assessing the effects of a broad range of potential drivers, as done in this study, is important not only to quantify the relative importance of different drivers for population dynamics but also to understand species distributions and abundance patterns.

Significance Knowing which of multiple environmental factors (climate, other species, humans, etc.) most strongly affect wild plants and animals could focus our attention on the future environmental changes most likely to influence biodiversity. However, we find that abiotic, biotic, and human influences on plant populations are of similar strengths, for different kinds of plants and in multiple locations and environments. The effects of these factors on plant evolution are also likely to be similar. Thus, there is unlikely to be a shortcut to considering all of these factors when predicting the future ecological and evolutionary responses of species and of biodiversity to environmental changes., Multiple, simultaneous environmental changes, in climatic/abiotic factors, interacting species, and direct human influences, are impacting natural populations and thus biodiversity, ecosystem services, and evolutionary trajectories. Determining whether the magnitudes of the population impacts of abiotic, biotic, and anthropogenic drivers differ, accounting for their direct effects and effects mediated through other drivers, would allow us to better predict population fates and design mitigation strategies. We compiled 644 paired values of the population growth rate (λ) from high and low levels of an identified driver from demographic studies of terrestrial plants. Among abiotic drivers, natural disturbance (not climate), and among biotic drivers, interactions with neighboring plants had the strongest effects on λ. However, when drivers were combined into the 3 main types, their average effects on λ did not differ. For the subset of studies that measured both the average and variability of the driver, λ was marginally more sensitive to 1 SD of change in abiotic drivers relative to biotic drivers, but sensitivity to biotic drivers was still substantial. Similar impact magnitudes for abiotic/biotic/anthropogenic drivers hold for plants of different growth forms, for different latitudinal zones, and for biomes characterized by harsher or milder abiotic conditions, suggesting that all 3 drivers have equivalent impacts across a variety of contexts. Thus, the best available information about the integrated effects of drivers on all demographic rates provides no justification for ignoring drivers of any of these 3 types when projecting ecological and evolutionary responses of populations and of biodiversity to environmental changes.

Temporal variation in natural selection has profound effects on the evolutionary trajectories of populations. One potential source of variation in selection is that differences in thermal reaction norms and temperature influence the relative phenology of interacting species. We manipulated the phenology of the butterfly herbivore Anthocharis cardamines relative to genetically identical populations of its host plant, Cardamine pratensis, and examined the effects on butterfly preferences and selection acting on the host plant. We found that butterflies preferred plants at an intermediate flowering stage, regardless of the timing of butterfly flight relative to flowering onset of the population. Consequently, the probability that plant genotypes differing in timing of flowering should experience a butterfly attack depended strongly on relative phenology. These results suggest that differences in spring temperature influence the direction of herbivore-mediated selection on flowering phenology, and that climatic conditions can influence natural selection also when phenotypic preferences remain constant.

AimRange shifts are expected to occur when populations at one range margin perform better than those at the other margin, yet no global trend in population performances at range margins has been demonstrated empirically across a wide range of taxa and biomes. Here we test the prediction that, if impacts of ongoing climate change on population performance are widespread, then populations from the high-latitude margin (HLM) should perform as well as or better than central populations, whereas populations at low-latitude margins (LLM) populations should perform worse.LocationGlobalTime period1898–2020Major taxa studiedPlants and animalsMethodsTo test our prediction, we used a meta-analysis quantifying the empirical support for asymmetry in the performance of high- and low-latitude margin populations compared to central populations. Performance estimates were derived from 51 papers involving 113 margin-centre comparisons from 54 species and 705 populations. We then related these performance differences to climatic differences among populations. We also tested whether patterns are consistent across taxonomic kingdoms (plants vs. animals) and across habitats (marine vs. terrestrial).ResultsPopulations at margins performed significantly worse than central populations and this trend was primarily driven by the low-latitude margin. Although the difference was of small magnitude, it was largely consistent across biological kingdoms and habitats. The differences in performance were positively related to the difference in average temperatures between populations during the period 1985–2016.Major conclusionsThe observed asymmetry in marginal population performance confirms predictions about the effects of global climate change. It indicates that changes in demographic rates in marginal populations, despite extensive short-term variation, can serve as early-warning signals of impending range shifts.

Time lags in responses of organisms to deteriorating environmental conditions delay population declines and extinctions. We examined how local processes at the population level contribute to extinction debt, and how cycles of habitat deterioration and recovery may delay extinction. We carried out a demographic analysis of the fate of the grassland perennial Primula veris after the cessation of grassland management, where we used either a unidirectional succession model for forest habitat or a rotation model with a period of forest growth followed by a clear-cut and a new successional cycle. The simulations indicated that P. veris populations may have an extinction time of decades to centuries after a detrimental management change. A survey of the current incidence and abundance of P. veris in sites with different histories of afforestation confirmed the simulation results of low extinction rates. P. veris had reduced incidence and abundance only at sites with at least 100 years of forest cover. Time to extinction in simulations was dependent on the duration of the periods with favourable and unfavourable conditions after management cessation, and the population sizes and growth rates in these periods. Our results thus suggest that the ability of a species to survive is a complex function of disturbance regimes, rates of successional change, and the demographic response to environmental changes. Detailed demographic studies over entire successional cycles are therefore essential to identify the environmental conditions that enable long-term persistence and to design management for species experiencing extinction debts.

Timing of plant development both determines the abiotic conditions that the plant experiences and strongly influences the intensity of interactions with other organisms. Plants and herbivores differ in their response to environmental cues, and spatial and temporal variation in environmental conditions might influence the synchrony between host plants and herbivores, and the intensity of their interactions. We investigated whether differences in first day of flowering among and within 21 populations of the polyploid herb Cardamine pratensis influenced the frequency of oviposition by the butterfly Anthocharis cardamines during four study years. The proportion of plants that became oviposited upon differed among populations, but these differences were not related to mean flowering phenology within the population in any of the four study years. Attack rates in the field were also not correlated with resistance to oviposition estimated under controlled conditions. Within populations, the frequency of butterfly attack was higher in early-flowering individuals in two of the four study years, while there was no significant relationship in the other 2 years. Larger plants were more likely to become oviposited upon in all 4 years. The effects of first flowering day and size on the frequency of butterfly attack did not differ among populations. The results suggest that differences in attack intensities among populations are driven mainly by differences in the environmental context of populations while mean differences in plant traits play a minor role. The fact that within populations timing of flowering influenced the frequency of herbivore attack only in some years and suggests that herbivore-mediated selection on plant phenology differs among years, possibly because plants and herbivores respond differently to environmental cues.

Microrefugia are sites that support populations of species when their ranges contract during unfavorable climate episodes. Here, we review and discuss two aspects relevant for microrefugia. First, distributions of different species are influenced by different climatic variables. Second, climatic variables differ in the degree of local decoupling from the regional climate. Based on this, we suggest that only species limited by climatic conditions decoupled from the regional climate can benefit from microrefugia. We argue that this restriction has received little attention in spite of its importance for microrefugia as a mechanism for species resilience (the survival of unfavorable episodes and subsequent range expansion). Presence of microrefugia will depend on both the responses of individual species to local climatic variation and how climate-forcing factors shape the correlation between local and regional climate across space and time.

