ABSTRACT Ecological data are increasingly collected by networks of collaborators using replicated designs and methods, which can significantly improve the quality and quantity of data throughout the ecological niche and geographic range of species or communities. The coordinated generation and management of data is critical for producing datasets (Standard Data Products) across multiple sites that can be used by different researchers, over extended time periods and for multiple purposes. We describe and use a Quality Assurance framework for the design, collection and production of reproducible Standard Data Products for distributed ecology projects. We identified six critical project elements of a Quality Assurance framework (QA1‐6) to produce ecological Standard Data Products with high immediate and future value. We applied the Quality Assurance framework to the Plantpopnet project as a case‐study. Plantpopnet is a coordinated distributed system for population macroecology using the model species Plantago lanceolata. We mapped Plantpopnet activities to the Quality Assurance Framework as follows: (QA1) Measurable objectives: research project objectives with data requirements, (QA2) Process control: governance policies, (QA3) Project specific procedures: model organism selection and data collection protocol, (QA4) Supporting production of high quality data: recruitment, retention and engagement of participants, (QA5) Data management: data management plan and reproducible data cleaning workflow, (QA6) Production and management of outputs: Standard Data Products and papers. Explicit use of Quality Assurance, project and data management tools together with standardised ecological methods facilitated the design, collection, maintenance and sustainability of high‐quality data products. We provide a Quality Assurance framework together with governance documents, code and data for a reproducible Standard Data Product. This framework supports a distributed funding model which can be sustainably applied to facilitate future research and applications of coordinated distributed ecology projects.

Background and Aims Climate influences species performance and distribution both directly, through physiological constraints, and indirectly, by modulating biotic interactions. However, the relative importance of these pathways remains poorly understood, limiting our ability to predict species responses to environmental change. Here, we investigated how microclimate influences the growth of a cold-adapted lichen both directly and indirectly, through effects on mollusc grazing, and whether these effects differ among populations of different origins.Methods We conducted a transplant experiment using lobes of Peltigera aphthosa collected from five geographically distant populations along a 1200-km latitudinal gradient in Sweden. The lobes were transplanted to 56 forest sites spanning a broad microclimatic gradient near the species' warm-range margin in Sweden, and we monitored their growth and grazing damage for one year. Using piecewise structural equation models, we quantified the direct and indirect effects of microclimate through grazing on lichen growth and assessed whether these effects differed among source populations.Key Results We found no evidence for direct effects of microclimate on lichen growth. Instead, microclimate indirectly influenced growth through mollusc grazing. Grazing damage increased with warmer temperatures (more growing degree days) and higher air humidity (lower vapour pressure deficit) during the growing season and grazing reduced lichen growth. While population origin did not affect direct responses to microclimate, populations differed in their susceptibility to grazing.Conclusions Our study highlights the importance of indirect microclimatic effects mediated by biotic interactions in shaping species performance near its warm-range margin. The absence of direct microclimatic effects, combined with intraspecific variation in susceptibility to grazing, underscores the need to consider both biotic interactions and differences among populations when predicting species responses to climate change. Transplant experiments across microclimatic gradients offer a valuable method to gain insights into the complex interplay between local adaptation and abiotic and biotic factors of species performance.

The occurrence patterns of invasive species are shaped, on the one hand, by the availability of suitable habitat, and, on the other hand, by how dispersal has progressed since their introduction to the new region. This complicates attempts to understand and predict their distributions, especially if the relative importance of these factors differs between spatial scales. Here, we investigate environmental and dispersal-linked patterns in the distribution of the globally invasive plant Lupinus polyphyllus. For this purpose, we created a uniquely extensive and high-resolution occurrence dataset for the entire country of Sweden by surveying 2100 km of roadside, collected density and size data from 152 populations, and analyzed global distribution patterns using citizen science data. Analyses revealed that at the regional scale (>50 km), lupine occurrence was best explained by climate, with some effects of soil chemistry. However, at smaller scales, both lupine presence and density were best explained by the presence of nearby buildings, suggesting a large role of human-aided dispersal. Furthermore, the results depended on road type: environmental variation (especially soil chemistry) only weakly limited lupine occurrence along highways, suggesting that large roads may act as dispersal corridors across otherwise unsuitable habitat. When integrating modeling results for Sweden with observations from the global range of L. polyphyllus, further northward expansion in Scandinavia appears possible even under the current climate regime, but likely with limited maximum abundance in northern regions. Our results illustrate how a nested study design and a combination of data sources enable a more comprehensive assessment of the factors influencing a biological invasion.

