Ecological Monographs

Understanding the factors that drive community-wide assembly of plant-pollinator systems along environmental gradients has considerable evolutionary, ecological and applied significance. Variation in thermal environments combined with intrinsic differences among pollinators in thermal biology (tolerance limits, thermal optima, thermoregulatory ability) have been proposed as drivers of community-wide pollinator gradients, but this suggestion remains largely speculative. We test the hypothesis that seasonality in bee pollinator composition in montane habitats of southeastern Spain, which largely reflects the prevalence during the early flowering season of mining bees (Andrena), is a consequence of the latters thermal biology. Quantitative information on seasonality of Andrena bees in the whole plant community (275 plant species) was combined with field and laboratory data on key aspects of the thermal biology of 30 species of Andrena (endothermic ability, warming constant, relationships of body temperature with ambient and operative temperatures). Andrena bees were a conspicuous, albeit strongly seasonal component of the pollinator assemblage of the regional plant community, visiting flowers of 153 different plant species (57% of total). Proportion of Andrena relative to all bees reached a maximum among plant species which flowered in late winter and early spring, and declined precipitously from May onwards. Andrena were recorded only during the cooler segment of the annual range of air temperatures experienced at flowers by the whole bee assemblage. These patterns can be explained by features of Andrenas thermal biology: null or negligible endothermy; ability to forage at much lower body temperature than endothermic bees (difference ~10{degrees}C); low upper tolerable limit of body temperature, beyond which thermal stress presumably precluded foraging at the warmest period of year; weak thermoregulatory capacity; and high warming constant enhancing ectothermic warming. Our results demonstrate the importance of lineage-specific pollinator traits as drivers of seasonality in community-wide pollinator composition; show that exploitation of cooler microclimates by bees does not require endothermy; falsify the frequent assumption that endothermy and thermoregulation apply to all bees; and suggest that medium- and large-sized ectothermic bees with low upper thermal limits and weak thermoregulatory ability can actually be more adversely affected by climate warming than large endothermic species.

SummaryO_LIHistorically, terrestrial biosphere models (TBMs) have assigned the intrinsic (maximum) quantum yield of photosynthesis ({varphi}0) a constant value for each plant functional type. However, experimental studies have shown that {varphi}0- when measured on light-adapted leaves - depends on temperature. It is unclear whether this dependence is universal or biome-specific; how it is manifested at the ecosystem level; and how it should be represented in TBMs. C_LIO_LIBy fitting empirical light-response curves to a global set of eddy-covariance CO2 flux measurements and correcting for photorespiration, we inferred apparent, ecosystem-level {varphi}0values and their temperature responses across a wide range of environments. C_LIO_LIThe temperature response of apparent ecosystem-level {varphi}0 follows a universal bell-shaped curve. The shape of this curve does not markedly differ among biomes, but the maximum value of {varphi}0 decreases with increasing aridity, its temperature optimum increases with increasing growth temperature, and its sensitivity to temperature increases as growth temperature declines. C_LIO_LIOur model for {varphi}0(T) aligns with recent theory highlighting the role of cytochrome b6f in regulating the light reactions of photosynthesis. If implemented in TBMs, this model should allow better predictions of the responses of terrestrial ecosystem function to a warming climate. C_LI

Earth is home to millions of plant and animal species, with more than 40 thousand species facing extinction worldwide (Diaz et al. 2019). Species range size is particularly important in this context because it influences extinction risk (Purvis et al. 2000, Gaston & Fuller 2009), but the causes underlying the wide natural variation in range size remain poorly known. Here, we investigate how evolutionary age is related to present-day range size for over 25,000 species of mammals, birds, reptiles, amphibians, reef fishes, and plants. We show that, on average, older species have significantly larger ranges, but the effect of age on range size is modulated by clade, geographical context and dispersal ability. Specifically, age does not affect range size for island species, because islands limit dispersal and hence range size, regardless of species age. Furthermore, species from clades with high dispersal capabilities obtain large ranges faster, thereby further neutralizing the relationship between age and range size. Our results can help supporting global conservation priorities, by showing that species that are young, occupy islands, and/or are dispersal limited often have small ranges and therefore increased extinction risk.