Variation in mutualistic and antagonistic interactions are important sources of variation in population dynamics and natural selection. Environmental heterogeneity can influence the outcome of interactions by affecting the intensity of interactions, but also by affecting the demography of the populations involved. However, little is known about the relative importance of environmental effects on interaction intensities and demographic sensitivity for variation in population growth rates. We investigated how soil depth, soil moisture, soil nutrient composition, and vegetation height influenced the intensity of seed predation as well as host plant demography and sensitivity to seed predation in the perennial herb Primula farinosa. Intensity of seed predation ranged from 0% to 80% of seeds damaged among the 24 study populations and was related to soil moisture in two of four years. The effect of seed predation on plant population growth rate (lambda) ranged from negligible to a reduction in lambda by 0.70. Sensitivity of population growth rate to predation explained as much of the variation in the reductions in population growth rate due to seed predation as did predation intensity. Plant population growth rate in the absence of seed predation and sensitivity to predation were negatively related to soil depth and soil moisture. Both intensity of predation and sensitivity to predation were positively correlated with potential population growth rate and, as a result, there was no significant relationship between predation intensity and realized population growth rate. We conclude that in our study system environmental context influences the effects of seed predation on plant fitness and population dynamics in two important ways: through variation in interaction intensity and through sensitivity to the effects of this interaction. Moreover, our results show that a given abiotic factor can influence population growth rate in different directions through effects on potential growth rate, intensity of biotic interactions, and the sensitivity of population growth rate to interactions.

Uncertainty associated with ecological forecasts has long been recognized, but forecast accuracy is rarely quantified. We evaluated how well data on 82 populations of 20 species of plants spanning ...

Accepted manuscript version. Published version available at https://doi.org/10.1016/j.ppees.2017.09.008. Accepted manuscript version, licensed CC BY-NC-ND 4.0. In the face of climate change, populations have two survival options − they can remain in situ and tolerate the new climatic conditions (“stay”), or they can move to track their climatic niches (“go”). For sessile and small-stature organisms like alpine plants, staying requires broad climatic tolerances, realized niche shifts due to changing biotic interactions, acclimation through plasticity, or rapid genetic adaptation. Going, in contrast, requires good dispersal and colonization capacities. Neither the magnitude of climate change experienced locally nor the capacities required for staying/going in response to climate change are constant across landscapes, and both aspects may be strongly affected by local microclimatic variation associated with topographic complexity. We combine ideas from population and community ecology to discuss the effects of topographic complexity in the landscape on the immediate “stay” or “go” opportunities of local populations and communities, and on the selective pressures that may have shaped the stay or go capacities of the species occupying contrasting landscapes. We demonstrate, using example landscapes of different topographical complexity, how species’ thermal niches could be distributed across these landscapes, and how these, in turn, may affect many population and community ecological processes that are related to adaptation or dispersal. Focusing on treeless alpine or Arctic landscapes, where temperature is expected to be a strong determinant, our theorethical framework leads to the hypothesis that populations and communities of topographically complex (rough and patchy) landscapes should be both more resistant and more resilient to climate change than those of topographically simple (flat and homogeneous) landscapes. Our theorethical framework further points to how meta-community dynamics such as mass effects in topographically complex landscapes and extinction lags in simple landscapes, may mask and delay the long-term outcomes of these landscape differences under rapidly changing climates.

Mutualistic and antagonistic interactions with animals are known to influence the performance of plants in many ways. Much less is known about how such effects are influenced by the environment and how they translate into effects on plant population dynamics. In this study, we first quantified how pre-dispersal seed predation in the perennial herb Primula veris changes along a continuous gradient of canopy cover. We then used a deterministic demographic modeling approach to investigate how seed predation may influence population growth rate (λ) and how effects depend on environmentally-induced variation in plant demography. Intensity of seed predation increased with the degree of canopy cover, while sensitivity of λ to changes in seed production decreased. This translated into non-linear effects of seed predation on λ along the canopy cover gradient. Despite seed predation rates being highest in closed habitats, the negative effect of seed predation on λ was lower here than in slightly more open habitats. Our results demonstrate that knowledge of the intensity of plant-herbivore interactions does not suffice to infer how animals influence the population dynamics of plants and their distribution. Plant demographic sensitivity and its dependence on the environment need also to be taken into account when assessing the importance of plant-animal interactions. © Oikos.

Identifying the internal and external drivers of population dynamics is a key objective in ecology, currently accentuated by the need to forecast the effects of climate change on species distributions and abundances. The interplay between environmental and density effects is one particularly important aspect of such forecasts. We examined the simultaneous impact of climate and intraspecific density on vital rates of the dwarf shrub Fumana procumbens over 20 yr, using generalized additive mixed models. We then analyzed effects on population dynamics using integral projection models. The population projection models accurately captured observed fluctuations in population size. Our analyses suggested the population was intrinsically regulated but with annual fluctuations in response to variation in weather. Simulations showed that implicitly assuming variation in demographic rates to be driven solely by the environment can overestimate extinction risks if there is density dependence. We conclude that density regulation can dampen effects of climate change on Fumana population size, and discuss the need to quantify density dependence in predictions of population responses to environmental changes.

7 páginas, 3 figuras, 1 tabla.-- El documento en word es la versión de autor., To accurately estimate population dynamics and viability, structured population models account for among-individual differences in demographic parameters that are related to individual state. In the widely used matrix models, such differences are incorporated in terms of discrete state categories, whereas integral projection models (IPMs) use continuous state variables to avoid artificial classes. In IPMs, and sometimes also in matrix models, parameterization is based on regressions that do not always model nonlinear relationships between demographic parameters and state variables. We stress the importance of testing for nonlinearity and propose using restricted cubic splines in order to allow for a wide variety of relationships in regressions and demographic models. For the plant Borderea pyrenaica, we found that vital rate relationships with size and age were nonlinear and that the parameterization method had large effects on predicted population growth rates, λ (linear IPM, 0.95; nonlinear IPMs, 1.00; matrix model, 0.96). Our results suggest that restricted cubic spline models are more reliable than linear or polynomial models. Because even weak nonlinearity in relationships between vital rates and state variables can have large effects on model predictions, we suggest that restricted cubic regression splines should be considered for parameterizing models of population dynamics whenever linearity cannot be assumed., This study was financially supported by the Strategic Research Programme EkoKlim at Stockholm University (J.P.D.), the National Parks project (ref 018/2008) (M.B.G), and the Swedish Research Council for Environment, Agricultural Sciences and Spatial Planning (FORMAS) (J.E.).

Despite seemingly obvious effects of environmental drivers, mechanisms behind long-term changes in plant population sizes over time are often poorly known. We investigated how soil potassium concentration and seed predation are likely to change over time as a result of succession from deciduous forest to spruce forest, and how this affects population trajectories of Actaea spicata. Observations and addition experiments showed that high soil potassium concentration increased individual growth rates. Among-site comparisons showed that soil potassium concentration was lower where proportion spruce was higher. Incorporation of a gradual increase in spruce over time in an integral projection model where individual growth depended on potassium suggested a net decrease in A. spicata population sizes over forest succession. This result suggests that small changes in factors with small effects on individual performance can influence patterns of species occupancy along successional gradients. We incorporated also density independent and density dependent effects of pre-dispersal seed predation over succession into the same model. Seed predation influenced the tree composition at which A. spicata population growth was positive. However, significant effects of A. spicata population size on seed predation intensity did not translate into important feedback effects on population growth trajectories over succession. Our results illustrate how demographic models can be used to gain understanding of the mechanisms behind effects of environmental change on species abundances and distributions by the simultaneous inclusion of changing abiotic and biotic factors.

Matrix projection models are among the most widely used tools in plant ecology. However, the way in which plant ecologists use and interpret these models differs from the way in which they are presented in the broader academic literature. In contrast to calls from earlier reviews, most studies of plant populations are based on < 5 matrices and present simple metrics such as deterministic population growth rates. However, plant ecologists also cautioned against literal interpretation of model predictions. Although academic studies have emphasized testing quantitative model predictions, such forecasts are not the way in which plant ecologists find matrix models to be most useful. Improving forecasting ability would necessitate increased model complexity and longer studies. Therefore, in addition to longer term studies with better links to environmental drivers, priorities for research include critically evaluating relative/comparative uses of matrix models and asking how we can use many short-term studies to understand long-term population dynamics.