The control of invasive plants can be costly and labor-intensive. Mowing provides a simple and tractable control option in many settings, but its efficacy depends on when the mowing occurs in relation to the target species' life cycle. Here we present the results of a multi-year field experiment, replicated over 25 sites across Sweden, testing the effects of different mowing regimes on the invasive large-leaved lupine, Lupinus polyphyllus. Early-season mowing (during the flowering stage) had stronger effects than late-season mowing (during the fruiting stage), but combining both mowing periods was more effective than either on its own. Mowing reduced the number as well as the size of lupine shoots, and especially depressed the rate at which lupine populations flowered, which may help reduce population spread. Demographic modeling indicated that continued twiceyearly mowing would lead to suppressed or reversed population growth at all sites. However, results were strongly dependent on habitat, with strong population reduction in woodlands, weaker effects in roadside environments, and intermediate results in grasslands. The lack of a latitudinal pattern suggests that twice-yearly mowing may be a useful control method for L. polyphyllus across its invasive range, although success is likely to depend on habitat type. More broadly, our results underscore that the within-season timing and frequency of weed control treatments can both greatly affect the outcome.

Identifying environmental factors associated with local adaptation and traits under selection is key to linking evolutionary processes to the environment. While reciprocal transplantation studies and provenance experiments often have demonstrated adaptation at relatively large spatial scales, adaptation can also occur at very small spatial scales. Combining a crossing experiment with field transplantations, we investigated whether Cerastium fontanum has adapted to geothermally induced small-scale soil temperature differences. Offspring representing a wide range of parental soil temperatures were transplanted across the same temperature range, and traits and fitness components were measured over 2 yr. We evaluated the relationship between plant performance and soil temperatures, the degree of adaptation to their source thermal environment, and the dependence of adaptation on flowering time. Survival, flowering incidence, and overall fitness were lower in warmer soils. However, adaptation to temperature was asymmetric; while all plants performed well at colder sites, individuals from colder origins performed poorly at warmer sites. Flowering time and fitness varied in relation to soil temperature, as well as the difference between planting and source thermal environments. Our findings indicate that small-scale variation in soil temperature underlies fine-scale adaptation and provides important knowledge to understand evolutionary effects of microclimatic variation.

Genetic differentiation in traits is assumed to frequently occur in response to divergent natural selection. For example, developmental traits might respond to differences in climate. However, little is known about when and at which spatial scales environmental differences lead to genetic differentiation, and to what extent there is genetic differentiation also in trait plasticity. Using a crossing design and a greenhouse heating experiment, we investigated genetic differentiation in thermal sensitivity of flowering time in a perennial herb along small-scale gradients in geothermal soil heating in Iceland. We found additive genetic variation in both flowering time and thermal plasticity of flowering time. Genetic differentiation in the median flowering date of individuals showed a counter-gradient pattern; flowering being earlier at higher greenhouse temperatures, while at a given temperature individuals originating from warmer soils flowered later than individuals from colder soils. We found no corresponding pattern for plasticity, suggesting that genetic differentiation in phenology in response to soil heating has occurred through changes in trait means rather than in plasticity. Findings such as these identifying genetic trait differentiation along an environmental gradient are key to understand how environmental variation can drive the process of local adaptation, and to predict responses to future environmental changes.