1Climate change is expected to bring about changes in precipitation and temperature regimes that, together with rising atmospheric CO2 concentrations, will likely reorganise the functional trait composition of ecosystems. Predicting plant trait responses to emerging environmental conditions including, in particular, water availability, is a tremendous challenge, but is one that eco-evolutionary optimality theory (EEO) can help us undertake. However, most EEO approaches are based on the hypothesis that traits are selected to maximise carbon assimilation which omits the important role that size growth plays in determining fitness outcomes. Using a height-growth based EEO framework, we predict magnitude and directional shifts in four key traits: leaf mass per area, sapwood area to leaf area ratio (Huber value), wood density and sapwood-specific conductivity in response to variation in soil moisture availability, atmospheric aridity, CO2 and light availability. Consistent with empirical patterns, we predict that trait optima shift from resource-acquisitive strategies characterised by low tissue constructions costs and high rates of tissue turnover and sapwood conductivity to resource-conservative strategies - characterised by low rates of tissue turnover and greater xylem embolism resistance - as conditions become increasingly dry. The EEO model that we use here highlights the important role that both carbon assimilation and tissue construction costs jointly play in predicting the response of trait optima to the environment, laying the groundwork for future height-growth based EEO models aiming to predict shifts in the functional composition of ecosystems in response to global change.

Leading an effective response to the accelerating crisis of anthropogenic climate change will require improved understanding of global carbon cycling. A critical source of uncertainty in Earth Systems Models (ESMs) is the role of microbes in mediating both the formation and decomposition of soil organic matter, and hence in determining patterns of CO2 efflux. Traditionally, ESMs model carbon turnover as a first order process impacted primarily by abiotic factors, whereas contemporary biogeochemical models often explicitly represent the microbial biomass and enzyme pools as the active agents of decomposition. However, the combination of non-linear microbial kinetics and ecological heterogeneity across space guarantees that upscaled dyamics will violate mean-field assumptions via Jensens Inequality. Violations of mean-field assumptions mean that parameter estimates from models fit to upscaled data (e.g. eddy covariance towers) are likely systematically biased. Here we present a generic mathematical analysis of upscaled michaelis-menten kinetics, grounded in Scale Transition Theory. We advance the framework by providing solutions in dimensionless form, and illustrate how this approach facilitates qualitative insight into the significance of this scale transition, and argue that it will facilitate future cross site intercomparisons of scale transition effects from flux data. We also discuss the critical terms that need to be constrained in order to unbias parameter estimates.

Accurate projections of temperate tree growing seasons under climate change require representing developmental constraints that determine tree resource allocation. Recent work has identified a phenological "switch point" after the summer solstice (21 June), with pre-solstice warming advancing autumn phenology and post-solstice warming delaying it. Here, we propose this switch is flexible and occurs at the compensatory point between the antagonistic effects of early-season development and late-season temperature. We performed trans-solstice climate manipulation experiments on potted European beech (Fagus sylvatica) saplings to test (i) how spring leaf-out timing and June-August temperatures influence end-of-season timing (bud set and leaf senescence [50% loss of leaf chlorophyll content]), and (ii) whether daytime and nighttime temperatures before and after the solstice have different effects, given that trees primarily grow at night. Bud set and leaf senescence responses were tightly coupled (R2 = 0.49), with bud responses being generally stronger. Each day delay in spring leaf-out delayed bud set by 0.24 {+/-} 0.06 days and senescence by 0.22 {+/-} 0.08 days. Post-solstice full-day cooling in July delayed autumn phenology in late-leafing individuals (bud set +4.9 {+/-} 2.6 days; senescence +3.1 {+/-} 2.8 days) but had negligible impact on early-leafing trees (bud set +1.4 {+/-} 2.6 days; leaf senescence +2.2 {+/-} 2.8 days). Conversely, August full-day cooling advanced both stages. Daytime cooling before the solstice had no effect, while after the solstice it advanced autumn phenology. Nighttime cooling always delayed bud set. These findings support the Solstice-as-Phenology-Switch model and highlight the central role of developmental progression in constraining growing seasons. Faster early-season development -especially under nighttime warming- moves trees past the switch earlier, increasing sensitivity to late-season cooling and thereby triggering earlier autumn phenology. To improve growing season length projections, phenology models should account for these developmentally-mediated and diel-specific temperature responses.