Negative effects of habitat fragmentation on individual performance have been widely documented, but relatively little is known about how simultaneous effects on multiple vital rates translate into effects on population viability in long-lived species. In this study, we examined relationships between population size, individual growth, survival and reproduction, and population growth rate in the perennial plant Phyteuma spicatum. Population size positively affected the growth of seedlings, the survival of juveniles, the proportion of adults flowering, and potential seed production. Analyses with integral projection models, however, showed no relationship between population size and population growth rate. This was due to the fact that herbivores and pathogens eliminated the relationship between population size and seed production, and that population growth rate was not sensitive to changes in the vital rates that varied with population size. We conclude that effects of population size on vital rates must not translate into effects on population growth rate, and that populations of long-lived organisms may partly be able to buffer negative effects of small population size on vital rates that have a relatively small influence on population growth rate. Our study illustrates that we need to be cautious when assessing the consequences of habitat fragmentation for population viability based on effects on only one or a few vital rates.

Explaining variation in population growth rates is fundamental to predicting population dynamics and population responses to environmental change. In this study, we used matrix population models, which link birth, growth and survival to population growth rate, to examine how and why population growth rates vary within and among 50 terrestrial plant species. Population growth rates were more similar within species than among species; with phylogeny having a minimal influence on among-species variation. Most population growth rates decreased over the observation period and were negatively autocorrelated between years; that is, higher than average population growth rates tended to be followed by lower than average population growth rates. Population growth rates varied more through time than space; this temporal variation was due mostly to variation in post-seedling survival and for a subset of species was partly explained by response to environmental factors, such as fire and herbivory. Stochastic population growth rates departed from mean matrix population growth rate for temporally autocorrelated environments. Our findings indicate that demographic data and models of closely related plant species cannot necessarily be used to make recommendations for conservation or control, and that post-seedling survival and the sequence of environmental conditions are critical for determining plant population growth rate.

Summary 1. In the understorey herb Lathyrus vernus seed production is pollen limited, but increased reproduction results in a lower probability of remaining reproductive. Putting these two results together, previous research reported that population growth rate λ was negatively impacted by high pollination. 2. Thus, costs and benefits have to be translated into the common currency of their respective effects on population dynamics to determine whether populations are truly pollen limited or whether they are already at an optimal level of pollination. 3. Also, when pollinators and demography vary from year to year we require a framework that examines reproductive benefits and demographic costs in the context of a variable environment. Whether or not additional pollination will increase the stochastic population growth rate λS depends upon the balance of stochastic elasticities of the costs and benefits. 4. In constant environment models, where seed survival, germination and seedling survival were increased, we found that the high cost of reproduction could be offset by improvements in seed survival and germination, but not by improvements of seedling survival. 5. In variable environment models, where changes in the sequence and frequencies of high- and low-pollination years mixed with occasional high-germination years were modelled, we found that increasing the frequency of high-germination conditions could offset the cost of reproduction, and the offset was even greater if high-germination years occurred after a high-pollination year or if high pollination was accompanied by high-germination conditions in the same year. 6. Both deterministic λ and stochastic λS were less sensitive to perturbation of reproduction than to perturbation of the probability for flowering plants to remain reproductive. In other words, a small change in the parameter which is related to the ‘cost’ of reproduction had a bigger effect than a small change in the parameter which is related to the ‘benefit’ of increased pollination for Lathyrus. 7.Synthesis. Stochastic environment-specific elasticities for reproduction and stasis of flowering plants differ in their response to environmental context. The cost–benefit relationships, the ultimate fitness consequences of supplemental pollen, are influenced by the frequency and sequence of years differing in pollen availability and recruitment conditions.

In heterogeneous environments, selection on life-history traits and flowering time may vary considerably among populations because of differences in the extent to which mortality is related to age or size, and because of differences in the seasonal patterns of resource availability and intensity of biotic interactions. Spatial variation in optimal reproductive effort and flowering time may result in the evolution of genetic differences in life-history traits, but also in the evolution of adaptive phenotypic plasticity. The perennial herb Primula farinosa occurs at sites that differ widely in soil depth and therefore in water-holding capacity, vegetation cover, and frost-induced soil movement in winter. We used data from eight natural populations and a common-garden experiment to test the predictions that reproductive allocation is negatively correlated with soil depth while age at first reproduction and first flowering date among reproductive individuals are positively correlated with soil depth. In the common-garden experiment, maternal families collected in the field were grown from seed and monitored for 5 years. In the field, reproductive effort (number of flowers in relation to rosette area) varied among populations and was negatively related to soil depth. In the common-garden experiment, among-population differences in age at first reproduction, and reproductive effort were statistically significant, but relatively small and not correlated with soil depth at the site of origin. Flowering time varied considerably among populations, but was not related to soil depth at the site of origin. Taken together, the results suggest that among-population variation in reproductive effort observed in the field largely reflects phenotypic plasticity. They further suggest that among-population differentiation in flowering time cannot be attributed to variation in environmental factors correlated with soil depth.

Sweden. Fluctuations of resources in time and space will influence not only species abundance but also interactions among species. For plantconsumer interactions, the effects of resource variation have mostly been studied in systems with high resource variability. Systems with moderate variations are less studied, although ecological and evolutionary dynamics of plants and consumers are likely to be affected also by less extreme variability. The effects of variation in a particular resource should depend on consumer diet width. We examined how spatial and temporal variation in seed production in the perennial herb Lathyrus vernus influenced population dynamics and resource utilization in two beetle pre-dispersal seed predators with different host ranges over six years. The monophagous Apion opeticum occupied fewer patches and had lower densities than the oligophagous Bruchus atomarius. The proportion of seeds attacked increased with increases in seed production between years for both seed predators. A possible explanation for these patterns is that population dynamics of beetles are driven largely by local factors and that the same factors influence both beetle performance and seed production. In B. atomarius, patterns may also be influenced by a more pronounced preference for L. vernus in years with a high seed production in L. vernus .W e conclude that relatively modest variation in seed production may result in responses that differ in both direction and extent from those usually observed in systems with high variation in seed production.

Summary 1. Although necessary for understanding and predicting population dynamics, abiotic and biotic interactions have only rarely been coupled to demography and population dynamics. 2. We estimated effects of 11 environmental factors on survival, growth and fertility of the perennial herb Actaea spicata and incorporated significant factors into integral projection models to assess their effect on population dynamics. 3. Statistical models suggested that high soil potassium concentration increased individual growth and that seed predation and, to a lesser extent, canopy cover reduced seed production. 4. Demographic models showed that both soil potassium concentration and pre-dispersal seed predation could reverse population growth from positive to negative. The observed range of soil potassium concentration corresponded to growth rates ( λ ) between 0.96 and 1.07, at mean observed seed predation intensity. At observed mean potassium concentration, growth rate ranged from 0.99 to 1.02 over observed seed predation intensities. 5. Sensitivity of population growth rate to different vital rates strongly influenced the relative effects of the two factors. Elasticity analysis suggested that proportional changes in soil potassium concentration result in seven times larger effects on population growth rate than changes in seed predation. 6. Synthesis . We conclude that relatively weak associations between environmental factors and vital rates can have substantial long-term effects on population growth. Approaches based on detailed demographic models, that simultaneously assess abiotic and biotic effects on population growth rate, constitute important tools for establishing the links between the environment and dynamics of populations and communities.