Individual plant size often determines the vital rates of growth, survival and reproduction. However, size can be measured in several ways (e.g. height, biomass, leaf length). There is no consensus on the best size metric for modelling vital rates in plants. Demographic datasets are expanding in geographic extent, leading to choices about how to represent size for the same species in multiple ecological contexts. If the choice of size variable varies among locations, inter-population comparative demography increases in complexity. Here, we present a framework to perform size metric selection in large-scale demographic studies. We highlight potential pitfalls and suggest methods applicable to diverse study organisms. We assessed the performance of five different size metrics for the perennial herb Plantago lanceolata, across 55 populations on three continents within its native and non-native ranges, using the spatially replicated demographic dataset PlantPopNet. We compared the performance of each candidate size metric for four vital rates (growth, survival, flowering probability and reproductive output) using generalized linear mixed models. We ranked the candidate size metrics based on their overall performance (highest generalized R2) and homogeneity of performance across populations (lowest total magnitude of, and variance in, population-level error). While all size variables performed well for modelling vital rates, the number of leaves (modelled as a discrete variable, without transformation) was selected as the best size metric, followed by leaf length. We show how to interrogate potential trade-offs between overall explanatory power and homogeneity of predictions across populations in any organism. Synthesis. Size is an important determinant of vital rates. Using a dataset of unprecedented spatial extent, we find (a) consistent size-based models of growth, survival and reproduction across native and non-native populations of this cosmopolitan plant species and (b) that several tested size metrics perform similarly well. This is encouraging for large-scale demographic studies and for comparative projects using different size metrics, as they may be robust to this methodological difference.

All populations are affected by multiple environmental drivers, including climatic drivers such as temperature or precipitation and biotic drivers such as herbivory or mutualisms. The relative response of a population to each driver is critical to prioritizing threat mitigation for conservation and to understanding whether climatic or biotic drivers most strongly affect fitness. However, the importance of different drivers can vary dramatically across species and across populations of the same species. Theory suggests that the response to climatic versus biotic drivers can be affected by both the species' fundamental niche breadth and the latitude of the population at which the response is measured. However, we have few tests of how these two factors affect relative response to drivers separately, let alone tests of how niche breadth and latitude together influence responses. Here, we use a meta-analysis of published studies on population response to climatic and biotic drivers in terrestrial plants, combined with estimates of climatic niche breadth and position within climatic niche derived from herbarium records, to show that species' niche breadth is the primary determinant of response to climatic versus biotic drivers. Namely, we find that response to climatic drivers changes only minimally with increasing niche breadth, while response to biotic drivers increases with niche breadth. We see similar relationships when considering range size instead of niche breadth. Surprisingly, we find no effects of latitude on the relative effect of climatic versus biotic drivers. Our work suggests that populations of species with small and large ranges experience similar extirpation risks due to the negative impacts of climate change. By contrast, populations of species with large (but not small) ranges may be highly susceptible to changes in densities or distributions of interacting species.

A common approach to investigating species' niches is to examine relationships between spatial variation in environmental conditions and contemporary species occurrences, using species distribution models (SDM or niche models). The relationships between past species distributions and environmental variation over time are less commonly explored. One way to examine effects on species changes over time is to use paleo-datasets to parameterize niche models, where the use of temporal variation allows for making more direct links between past species and environmental conditions through records of past changes. We examined the impact of five environmental variables (temperature, incidence of external nutrient input, local [within bog] moisture, incidence of regionally dry periods, and fire activity) on temporal variation in peatland species composition, occurrences, and abundances (Sphagnum, Eriophorum, Carex, and Ericaceous dwarf shrubs) using a high-resolution peat macrofossil paleo-record spanning the last ~10,000 years from the Store Mosse bog (south-central Sweden). Our results showed that species composition was affected by external nutrient input, local moisture conditions and incidence of regionally dry conditions. The presence and abundance of different species groups were mainly affected by external nutrient input and the incidence of regionally dry periods. Moreover, hummock Sphagna benefited from external nutrient input and low moisture, and in one species, warmer temperatures. Intermediate Sphagna from cooler temperatures with no external nutrient input, and hollow Sphagna from cooler temperatures and external nutrient input. Lastly, our results showed that environmental effects differed between the successional stages of the peatland in one case. Overall, the observed species' responses imply that peatland carbon dynamics will shift with future changes in climate. By examining links between climate and species responses of the past, this study demonstrates that the paleo-data approach in SDMs can contribute to a better understanding of the environmental effects influencing species distributions on longer time scales, thereby providing a valuable tool to improve predictions of future climate change effects.