Our current understanding of the relationship between insect herbivory and ecosystem productivity is limited. Previous studies have typically quantified only leaf area loss, or have been conducted during outbreak years. These set-ups often ignore the physiological changes taking place in the remaining plant tissue after insect attack, or may not represent typical, non-outbreak herbivore densities. Here, we estimate the amount of carbon lost to insect herbivory in a temperate deciduous woodland both through leaf area loss and, notably, through changes in leaf gas exchange in non-consumed leaves under non-outbreak densities of insects. We calculate how net primary productivity changes with decreasing and increasing levels of herbivory, and estimate what proportion of the carbon involved in the leaf area loss is transferred further in the food web. We estimate that the net primary productivity of an oak stand under ambient levels of herbivory is 54 - 69% lower than that of a completely intact stand. The effect of herbivory quantified only as leaf area loss (0.1 Mg C ha-1 yr-1) is considerably smaller than when the effects of herbivory on leaf physiology are included (8.5 Mg C ha-1 yr-1). We propose that the effect of herbivory on primary productivity is non-linear and mainly determined by changes in leaf gas exchange. We call for replicated studies in other systems to validate the relationship between insect herbivory and ecosystem productivity described here.

As canopy closure causes forest stands to face increasing light limitation, trees lower branches begin to die back. This process, called self-pruning, defines a crowns base and depth and shapes the structure of entire stands. Self-pruning is often thought to occur after shading causes individual branches to transition from net carbon sources to sinks. Under this explanation, we would expect resource-conservative and shade-tolerant species to initiate self-pruning under deeper shade because their branches need less light to maintain a positive carbon balance. However, the notion that branches are fully autonomous may be complicated by correlative inhibition, in which plants preferentially allocate resources towards sunlit branches. Consistent with this idea, we predicted that within species, trees with sunlit tops would initiate self-pruning at a higher light threshold. Lastly, we predicted that plot-level diversity in self-pruning strategies would correlate with productivity and total crown volume. We tested these predictions in an experiment where 12 temperate tree species were planted in plots of varying diversity and composition. We measured characteristics of crown size and position as well as the light level at the crown base (denoted Lbase), which we took as an estimate of the light threshold of self-pruning. As we predicted, more shade-tolerant and resource-conservative species self-pruned at a deeper level of shade (lower Lbase). In addition, most species had higher Lbase when they had more light at the crown top, suggestive of correlative inhibition. With respect to their neighbors traits, though, conservative and acquisitive species showed contrary patterns of plasticity: conservative species had lower Lbase around conservative neighbors, while acquisitive species had lower Lbase around acquisitive neighbors. However, all species declined in crown depth when they grew alongside larger, more acquisitive neighbors. As predicted, plots with a greater interspecific diversity of Lbase had greater basal area and crown volume. Using simulations, we showed that plasticity in crown depth between monocultures and mixtures strengthened the relationship with crown volume, primarily due to competitive release experienced by acquisitive species. By placing shade-induced self-pruning in a comparative context, we clarify how forest function emerges from competition for light between individual trees.