There is growing evidence that genetic and ecological factors interact in determining population persistence. The demographic effects of inbreeding depression can largely depend on the ecological milieu. We used demographic data of the perennial herb Succisa pratensis from six populations in grazed and ungrazed sites with different soil moisture. We built an individual-based model assessing the demographic consequences of inbreeding depression in populations with different management and habitat. Today this plant has to cope with severe landscape fragmentation, deteriorating habitat conditions in terms of decreasing grazing intensity, and the effects of inbreeding depression. For each population we performed simulations testing two inbreeding depression hypotheses (partial dominance and overdominance) and three epistatic functions among loci. The results indicated stronger inbreeding depression effects for populations in unfavourable sites without grazing or in xeric habitats compared to populations in favourable mesic sites with grazing. Overall, we found stronger effects with overdominance, a result that emphasizes the importance of understanding the genetic mechanisms of inbreeding depression. Hence, management practices can interact with the genetic consequences of inbreeding depression in population dynamics, which may have important implications for plant population ecology and evolutionary dynamics of inbreeding depression, [GER] Es gibt zunehmend Hinweise darauf, dass genetische und okologische Faktoren bei der Bestimmung der Persistenz von Populationen zusammenwirken. Die demographischen Effekte von Inzuchtdepressionen hangen in großem Ausmaß von der okologischen Umwelt ab. Wir nutzten die demographischen Daten des perennierenden Krautes Succisa pratensis aus sechs Populationen, die entweder beweidet oder unbeweidet waren und unterschiedliche Bodenfeuchten zeigten. Wir erstellten ein individuenbasiertes Modell um die demographischen Konsequenzen der Inzuchtdepression in verschiedenen Populationen bei verschiedenen Bewirtschaftungen und Habitaten abzuschatzen. Heute muss diese Pflanze mit ernster Landschaftsfragmentierung, sich verschlechternden Habitatbedingungen in Form von abnehmender Beweidungsintensitat und den Auswirkungen der Inzuchtdepression zurechtkommen. Fur jede Population fuhrten wir Simulationen durch, um zwei Inzuchtdepressions-Hypothesen (teilweise und Uberdominanz) und drei epistatische Funktionen uber die Loci zu testen. Die Ergebnisse wiesen auf starkere Auswirkungen der Inzuchtdepression bei Populationen in ungunstigen Habitaten ohne Beweidung oder in xerischen Habitaten im Vergleich zu Populationen in den bevorzugten mesischen Habitaten mit Beweidung hin. Insgesamt fanden wir starkere Effekte bei Uberdominanz, ein Ergebnis, dass die Wichtigkeit betont, die genetischen Mechanismen der Inzuchtdepression zu verstehen. Die Bewirtschaftungsweise kann also mit den genetischen Konsequenzen der Inzuchtdepression in der Populationsdynamik interagieren. Dies kann wichtige Implikationen fur die Pflanzenpopu- lationsokologie und die evolutionare Dynamik der Inzuchtdepression haben

Only demographic studies can link in a quantitative way observed trends in population growth rate to parts of the life cycle. Population growth rate has been used for some time to assess the overall status of populations in conservation management. More recently there has been an increasing interest in elaborating methods that can assess the relative importance of different life-cycle phases for observed population growth trends (Silvertown et al. 1993, 1996; Caswell 1996a; Royama 1996). This kind of information is essential to identifying critical life-cycle stages and concentrating management efforts on them. One tool that has become widely used to extract information from demographic data is population projection matrices (Caswell 1978, 1989a; van Groenendael et al. 1988; Silvertown et al. 1993, 1996; Schemske et al. 1994). Silvertown et al. (1996) discuss elasticity matrices as a way to identify such critical life-cycle stages and as an aid to constructing rules of thumb useful in plant conservation. They warn against a naive interpretation of elasticities and argue that the state of the populationits rate of increase-must be taken into account. We want to focus attention on some additional problems with the use of elasticity values for identifying key phases of the life cycle and to propose an alternative method that reduces these problems. The rate of increase of a population (X) depends on ageor stage-specific vital rates such as survival, growth, and reproduction. Sensitivity analysis explores this dependence by calculating the effects on X of infinitely small absolute changes to matrix element aij, which represents particular transitions in the life cycle (Caswell 1978, 1989a). Hence, the sensitivity sii of a matrix element aii is

1. In patchily distributed plant species, seed production is likely to be influenced both by local abiotic factors affecting plant size and conditions for fruit maturation, and by population characteristics affecting the intensity of interactions with mutualists and antagonists. However, the relative importance of these effects is poorly known. 2. We used multiple regression and path models to examine the importance of abiotic factors (sun exposure, soil depth) and population characteristics (size, density and connectivity) for variation in flower and fruit production and intensity of seed predation among 39 populations of the long-lived herb Vincetoxicum hirundinaria in three consecutive years. In addition, we manipulated water availability in a field experiment and recorded short-term and long-term effects on fruit output, and conducted a supplemental hand-pollination experiment. 3. Flower production varied little, while fruit initiation, fruit abortion and fruit predation varied considerably among years. Sun exposure and soil depth affected fruit production per plant indirectly and positively through their effects on flower number. Population density affected fruit production negatively through its effect on flower number. Both fruit initiation and the proportion of fruits attacked by the tephritid fly Euphranta connexa were related positively to population size. 4. The number of full-size fruits per plant was related positively to sun exposure and population size in two years each, and related negatively to population density in one year. However, because of seed predation, the number of intact mature fruits was related significantly to population characteristics in only one of three years. 5. The field experiments showed that both shortage of water and insufficient pollination may limit fruit set in V. hirundinaria. 6. Synthesis. These results demonstrate that the relative importance of local abiotic conditions and population characteristics may vary considerably along the chain of events from flower formation to intact fruit, and also among years. They further show that, at least in species with a naturally patchy distribution, connectivity may be relatively unimportant for variation in reproductive output compared to effects of habitat quality, population size and density.

Pre-dispersal seed predation may have important effects on population dynamics and trait evolution in plants. In this review, we first present a conceptual framework of the strength of pre-dispersal seed predation and its variation in space and time. We consider the interaction between plants and their seed predators to be “strong” when it affects plant population dynamics or causes changes in plant trait–fitness relationships, and “weak” when it has no such effects, and propose ways of how to adequately assess these effects. Second, we review the ecological literature between 1991 and 2005 to evaluate documented effects of pre-dispersal seed predation on plants and draw five major conclusions. (1) Pre-dispersal seed predation rates are usually low but sometimes high, and show a considerable variation in space and time. (2) Direct evidence suggests that pre-dispersal seed predation can have a significant effect on recruitment and plant population growth rate. Accumulating evidence of seed-limited recruitment suggests that such effects are common. (3) Pre-dispersal seed predation affects selection on several plant traits, such as flowering phenology and flower number, which are usually interpreted mainly in the context of plant–pollinator interactions. (4) The patterns of variation in the interactions between plants and pre-dispersal seed predators suggest that geographic selection mosaics may be common. (5) Although there are numerous studies estimating seed predation, there are still rather few studies that have aimed at examining the interaction explicitly in terms of effects on plant population dynamics and trait selection. From these we know that seed predators can have important, and often variable, effects on plant population dynamics and trait evolution. However, it still remains to assess how important they are across study systems and relative to other aspects of the plant's biotic and abiotic environment.