Due to climate change, droughts are increasingly frequent and intense. Yet, their impact on boreal forest fungal communities remains unclear, especially across different fungal functional and taxonomic groups. We induced an experimental rainfall exclusion for 45 summer days, using a paired design of 1 x 1 m treatment and control plots replicated in 25 sites in a boreal forest landscape in Sweden. Immediately after the experiment, we assessed the effects on soil fungal biomass, community composition and, after 2 months, sporocarp production. We did not detect significant effects of the rainfall exclusion on soil fungal biomass, but the fungal community composition was affected. In the rainfall exclusion plots, richness of ectomycorrhizal species with extensive extramatrical mycelia and saprotrophic basidiomycetes was reduced, while richness of ascomycetes was not affected. Sporocarp production of both saprotrophic and ectomycorrhizal fungi was reduced. The clear effects of a small-scale rainfall exclusion demonstrated in our study suggest that belowground fungal communities in boreal forests may be vulnerable to drought.

All plants are influenced by the temperatures they are exposed to and fascinating adaptations to extreme temperatures have been described for many of them. However, the extent to which adaptation to thermal extremes is associated with costs, in terms of reduced performance at less or other stressful temperatures, is poorly known, especially for plants. In Iceland, there are two lineages of Agrostis stolonifera, one that occurs exclusively on geothermally heated soils (> 50 °C) and one that is only found on non-thermal soils. Since Iceland is a subarctic island, non-thermal areas surrounding the geothermal areas can get bitterly cold. This stark contrast in temperatures over short geographic distances provides an excellent system for studying adaptations to thermal extremes and potentially associated trade-offs. To test whether the geothermal lineage is more heat tolerant and whether this heat tolerance is associated with reduced performance under cooler conditions, we compared the heat and cold stress responses of the two lineages experimentally. No plants survived the hottest treatment (56 °C), only geothermal plants survived the second hottest treatment (49 °C) and geothermal plants also outperformed the non-thermal plants following the 46 °C treatment. In contrast, there were no differences in survival between geothermal and non-thermal plants under intermediate and cold conditions (41 °C, 21 °C and − 4 °C), but non-thermal plants outperformed geothermal plants under these conditions. These results suggest that there is a trade-off between tolerating extreme heat and performance under cooler conditions, possibly indicating that geothermal A. stolonifera represents a specialised thermophilic lineage in Iceland. Our findings provide new empirical data on whole-plant responses to different thermal conditions, further understanding of the consequences of adapting to high and low temperature extremes, and raise new questions about the mechanisms, benefits and costs of thermal specialisation under different climatic conditions.

As the climate is changing, species respond by changing their distributions and abundances. The effects of climate are not only direct, but also occur via changes in biotic interactions, such as competition. Yet, the role of competition in mediating the effects of climate is still largely unclear. To examine how climate influences species performance, directly and via competition with other species, we transplanted two moss species differing in climate niches, alone and together at 59 sites along a climate gradient. Growth was monitored over three growing seasons. In the absence of competition, both species performed better under warmer conditions. Yet, when transplanted together, a warmer climate had negative effects on the northern moss, while the effects remained positive for the southern species. The negative effect of a cold climate on the southern species was larger when both species were transplanted together. Over three growing seasons, the southern species almost outcompeted the northern in warmer climates. Our results illustrate how competitive interactions can modify, and even reverse, the direct effects of climate on organism performance. A broader implication of our results is that species interactions can have important effects on how environmental and climate change influence performance and abundance.