Complementarity between functional analogues can confer resistance and resilience on ecosystems in the face of environmental change. High biodiversity can lead to increased ecosystem functionality through complementary effects. Earthworms, woodlice and millipedes can have high densities in leaf litter and soils, but little is known about their seasonal patterns. The two groups play important roles in the breakdown and incorporation of organic matter into soils. Differences in peak abundance could affect the rates of litter break down and incorporation in different seasons. We sampled earthworms, woodlice and millipedes from leaf litter soil every month for ten years in a New Forest woodland. We used non-parametric regression to explore monthly and yearly variation in the abundance of decomposer organisms and soil temperature and moisture. Earthworms have a distinct seasonal peak in density different from woodlice and millipedes. Earthworm peak density is in the winter and spring and is correlated with greatest soil moisture. Woodlice (and millipede) have their peak density is in the summer and is correlated with the highest soil temperatures. This means that earthworms, woodlice and millipedes have complementary peaks in abundance. These two groups have similar functional roles in litter decomposition and these data imply ecological complementarity in this important ecological process. This effect is likely to be widespread in lowland woodland in the UK and Europe, with only extreme temperatures and low pH limiting the distribution. Increased summer drought as a result of climate change may lead to changes in the relative abundance of these three groups and in particular local extinctions of earthworms which will in turn affect litter decomposition.

Understanding the effects of climate change on the evolution of phenological timing, such as start of flowering, is of major interest because phenology is critical for fitness of populations, and underpins many ecological dynamics. Much recent research has focused on the correlation between phenological timing and the arrival of spring. However, the evolutionarily optimal seasonal timing should depend also on the duration of the growing season, within which entire annual life cycles must unfold. Optimal energy allocation theory can explicitly address life-history scheduling in a seasonal environment, and be used to predict how scheduling should adaptively respond to seasonality shifts. Here we extend a seminal theoretical framework for perennial plant scheduling by Iwasa & Cohen (1989), and predict a specific nonlinear relationship between growing season length and optimal flowering time expressed as number of days after the start of the growing season. We tested and found strong support for this a priori prediction in two independent common-garden experiments with purple loosestrife (Lythrum salicaria) and European goldenrod (Solidago virgaurea) populations sampled along latitudinal gradients in Sweden. Climate warming is commonly associated with changes in both the start and the duration of the growing season. Considering both effects, our findings suggest that as springs start earlier and growing seasons lengthen, shifts in optimal flowering time expressed as calendar date may initially stall before accelerating, potentially explaining observed variation in phenological shifts across systems. More broadly, we show how mechanistic life history theory can advance understanding of phenological change beyond correlative conclusions. SIGNIFICANCE STATEMENTThe optimal timing for a plant to flower depends both on when spring begins and on the total length of the growing season--both shifting with climate change. However, the adaptation of flowering time to changes in growing season length is much less explored than to an advancing spring. Building on existing theory, we predict a nonlinear relationship between growing season length and optimal flowering time. Data on two species (purple loosestrife and European goldenrod) grown in common gardens strongly support this prediction. Our results demonstrate why species can vary in their observed phenological responses to climate change. More broadly, we highlight the power of mechanistic life history theory for explaining and predicting phenological shifts.

Subalpine forests worldwide face the synergistic threats of global warming and increased biotic attack, and the collapse or transition of subalpine forests is predicted in south-eastern Australia under future climates. The recent widespread dieback of subalpine snow gum forests due to increased activity of a native wood-boring longicorn beetle suggests this process may already be underway. We investigated how variation in tree tissue traits and environmental conditions correlated with elevation-dependent spatial patterns of forest mortality. We hypothesised that increased vulnerability of subalpine snow gums to wood-borer-mediated dieback at intermediate elevations was associated with poorly-resolved differences in traits between montane (Eucalyptus pauciflora subsp. pauciflora) and subalpine (E. pauciflora subsp. niphophila) snow-gum subspecies. We first sought to characterise variation and elevation-dependent transitions in 20 structural and drought-related functional traits among 120 healthy trees distributed along a 1000m elevation transect which spanned the subspecies transition zone. Secondly, we surveyed 774 trees across 53 sites between 1280-1980m asl. to explore associations between borer-damage severity, elevation, subspecies, and a subset of traits that differed between subspecies. These snow-gum subspecies exhibited mean differences and/or divergent elevation responses in 25% of traits surveyed, indicating contrasting suites of traits between montane and subalpine subspecies. Increased borer-damage severity across the montane-to-subalpine subspecies transition was correlated with lower bark thickness, whereas reduced borer damage at the highest elevations was associated with greater precipitation and lower temperatures. Our results suggest that due to possessing distinct traits associated with increased borer susceptibility, subalpine snow-gum forests will be subject to increased risk of severe borer-mediated forest dieback under warmer and drier future climates. Identifying traits contributing to species distribution limits and biotic-agent vulnerability remains critical for predicting, monitoring, and possibly mitigating forest and vegetation declines under future climates.