Most metapopulation models neglect the local dynamics, and systems characterized by slow population turnover, time lags and non-equilibrium, are only rarely examined within a metapopulation context. In this study we used a realistic, spatially explicit, dynamic metapopulation model of a long-lived grassland plant, Succisa pratensis, to examine the relative importance of local population dynamics, and short and long-distance dispersal of seeds. Using both vegetation composition and sowing experiments we identified 94 occupied and 43 unoccupied, but suitable, habitat patches in a 7-km2 landscape. Local population dynamics were studied in permanent plots in five populations. Simulation results showed that the colonization and extinction dynamics of S. pratensis were slow with about one colonization or extinction per year and the time frame for the population system to attain equilibrium in a constant landscape was several thousands of years. Sensitivity analyses demonstrated that occasional long-distance dispersal had a large influence on population turnover rates whereas regular short-distance dispersal had little effect. Our model also allowed us to assess how demographic processes affect not only local population growth but also regional dynamics. Fecundity was more important, compared with growth and survival, in a metapopulation context than when considered only within populations. The effect of landscape development was examined through different land-use scenarios and suggested that S. pratensis only very slowly colonizes new habitats that are made available. Our results with S. pratensis in an agricultural landscape show that long-distance dispersal and colonization dynamics play an important role for the regional distribution in long-lived plants but that time lags, and thus the effect of landscape history, are also very important.

Population context should influence pollination success and selection on floral display in animal-pollinated plants because attraction of pollinators depends not only on the characteristics of individual plants, but also on the attractiveness of co-occurring conspecifics. The insect-pollinated herb Primula farinosa is polymorphic for inflorescence height. Natural populations may include both long-scaped plants, which present their flowers well above the soil surface, and short-scaped plants, with their flowers positioned close to the ground. We experimentally tested whether seed production in short-scaped P. farinosa varied with local morph frequency and surrounding vegetation height. In tall vegetation, short-scaped plants in polymorphic populations produced more fruit and tended to produce more seeds than short-scaped plants did in monomorphic populations. In low vegetation, population composition did not significantly affect fruit and seed output of short-scaped plants. The results suggest that long-scaped plants facilitate short-scaped plants in terms of pollinator attraction and that the facilitation effect is contingent on the height of the surrounding vegetation. The documented facilitation should contribute to the maintenance of the scape length polymorphism in ungrazed areas where litter accumulates and vegetation grows tall.

Summary Cascading effects from a third level consumer to the basal plant level have been documented several times in terrestrial systems. However, less is known about how these effects are influenced by characteristics of the host plant population. To examine if properties of the spatial context can affect tritrophic interactions we studied 85 populations of a perennial plant, Actaea spicata , the associated specialist moth seed predator, Eupithecia immundata and a guild of parasitoids. Based on the Fretwell–Oksanen model we developed a hypothesis for how the level of herbivory is related to the spatial aggregation of plant populations. In agreement with predictions, incidences of both higher trophic levels were correlated to plant population size. However, there was no effect of population connectivity or environmental parameters. Seed predation was unimodally related to population size with the highest levels in populations of intermediate size. In small populations, usually either a high proportion of seeds was preyed upon due to seed predator presence and parasitoid absence or there was no seed predation when the seed predator was absent. Intermediately sized plant populations suffered from intense seed predation since the seed predator was present but parasitoids were often not. In all large plant populations parasitoids reduced the level of seed predation, thereby enhancing plant fitness. The effects of predation on seed output was correlated with effects on plant population structure, in terms of the proportion of seedlings. Our results demonstrate that host plant population size is important for the distribution of herbivores and their natural enemies, as well as for the outcome of the tritrophic interaction. Moreover, natural enemies of a specialist herbivore might have long-term cascading effects in terms of changes in plant population structure.

Summary 1 We attempt to explain the current distribution of a long-lived perennial plant, Succisa pratensis , in a rural landscape in southern Sweden by linking its population biology with documented changes in the landscape, using a dynamical, spatially explicit model incorporating population dynamics and spatial spreading of the plant. Changes in the landscape were inferred from historical maps (1850 and 1900) and aerial photographs (1945 and 2001). 2 We tested whether predictions for the current species distribution are affected by assumptions about its early 19th century distribution, to determine whether recent history and current processes are dominant, and how past landscape changes determine current distributions. 3 Initial conditions influence predictions of current distribution, suggesting that the current distribution still partly reflects the distribution of the species in the early 19th century. A period of 150 years is too short for Succisa to have spread extensively if dispersal parameters are given realistic values. 4 Simulations in which present-day land-use patterns were imposed at earlier dates showed that changes in landscape structure over the past 175 years also had a strong effect on the present-day habitat occupancy and population sizes of Succisa . 5 The dominant process for Succisa now is extinction from marginal habitats. It is therefore likely that the (relatively) high present-day occupation patterns are still due to much larger areas having been available in the past rather than to successful dispersal. Although the species has responded to landscape changes, there is little evidence of population sizes reaching equilibrium. 6 Our approach shows that the wealth of landscape information available from historical maps can be linked with data on population biology by means of dynamical models that can make predictions about species dynamics.

Summary 1. Matrix population models have become important tools in many fields of ecology and conservation biology, and are the most commonly used method in population viability analysis (PVA). There is a large literature concerned with different aspects of matrix model analysis, but relatively little attention has been paid to how data are collected. 2. In most demographic population viability studies, data are sampled in permanent plots, often resulting in poor representation of some stages. It has been suggested that by using previous knowledge of species’ demography it is possible to sample demographic data more efficiently. Here we propose an alternative method that is much simpler and does not rely on any assumptions, namely sampling an equal number of individuals per stage. 3. By using demographic data from 32 species we showed that sampling an equal number of individuals per stage provides more precise estimates of both population growth rate and elasticity than the traditional plot-based method. In some cases it is also better than the estimates gained using the method based on previous knowledge of the species’ demography. The conclusions of the latter method are very sensitive to the quality of the previous knowledge of the species’ demography. In contrast, collecting demographic data from an equal number of individuals per stage is independent of any assumptions. 4. Synthesis and applications . A central aim for management of threatened species is to develop robust and accurate methods for assessing population viability that are also efficient in terms of costs and labour. A key issue is how to collect the data on which viability assessments are based. We show that it is possible to increase considerably the accuracy and robustness of demographic PVA without increasing sampling effort, by using a simple method based on sampling an equal number of individuals per life-cycle stage. Improved PVA model performance will be important to guide conservation efforts and to evaluate different management options.

Among population variation in specialist and generalist seed predation - the importance of host plant distribution, alternative hosts and environmental variation

The effect of habitat destruction on the likelihood of species survival is often estimated based on the assumption that colonization and extinctions are in balance. This assumption is not sustainable in species where the dynamics of colonization and extinctions is slow in relation to landscape changes, such as in most plants. Here we use an alternative approach, a realistic, dynamic landscape-level model that does not rely on this assumption. It enables estimation of the effect of habitat destruction using field data on the biology of a species and on real landscape structure. Because our approach relies on direct comparisons of changes in population size and survival probability due to habitat changes, it can be easily extended to other conservation questions, such as assessing the effects of events causing the extinction of populations but allowing for re- colonization, or identifying optimal reintroduction strategies. We applied this method to a perennial herb, Succisa pratensis, that is a typical grassland species. We combined detailed demographic data with information on the spatial distribution of suitable habitats to model species dynamics in the landscape under different scenarios. The results show that habitat destruction alone has little effect on regional survival. How- ever, the effect of habitat destruction increases when combined with factors causing ex- tinctions of the existing populations that are expected to play a significant role in the study system. Our results further show that an optimal reintroduction strategy at the landscape level depends on the number of available seeds. The approach presented here was designed for studying systems where species colo- nization-extinction dynamics is slow compared with landscape changes. Such time lags and nonequilibrium dynamics have been suggested to be important features of many eco- systems and life forms, and this approach is thus likely to be useful for a wide range of future studies. The approach also allows the estimation of short-term effects of habitat destruction, i.e., situations that are nonequilibrium by definition. This is never possible with equilibrium models, giving the model a wide applicability for all types of organisms.