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Natural selection on traits expressed repeatedly by individuals is usually investigated with a focus on mean values, although within‐individual trait distributions often differ also in other aspects, such as their spread and shape. In plants producing multiple flowers during a season, there might not be a single optimal flowering time, but rather an optimal distribution of flower opening dates. This optimal distribution might depend on both resource allocation patterns and interactions with the abiotic and biotic environment. In this study, we quantified mean, variance, skewness and kurtosis of 495 individual flowering schedules (5287 flowers) over 3 years, and assessed phenotypic selection on these aspects of the within‐individual distribution of opening dates in the perennial herb Lathyrus vernus. We also explored how selection on within‐individual variation in flowering schedules was related to effects on two fitness components: fruit set and the proportion of seeds escaping pre‐dispersal predation. Within‐individual variation in phenology was larger than, or at least similar to, among‐individual variation in all years. We found phenotypic selection on several aspects of individual flowering schedules. In 1 year, selection favoured plants with higher variance in opening dates, and this coincided with a higher fruit set in plants with an increased spread of the flowering schedule. In two of the study years, selection favoured a higher asymmetry of the flowering schedule, and plants with more right‐skewed distributions had higher fruit set and higher proportions of seeds escaping predation. Both fruit set and seed predation increased with an earlier mean flowering, resulting in no net selection on mean flowering date. Synthesis: Our results suggest that phenotypic selection on the spread and shape of flower opening date distributions might be at least as important as selection on the mean flowering date. In a broad sense, this implies that we should consider the entire trait distribution if we aim to understand the evolution of traits that are expressed multiple times within individuals.

Extreme droughts are globally increasing in frequency and severity. Most research on drought in forests focuses on the response of trees, while less is known about the impacts of drought on forest understory species and how these effects are moderated by the local environment. We assessed the impacts of a 45-day experimental summer drought on the performance of six boreal forest understory plants, using a transplant experiment with rainout shelters replicated across 25 sites. We recorded growth, vitality and reproduction immediately, 2 months, and 1 year after the simulated drought, and examined how differences in ambient soil moisture and canopy cover among sites influenced the effects of drought on the performance of each species. Drought negatively affected the growth and/or vitality of all species, but the effects were stronger and more persistent in the bryophytes than in the vascular plants. The two species associated with older forests, the moss Hylocomiastrum umbratum and the orchid Goodyera repens , suffered larger effects than the more generalist species included in the experiment. The drought reduced reproductive output in the moss Hylocomium splendens in the next growing season, but increased reproduction in the graminoid Luzula pilosa . Higher ambient soil moisture reduced some negative effects of drought on vascular plants. Both denser canopy cover and higher soil moisture alleviated drought effects on bryophytes, likely through alleviating cellular damage. Our experiment shows that boreal understory species can be adversely affected by drought and that effects might be stronger for bryophytes and species associated with older forests. Our results indicate that the effects of drought can vary over small spatial scales and that forest landscapes can be actively managed to alleviate drought effects on boreal forest biodiversity. For example, by managing the tree canopy and protecting hydrological networks.

PREMISE:In plants, within-individual trait variation might result from mechanisms related to ontogenetic contingency, i.e., to the position of a particular structure within the plant, previous developmental events, and/or the developmental environment. Flower position within inflorescences as well as inflorescence position within plants can influence resource provisioning, phenology, biotic interactions, and reproductive success. Despite the potential implications of within-individual variation in plant reproductive phenotypes, its causes and effects on reproductive success are still little explored. METHODS:We assessed how reproductive success, in terms of fruit and seed set, and seed predation of 5883 flowers in Lathyrus vernus were influenced by their position within and among racemes, to what extent relationships between flower position and reproductive success and seed predation were mediated by phenology, and if positional effects on reproductive success depended on the external environment. RESULTS:In three years, basal flowers and racemes opened earlier and had higher fruit set than distal. Basal flowers also experienced higher seed predation. Differences among racemes in fruit and seed set were largely related to phenology, while differences in fruit set, seed set, and seed predation within racemes were not. In one year, differences in fruit set among flowers at different positions depended on flowering duration. CONCLUSIONS:Our results highlight the important role of ontogenetic contingency for within-individual variation in phenology and reproductive success. As the spatial distribution of reproductive structures affects both within-plant trait distributions and fitness, it is a likely target for natural selection.

Range 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 performance in marginal populations are widespread, then populations from the high-latitude margin (HLM) should perform as well as or better than central populations, whereas low-latitude margin (LLM) populations should perform worse. Global. 1995–2019. Plants and animals. To test our prediction, we used a meta-analysis to quantify empirical support for asymmetry in the performance of high- and low-latitude margin populations compared to central populations. Performance estimates (survival, reproduction, or lifetime fitness) for populations occurring in their natural environment were derived from 51 papers involving 113 margin-centre comparisons from 54 species and 705 populations from the Americas, Europe, Africa and Australia. 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 realms (marine vs terrestrial). Populations 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 realms. Differences in performance were weakly ( p  = .08) related to the difference in average temperatures between central and marginal populations. The observed asymmetry in performance in marginal populations is consistent with predictions about the effects of global climate change, though further research is needed to confirm the effect of climate. It indicates that changes in demographic rates in marginal populations can serve as early-warning signals of impending range shifts.