Ectomycorrhizae are widespread symbionts of higher plants. However, their benefits for plant productivity and growth have not been well demonstrated since many studies do not suggest any improvement of plant growth or of plant nutrition for mycorrhizal plants. We use mechanistic modelling based on the population dynamics of decomposers to simulate the coexistence of mycorrhizal and non-mycorrhizal plants as well as the development of the soil decomposer community. The model assumed a fixed stoichiometry of each decomposer functional type. Decomposer growth depended on its carbon and nitrogen uptake. For mycorrhiza a part of the carbon is modelled to be supplied from the plant while a fixed proportion of the mycorrhizal nitrogen uptake is translocated to the plant. Carbon nitrogen ratios of decomposers were adjusted mineralization of nitrogen or overflow respiration of carbon. The results suggest that mycorrhizal plants do often outcompete non-mycorrhizal plants at no or little improvement of plant productivity. The main mechanism of mycorrhizal dominance is a reduction of the soil inorganic nitrogen pool and a rerouting of the nitrogen uptake of plants to the transfer nitrogen transfer from mycorrhizae to plants. On the other hand carbon subsidies from the trees allow to expand the niche of mycorrhizal fungi and to outcompete saprohytic fungi under a wide range of physiological and environmental parameters. This leads to dominance of mycorrhizal plants under a broad range of conditions and parameters including low transfer rates of nitrogen from the mycorrhiza to the plant, and low allocation of the plants to mycorrhiza. Significance statementThe paper uses mechanistic, population based modelling to explain the dominance of ectomycorrhizal plants in northern ecosystems while there is limited evidence that these increase plant productivity. We demonstrate that rerouting of the nitrogen cycle towards provision of organic nitrogen to the plant allows mycorrhizal plants to outcompete non-mycorrhizal competitors. Simultaneously, mycorrhizae benefit from carbon subsidies in their competition with saprophytic fungi and bacteria.

Floral scents are an important mediator of many plant-pollinator interactions. However, environmental and ecological change could affect the synthesis and emission of volatile chemicals that constitute floral scents, potentially influencing pollinator perception of scents. We investigated the effects of elevation and warming on the floral scents of multiple co-occurring alpine meadow plant species along an elevational gradient in the Eastern Himalayas (3000 - 4000 masl). We also investigated pollinator responses in the same locations using 3-D printed floral models that replicated the differing volatile constituents. Finally, we assessed how pollinator preferences changed with variations in elevation, flowering season and location. We found that elevation and in-situ warming using Open Top Chambers (OTC) led to significant intraspecific variation in the composition of floral scents, both in terms of quality and quantity of volatiles released. Nevertheless, conspecific floral scents across elevations were more similar to each other than to other species. Cafeteria assays using artificial floral models revealed that pollinator preferences were driven by a small number of volatiles (p-cymene, 2-pentylfuran and -pinene), but these preferences were abolished in a novel plant-pollinator community where the same floral volatiles were not detected. Our results suggest that the local odourscape established by the floral community present plays a key role in plant-pollinator interactions. This emphasizes the need to incorporate ecological impacts such as changes in community into climate change analyses to understand the long-term impacts of human activity on co-evolutionary relationships like pollination. Significance StatementFloral scents are important for most plant-pollinator interactions, and can be affected by environmental factors like elevation and temperature. Our study shows that elevation and simulated in situ warming change the composition of floral scents, yet scents from the same species were more similar to each other across elevations and temperatures than to other species. Further, pollinator preferences to these scents replicated in artificial models persisted in spite of variation in temperature and elevation, but not in a novel plant-pollinator community containing floral species not releasing those volatiles. This emphasizes the need to incorporate factors such as floral community composition into our understanding of the long-term impacts of climate change and human activity on co-evolutionary relationships like pollination.