Metapopulation dynamics have received much attention in population bi- ology and conservation. Most studies have dealt with species whose population turnover rate is much higher than the rate of patch turnover. Models of the dynamics in such systems have assumed a static patch landscape. The dynamics of many species, however, are likely to be significantly affected by the dynamics of their patches. We tested the relative im- portance of local conditions, connectivity, and dynamics of host tree patches on the meta- population dynamics of a red-listed epiphytic moss, Neckera pennata, in Sweden. Repeated surveys of the species and its host trees were conducted at three sites over a period of six years. There was a positive effect of connectivity, and colonizations mainly occurred in the vicinity of occupied trees. Colonizations were also less likely on strongly leaning trees. Local extinctions sometimes occurred from small trees with low local abundances but were most often caused by treefall. Simulations of the future (100 years) dynamics of the system showed that the metapopulation size will be overestimated unless the increased local ex- tinction rate imposed by the dynamics of the trees is accounted for. The simulations also suggested that local extinctions from standing trees may be disregarded in dynamic models for this species. This implies that the dynamics of N. pennata can be characterized as a patch-tracking metapopulation, where local extinctions are caused by patch destruction.

Metapopulation theory (summarized by Hanski 1999) is one of the most influential developments in ecology of recent decades, for example as a cornerstone of conservation biology, and as a theoretical basis for studies of dispersal and of the distribution and abundance of species. A synthesis of metapopulation theory and landscape ecology has been regarded as a key to analyses of the ecological consequences of ongoing landscape changes (Wiens 1997). Although successfully applied to many regional systems of animal populations, the usefulness of metapopulation theory for studies of plants is still open to debate. As Husband & Barrett (1996) and Eriksson (1996) concluded, rather few studies have documented metapopulations in plants, and the same holds for other forms of regional dynamics, e.g. source-sink populations and remnant populations. In a recent paper, Freckleton & Watkinson (2002) have critically reviewed studies of plant metapopulations, with the objectives of assessing whether regional populations of plants really are metapopulations, and suggesting a new typology for different forms of plant regional dynamics. Freckleton & Watkinson stress, and we agree, that these issues are not merely semantic. The concepts of regional dynamics not only determine the ways in which empirical studies are performed, but also influence the interpretation of data (illustrated by Freckleton & Watkinson with studies claiming, but not showing, the existence of metapopulations) and the modelling of spatial dynamics of plant populations. Freckleton & Watkinson (2002) begin by listing four criteria that must be fulfilled in order to regard a regional population as a metapopulation: (i) suitable habitat occurs as discrete patches that may be occupied or unoccupied; (ii) all local populations have a measurable extinction risk; (iii) habitat patches are interconnected by dispersal, allowing the possibility of re-colonization; and (iv) local populations are not completely synchronized in their dynamics. If these criteria are met, regional dynamics cannot be inferred from local processes, and local dynamics cannot be understood without referring to regional patterns or processes. Freckleton & Watkinson (2002) conclude that, given these criteria, very few cases exist where plant metapopulations have been documented. Indeed, there are a number of reasons why plants may not develop metapopulations in the same way as short-lived mobile animals. The existence of long-lived life cycle stages (e.g. seeds or vegetative ramets) means that a local population may persist for a long time even though the patch has become unsuitable. Successful dispersal and recruitment may be very sporadic, and therefore recolonization is unlikely after local population extinction. Dispersal over long distances may be governed by chance events. The definition of 'long distance' may differ between species, but in many cases it may be no more than a few hundred metres (Cain et al. 2000). Suitable habitat is difficult to define, and suitability is likely to be a continuous function of abiotic and biotic environmental factors. Freckleton & Watkinson propose that, using a metapopulation concept for describing regional populations, many plant regional populations would be described as non-equilibrium metapopulations, a conclusion we also reached for plants in fragmented habitats (Eriksson & Ehrl~n 2001). We agree with Freckleton & Watkinson (2002) that it is difficult to assess whether plants in general fulfil the criteria for metapopulations. However, we disagree with their suggestions on a new typology for regional dynamics. We also believe that their conclusions concerning the difficulties in documenting metapopulations in plants may be interpreted as indicating that local processes are sufficient for understanding regional patterns of plant populations, although we acknowledge that this may not have been their intention. We have three objectives here: (i) to comment on the typology of regional dynamics suggested by Freckleton & Watkinson (2002); (ii) to suggest how regional processes might be of importance to plant distributions irrespective of whether plants have metapopulations; and (iii) to argue that metapopulation theory should be developed further as a tool for studies of plants, rather than being replaced by other concepts.

Human population growth and resource use, mediated by changes in climate, land use, and water use, increasingly impact biodiversity and ecosystem services provision. However, impacts of these drivers on biodiversity and ecosystem services are rarely analyzed simultaneously and remain largely unknown. An emerging question is how science can improve the understanding of change in biodiversity and ecosystem service delivery and of potential feedback mechanisms of adaptive governance. We analyzed past and future change in drivers in south-central Sweden. We used the analysis to identify main research challenges and outline important research tasks. Since the 19th century, our study area has experienced substantial and interlinked changes; a 1.6°C temperature increase, rapid population growth, urbanization, and massive changes in land use and water use. Considerable future changes are also projected until the mid-21st century. However, little is known about the impacts on biodiversity and ecosystem services so far, and this in turn hampers future projections of such effects. Therefore, we urge scientists to explore interdisciplinary approaches designed to investigate change in multiple drivers, underlying mechanisms, and interactions over time, including assessment and analysis of matching-scale data from several disciplines. Such a perspective is needed for science to contribute to adaptive governance by constantly improving the understanding of linked change complexities and their impacts.

Linking spatial variation in environmental factors to variation in demographic rates is essential for a mechanistic understanding of the dynamics of populations. However, we still know relatively little about such links, partly because feedbacks via intraspecific density make them difficult to observe in natural populations. We conducted a detailed field study and investigated simultaneous effects of environmental factors and the intraspecific density of individuals on the demography of the herb Lathyrus vernus. In regression models of vital rates we identified effects associated with spring shade on survival and growth, while density was negatively correlated with these vital rates. Density was also negatively correlated with average individual size in the study plots, which is consistent with self-thinning. In addition, average plant sizes were larger than predicted by density in plots that were less shaded by the tree canopy, indicating an environmentally determined carrying capacity. A size-structured integral projection model based on the vital rate regressions revealed that the identified effects of shade and density were strong enough to produce differences in stable population sizes similar to those observed in the field. The results illustrate how the local environment can determine dynamics of populations and that intraspecific density may have to be more carefully considered in studies of plant demography and population viability analyses of threatened species. We conclude that demographic approaches incorporating information about both density and key environmental factors are powerful tools for understanding the processes that interact to determine population dynamics and abundances.

Historical events have been used to explain a wide range of phenomena including geographical distributions of species, community diversity, and population struc- ture. At the level of individuals, historical effects in which past conditions influence future performance are particularly likely to occur in long-lived organisms that store resources between seasons and that form organs months or years before their elaboration. Such carry- over mechanisms have been documented in several perennial plant species, but the impli- cations for population processes are poorly known. In this study, I examine how the history of individuals influences their future performance, population dynamics, and life cycle, structure in the long-lived herb Lathyrus vernus. Overall effects of plant history on pop- ulation dynamics, in terms of growth rate, reproductive values, stable stage distribution, and elasticities, are examined by comparing an ordinary first-order matrix model with a second-order matrix model. In the latter, not only the present state of individuals, but also their past state is allowed to influence future fate. The results demonstrate that the history of individuals is sometimes important in models of population dynamics. Plant size change over a one-year period was negatively correlated among time intervals. Addition of the previous year's stage in population models shifted the growth rate from positive (X = 1.010) to negative (X = 0.986) and increased the proportion of small established individuals in the stable stage distribution. If historical effects are due to a capacity to buffer environmental variation and regain size or state, as in L. vernus, then recruitment contributes less and stasis more to population growth than suggested by ahistorical models. The presence of historical effects at the level of individuals, in any form, may have important consequences for population development and should be included in any interpretation of the life-cycle structure.