Photo 1. Our study site was located in the Hengill geothermal area, located 40 km east of Reykjavik, Iceland, (64°03′N; 21°18′W, ~360 m.a.s.l.), at the base of the Hengill volcanic system. The study area, comprising ~1 km2, includes the Fremstidalur (left) and Miðdalur valleys (center and right), and the main vegetation type consists of unmanaged, but grazed, subarctic grassland. There are large differences in soil temperature over distances of only a few meters (see Photo 2), but very small differences in other abiotic factors such as soil chemistry, elevation or vegetation type. Photo credit: Vigdís F. Helmutsdóttir. Photo 2. Bedrock of the Hengill geothermal area contains geothermal channels originating from high volcanic activity, which warm the water and soil through radiative heating. Geothermally heated water (left) or steam (center) reaches the surface in some places, and there is a large variation in soil temperatures across the study site, ranging from no geothermal heating to more than 20°C above ambient temperature over short distances (10–20 m), with little to no warming on the air temperature. This system has been heated for over 50 years or longer, offering a unique natural laboratory for studying the long-term effects of warming. In our study, soil temperature was measured in May each year, at 10 cm depth in the immediate vicinity (<2 cm) of each individual plant, using a digital thermometer (right). Photo credit: Vigdís F. Helmutsdóttir (left and right) and Katarina Fast Ehrlén (center). Photo 3. Our study species, Cerastium fontanum (Caryophyllaceae) is a perennial herb that is common in subarctic and arctic ecosystems. Individuals produce 1–30 stems that are 10–30 cm long, with small, hairy leaves. Each stem carries 1–6 flowers with 5–7 mm long petals. This species flowers in June and July in the study area and it is self-compatible, but can also be cross-pollinated by insects. Fruits mature from July to August, and seeds show unspecialized seed dispersal. We used data from two growing seasons to assess how flowering time, fitness, and phenotypic selection on flowering time in this species vary with soil temperature along a natural soil warming gradient in the Hengill geothermal area. We found an earlier flowering time and a lower fitness on warmer soils in both study years. In one of the 2 years, natural selection favored earlier flowering on colder soils and later flowering on warmer soils. Photo credit: Vigdís F. Helmutsdóttir (left and right) and Katarina Fast Ehrlén (center). These photographs illustrate the article “Maladaptive plastic responses of flowering time to geothermal heating” by Johan Ehrlén, Alicia Valdés, Vigdís F. Helmutsdóttir, and Bryndís Marteinsdóttir published in Ecology. https://doi.org/10.1002/ecy.4121

Forest fragmentation increases the amount of edges in the landscape. Differences in wind, radiation, and vegetation structure create edge-to-interior gradients in forest microclimate, and these gradients are likely to be more pronounced during droughts and heatwaves. Although the effects of climate extremes on edge influences have potentially strong and long-lasting impacts on forest understory biodiversity, they are not well understood and are not often considered in management and landscape planning. Here we used a novel method of retrospectively quantifying growth to assess biologically relevant edge influences likely caused by microclimate using Hylocomium splendens, a moss with annual segments. We examined how spatio-temporal variation in drought across 3 years and 46 sites in central Sweden, affected the depth and magnitude of edge influences. We also investigated whether edge effects during drought were influenced by differences in forest structure. Edge effects were almost twice as strong in the drought year compared to the non-drought years, but we did not find clear evidence that they penetrated deeper into the forest in the drought year. Edge influences were also greater in areas that had fewer days with rain during the drought year. Higher levels of forest canopy cover and tree height buffered the magnitude of edge influence in times of drought. Our results demonstrate that edge effects are amplified by drought, suggesting that fragmentation effects are aggravated when droughts become more frequent and severe. Our results suggest that dense edges and buffer zones with high canopy cover can be important ways to mitigate negative drought impacts in forest edges.