Understanding how species abundances are driven by biotic interactions along environmental gradients is a fundamental question in ecology. For abundances at competitive equilibria in Central European forests, a classical ecological theory formulated by Ellenberg (1963) predicts that beech (Fagus sylvatica L.) outcompetes other tree species within a mesic range of soil pH and water levels, while other species prevail under less favorable conditions. While the theory is generally accepted in forest ecology, only certain aspects of it have been substantiated by empirical evidence. Moreover, the demographic processes driving the turnover from beech to other tree species at the extremes of the soil gradients remain mostly unexplained. To address this, we inversely calibrated a parsimonious forest model (JAB model) with a sapling stage and interacting populations with short time series of observed tree abundances from the German national forest inventory. By modelling how demographic rates vary along pH and soil water gradients, we were able to test the prediction that beech naturally predominates only at favorable soil conditions. Moreover, we tested with simulations how the environmental response of demographic rates explains Fagus changing relative abundance along the soil gradients. Our results largely confirm that Fagus out competes other species in a central environmental range. Environmental change of Fagus relative abundance is primarily explained by environmental variation of its net basal area increment, followed by its competition response at the overstory and at the sapling stage. We found that even though sapling tolerance to shading is the primary mechanism for Fagus predominance, it only plays a secondary role for the environmental variation of its relative abundance. Synthesis: By inverse calibration of a forest population model with demographic rates that respond to the environment, we confirm the predictions of Ellenbergs classical, albeitonlypartially-evidenced, theory on F. sylvaticas predominance in Central European forests. Furthermore, for thefirsttime, we substantiate the theory by elucidating how the environmental variation in species composition is based in demographic processes. This demonstrates that our approach can be utilized to predict distributions of interacting species and to explain the dynamics between species, as influenced by their environment.

AimAbiotic factors, such as temperature and precipitation, vary markedly along elevational gradients, and can in turn, shape key biotic interactions, such as herbivory and pollination. Despite the well-known effects of climatic conditions on pollinator activity and efficiency, we know little about the role of climate in pollinator shifts in animal-pollinated plants at broad geographic scales. Here we investigate patterns of altitudinal turnover in pollination mode across the Americas, with a focus on the most common pollinators (bees and hummingbirds). Specifically, we test Crudens classic hypothesis that plants are likely to shift to bird pollination at high elevations because endothermic pollinators are more reliable in cold and rainy conditions. LocationAmericas Time periodCurrent Major taxa studied2232 plant taxa from 26 clades MethodsWe collated information on pollination mode (1262 insect-pollinated, 970 vertebrate-pollinated) for the study taxa from the literature, and used GBIF occurrence data to estimate median distributions and bioclimatic attributes of each species. We used (phylogenetic) GLMMs to test for associations between pollination mode and ecogeographic variables. ResultsTo our surprise, we found flipped elevational patterns of insect- and vertebrate-pollination strategies across latitudes, with vertebrate pollination dominating at high elevations in the tropics, but not in temperate zones. We term this pattern the Tropical flip. We recovered a strong association of vertebrate-pollinated plants with moist, forested habitats across latitudes, while insect-pollinated plants were often found in cool and dry or warm and moist conditions. Main conclusionsAltitudinal gradients in temperature may not serve as a universal explanation for shifts among endothermic insect and ectothermic vertebrate pollination. Instead, strong abiotic niche differentiation among insect- and vertebrate-pollinated plants, along with competition for pollination niche space, has likely shaped the tropical flip.