Anthropogenic changes in landscape structure, such as habitat loss, habitat subdivision and edge increase, can strongly affect the performance of plants, leading to population declines and extinctions. Many studies to date have focused on single characteristics of landscape structure or single life-cycle phases, but they poorly discern the different pathways through which landscape change influences plant population dynamics via different vital rates. In this study, we evaluated the effect of two structural characteristics (habitat quantity and edge length) on vital rates and population growth rates of a perennial forest plant (Primula vulgaris) in a historically managed landscape. Areas with higher amounts of forest habitat had higher population growth rates due to higher recruitment, survival and growth of seedlings, while increased forest edge length was positively associated with population growth rates primarily due to a higher survival of reproductive individuals. Effects were stronger during the first of the two transition intervals studied. The results demonstrate that changes in different landscape structural characteristics may result in opposing effects acting via different vital rates, and highlight the need for integrative analyses to evaluate the effects of rapid landscape transformation on the current and long term plant population dynamics. © 2013 The Authors., We thank J. Rodríguez, D. Martínez, V. Rivera, J. Rodríguez-Pérez, E. Vigón and I. Peñacoba for their help in field and lab work. We acknowledge funding from a FPU grant (MICINN-European Social Fund) to AV and the projects CGL2008-1275/BOS (MICINN) and IB08-039 (PCTI-FICYT) to DG, and CGL2010-21642 to MBG.

Abandonment of traditional land-use practices can have strong effects on the abundance of species occurring in agricultural landscapes. However, the precise mechanisms by which individual performance and population dynamics are affected are still poorly understood. To assess how abandonment affects population dynamics of Succisa pratensis we used data from a 4-year field study in both abandoned and traditionally grazed areas in moist and mesic habitats to parameterize integral projection models. Abandoned populations had a lower long-term stochastic population growth rate (λ S = 0.90) than traditionally managed populations (λ S = 1.08), while λ S did not differ between habitat types. The effect of abandonment differed significantly between years and had opposed effects on different vital rates. Individuals in abandoned populations experienced higher mortality rates and lower seedling establishment, but had higher growth rates and produced more flower heads per plant. Population viability analyses, based on a population survey of the whole study area in combination with our demographic models, showed that 32 % of the populations face a high risk of extinction (>80 %) within 20 years. These results suggest that immediate changes in management are needed to avoid extinctions and further declines in population sizes. Stochastic elasticity analyses and stochastic life table response experiments indicated that management strategies would be most effective if they increase survival of small plants as well as seedling establishment, while maintaining a high seed production. This may be achieved by varying the grazing intensity between years or excluding grazers when plants are flowering. ispartof: Population Ecology vol:56 issue:1 pages:151-160 status: published

10 páginas, 3 figuras, 2 tablas, Peripheral populations have long been predicted to show lower vital rates, higher demographic fl uctuations, and lower densities than central populations. However, recent research has questioned the existence of clear patterns across species ’ ranges. To test these hypotheses, we monitored fi ve central and six northern peripheral populations of the widespread herb Plantago coronopus along the European Atlantic coast during 5 yr. We estimated population density, and calculated mean values and temporal variability of four vital rates (survival, individual growth, fecundity and recruitment) in hundreds of plants in permanent plots. Central populations showed higher fecundity, whereas peripheral populations had higher recruitment per reproductive plant, indicating a higher overall reproductive success in the periphery. Central populations showed a marginally signifi cant tendency for higher growth, and there were no diff erences between range positions in survival. Fecundity and growth were aff ected by intraspecifi c competition, and recruitment was aff ected by precipitation, highlighting the importance of local environmental conditions for population performance. Central and peripheral populations showed no signifi cant diff erences in temporal variability of vital rates. Finally, density was signifi cantly higher in peripheral than in central populations, in discrepancy with the abundant-centre model. Density was correlated to seedling recruitment, which would counterbalance in peripheral populations the lower fecundity and the tendency for lower growth of established plants. Such compensations among vital rates might be particularly common in widespread plants, and advise against simplistic assumptions of population performance across ranges. Th e whole species ’ life cycle should be considered, since diff erent arrangements of vital rates are expected to maximize fi tness in local environments. Our results show also the importance of discerning between geographical periphery and ecological marginality. In a context of climate-induced range shifts, these considerations are crucial for the reliability of nichemodels and the management of plant peripheral populations., Th is study was funded by the Spanish Ministry of Science and Innovation by means of two National Projects (CGL2006-08507; CGL2010-21642) to MBG and FPU scholarships to JV and RB. We thank W. F. Morris and D. Doak for helpful comments on the manuscript. We are indebted to M. P. Errea for her guidance in the analysis of Voronoi polygons, to M. Maestro for soil analyses and to A. Adsuar, A. Barcos, R. Castillo, R. Corri à , R. Forrest, A. de Frutos, E. L ó pez, J. Mart í nez, E. Mor á n, C. Niklasson, F. Ojeda, S. Palacio, I. Pardo, A. P é rez, C. P é rez, P. S á nchez, A. Taboada, M. Talavera and A. Vale for their valuable help in fi eld and laboratory work through years.

Climate change is expected to influence the viability of populations both directly and indirectly, via species interactions. The effects of large-scale climate change are also likely to interact with local habitat conditions. Management actions designed to preserve threatened species therefore need to adapt both to the prevailing climate and local conditions. Yet, few studies have separated the direct and indirect effects of climatic variables on the viability of local populations and discussed the implications for optimal management. We used 30 years of demographic data to estimate the simultaneous effects of management practice and among-year variation in four climatic variables on individual survival, growth and fecundity in one coastal and one inland population of the perennial orchid Dactylorhiza lapponica in Norway. Current management, mowing, is expected to reduce competitive interactions. Statistical models of how climate and management practice influenced vital rates were incorporated into matrix population models to quantify effects on population growth rate. Effects of climate differed between mown and control plots in both populations. In particular, population growth rate increased more strongly with summer temperature in mown plots than in control plots. Population growth rate declined with spring temperature in the inland population, and with precipitation in the coastal population, and the decline was stronger in control plots in both populations. These results illustrate that both direct and indirect effects of climate change are important for population viability and that net effects depend both on local abiotic conditions and on biotic conditions in terms of management practice and intensity of competition. The results also show that effects of management practices influencing competitive interactions can strongly depend on climatic factors. We conclude that interactions between climate and management should be considered to reliably predict future population viability and optimize conservation actions.

Extinction debts can result from many types of habitat changes involving mechanisms other than metapopulation processes. This is a fact that most recent literature on extinction debts pays little attention to. We argue that extinction debts can arise because (i) individuals survive in resistant life-cycle stages long after habitat quality change, (ii) stochastic extinctions of populations that have become small are not immediate, and (iii) metapopulations survive long after that connectivity has decreased if colonization–extinction dynamics is slow. A failure to distinguish between these different mechanisms and to simultaneously consider both the size of the extinction debt and the relaxation time hampers our understanding of how extinction debts arise and our ability to prevent ultimate extinctions.

We experimentally investigated how pollinator- and herbivore-induced changes influence the performance of the long-lived herb Primula veris. Eight treatments that corresponded to natural factors normally affecting this species were designed to enhance or reduce reproductive success and resource availability (flower removal, supplementary pollination, defoliation). During the experimental season and in the following year we quantified responses in terms of survival, growth, and seed production of reproductive plants. Matrix population models were used to calculate population growth rate using the demographic parameters recorded in permanent plots and respective treatment groups. Seed production was not limited by pollen availability, and we found no evidence of a cost of reproduction. Leaf removal had either no effect or a negative effect on future performance, depending on the timing of removal. Defoliation early in the season reduced current seed production and future growth, whereas removal during fruit development affected performance in the following year. Demographic models suggest that leaf damage has a smaller negative impact than flower removal on overall performance in this population. Our results suggest that the source-sink paths vary over the season and that the timing of herbivory may influence the extent to which effects are carried over to subsequent reproductive seasons.

Spatio-temporal variation in seed predation may strongly influence both plant population dynamics and selection on plant traits. The intensity of seed predation may depend on a number of factors, but the relative importance of previous predator abundance (“local legacy”), spatial distribution of the host plant, environmental factors and plant characteristics has been explored in few species. We monitored seed predation in the perennial herb Primula farinosa, which is dimorphic for scape length, during 5 consecutive years, in a 10-km × 4-km area comprising 79 P. farinosa populations. A transplant experiment showed that the seed predator, the oligophagous tortricid moth Falseuncaria ruficiliana, was not dispersal limited at the spatial scale corresponding to typical distances between P. farinosa populations. Correlations between population characteristics and incidence and intensity of seed predation varied among years. The incidence of the seed predator was positively correlated with host population size and mean number of flowers, while intensity of seed predation in occupied patches was positively related to the frequency of the long-scaped morph in 2 years and negatively related to host population size in 1 year. In both scape morphs, predation tended to increase with increasing frequency of the long morph. There was no evidence of a local legacy; incidence and intensity of seed predation were not related to the abundance of the seed predator in the population in the previous year. Taken together, the results indicate that among-population variation in seed predation intensity is determined largely by patch selection and that the seed predator’s preference for tall and many-flowered inflorescences may not only affect selection on plant traits within host plant populations, but also the overall intensity of seed predation.

11 páginas, 3 figuras, 3 tablas, 1 dibujo.-- et al., [EN]: Although the effects of deterministic factors on population viability often are more important than stochasticity, few researchers have dealt with the effect of deterministic habitat changes on plant population demography. We assessed population viability for the perennial herb Primula veris L. and identified targets for management based on demographic data from five different habitat types representing different degrees of canopy closure. We conducted replicate studies at the border of the distribution area and in more central parts. Demographic patterns were similar between the two regions. Most study populations had a positive population growth, and only populations in late phases of forest succession showed consistently negative trends. The populations of open habitats had high seedling recruitment, and the populations of early and middle forest succession had high seed production. The importance of survival for population growth rate increased with increasing habitat closure, whereas the importance of growth and reproduction decreased. Results of the elasticity analysis suggested that the best method to manage decreasing late-successional populations is to increase survival of the largest individuals. The life-table response experiment (LTRE) analysis, however, showed that survival of the largest individuals contributed little to differences in population growth rates of different habitats, whereas seed production and growth of small individuals were more important. Moreover, direct perturbation of the performance of the largest stages showed that late-successional populations would not attain positive population growth even if the largest stages had no mortality at all. We conclude that restoration of recruitment is the only possibility for positive population growth in late-successional populations of P. veris, although the elasticities of recruitment transitions are low. Our results also suggest that retrospective demographic methods such as LTRE constitute an important and necessary complement to prospective methods such as elasticities in identifying management targets., [ES]: Aunque los efectos de factores determinísticos sobre la viabilidad poblacional a menudo son más importantes que la estocasticidad, pocos investigadores han abordado el efecto de los cambios determinísticos del hábitat sobre la demografía de poblaciones de plantas. Evaluamos la viabilidad poblacional de la hierba perenne Primula veris L. e identificamos objetivos para su gestión con base en datos demográficos obtenidos en cinco tipos de hábitat diferentes que representan diferentes grados de oclusión del dosel. Realizamos estudios replicados en el límite del área de distribución y en áreas más centrales. Los patrones demográficos eran similares en las dos regiones. La mayoría de las poblaciones estudiadas tenían un crecimiento poblacional positivo, y solo mostraron tendencias consistentemente negativas las poblaciones en fases avanzadas de sucesión del bosque. Las poblaciones en hábitats abiertos tenían alto reclutamiento de plántulas, y las poblaciones en bosques en sucesión temprana y media tenían alta producción de semillas. La importancia de la supervivencia para la tasa de crecimiento poblacional aumentó con el incremento de la oclusión del hábitat, mientras que disminuyó la importancia del crecimiento y la reproducción. Los resultados del análisis de elasticidad sugieren que el mejor método para manejar poblaciones decrecientes de etapas tardías de sucesión es el incremento de la supervivencia de los individuos más grandes. Sin embargo, el análisis de experimento de respuesta de tabla de vida (ERTV) mostró que la supervivencia de los individuos más grandes contribuyó poco a las diferencias en las tasas de crecimiento poblacional en hábitats diferentes, mientras que la producción de semillas y el crecimiento de individuos pequeños fueron más importantes. Más aun, la perturbación directa del funcionamiento de las etapas mayores mostró que las poblaciones de sucesión tardía no llegarían a tener crecimiento poblacional positivo aun si no hubiera mortalidad en las etapas mayores. Concluimos que la restauración del reclutamiento es la única posibilidad de crecimiento poblacional en poblaciones de P. veris de sucesión tardía, aunque las elasticidades de las transiciones de reclutamiento sean bajas. Nuestros resultados también sugieren que los métodos demográficos retrospectivos, como ERTV, constituyen un complemento necesario e importante de los métodos prospectivos, como las elasticidades, en la identificación de objetivos de conservación., The study was financed by World Wide Fund of Sweden, the Swedish Research Council (to K.L. and J.E), the Swedish Research Council for Environment, Agricultural Sciences and Spatial Planning (FORMAS) (to J.E.), Östersjöstiftelsen (to K.L.), and a postdoctoral grant from the Spanish Ministerio de Educación y Ciencia MEC (to M.B.G; ref. EX94 17713636).

Plants have two principal defense mechanisms to decrease fitness losses to herbivory: tolerance, the ability to compensate fitness after damage, and resistance, the ability to avoid damage. Variation in intensity of herbivory among populations should result in variation in plant defense levels if tolerance and resistance are associated with costs. Yet little is known about how levels of tolerance are related to resistance and attack intensity in the field, and about the costs of tolerance. In this study, we used information about tolerance and resistance against larval herbivory by the butterfly Anthocharis cardamines under controlled conditions together with information about damage in the field for a large set of populations of the perennial plant Cardamine pratensis. Plant tolerance was estimated in a common garden experiment where plants were subjected to a combination of larval herbivory and clipping. We found no evidence of that the proportion of damage that was caused by larval feeding vs. clipping influenced plant responses. Damage treatments had a negative effect on the three measured fitness components and also resulted in an earlier flowering in the year after the attack. Tolerance was related to attack intensity in the population of origin, i.e. plants from populations with higher attack intensity were more likely to flower in the year following damage. However, we found no evidence of a relationship between tolerance and resistance. These results indicate that herbivory drives the evolution for increased tolerance, and that changes in tolerance are not linked to changes in resistance. We suggest that the simultaneous study of tolerance, attack intensity in the field and resistance constitutes a powerful tool to understand how plant strategies to avoid negative effects of herbivore damage evolve.