Climate change is expected to alter forest community composition and functioning, with consequences for the ecosystem services forests provide. However, most macroecological projections focus on individual species distributions and offer limited insight into whether entire communities will remain functionally compatible with future climatic conditions. Here we quantify the risk that present-day forest communities will become functionally misaligned with projected climates using a trait-based approach. We analysed forest inventory data from more than 42,000 mature plots across the United States and Canada. For each plot we estimated community-weighted means for 24 functional traits describing leaf economics, hydraulic function, wood structure, abiotic tolerances and symbiotic strategies. We modelled relationships between community functional composition and environmental conditions, and used these relationships to estimate the trait profiles most compatible with projected late-century climates (2080-2100). Trait-environment misalignment (TEM) risk was quantified as the multivariate distance between current community trait composition and the trait profile associated with the projected future climate at each location, accounting for covariance among traits and intraspecific trait variation. Projected climatic conditions favour trait combinations associated with greater hydraulic capacity and reduced cold and shade tolerance. However, the magnitude of functional misalignment varies strongly across space. The highest TEM risk occurs in high-latitude and montane conifer forests across western and central North America, whereas many mid-latitude broadleaf and mixed forests show lower risk because projected climatic changes reinforce existing drought-adapted functional strategies. Critically, high species richness was the strongest predictor of reduced risk, reinforcing the importance of biodiversity in buffering against adverse outcomes. Our results suggest that many forests are projected to experience climatic conditions associated with functional strategies that differ from those characterising the current community. By identifying where the largest functional adjustments are implied, this trait-based framework provides a scalable way to pinpoint forests most likely to experience suboptimal climate conditions and to prioritise monitoring and climate-adapted management.

The space for time substitution posits that warmer locations can provide a source of genetic variation that could be adaptive for future climate change conditions. While this approximation might be useful for planning assisted gene flow, it relies on the importance of abiotic adaptations over biotic ones. Here I address this gap by assessing influence of anti-herbivore defenses, phenology, and morphology on the seed production of 146 populations of Oenothera biennis close to the plants cold range limit. Genotypes from 2.1{degrees} South of the common garden produce more seeds than most northern lineages. Adaptations across space are a suitable substitute for climate change, but there is still substantial fitness variability. These differences were best explained by bolt date, flowering time, and greater defenses against herbivores. Given the impacts of climate change, plant defenses might already be of similar adaptive importance to phenology close to northern rage limits.

O_LIMacroalgal (seaweed) beds and forests fuel coastal ecosystems and are rapidly reorganising under global change, but quantifying their functional structure still relies on binning species into coarse groups on the assumption that they adequately capture relevant underlying traits.\nC_LIO_LITo interrogate this \"group gambit\", we first measured 12 traits relating to competitive dominance and resource economics across 95 macroalgal species collected from UK rocky shores. We then assessed trait variation explained by traditional grouping approaches consisting of (i) two highly-cited schemes based on gross morphology and anatomy and (ii) two commonly-used categorisations of vertical space use. To identify the limitations of traditional grouping approaches and to reveal potential alternatives, we also assessed the ability of (iii) emergent groups created from post hoc clustering of our dataset to account for macroalgal trait variation.\nC_LIO_LI(i) Traditional groups explained about a third of multivariate trait expression with considerable group overlap. (ii) Classifications of vertical space use accounted for even less multivariate trait expression. Notwithstanding considerable overlap, the canopy vs. turf scheme explained significant differences in most individual traits, with turf species tending to display attributes of opportunistic forms. (iii) Emergent groups were substantially more parsimonious than all existing grouping approaches.\nC_LIO_LISynthesis: Our analysis using a comprehensive dataset of directly measured functional traits failed to strongly support the group gambit in macroalgae. While existing grouping approaches may allow first order approximations, they risk considerable loss of information at the trait and, potentially, ecosystem levels. We call for further development of a trait-based approach to macroalgal functional ecology to capture unfolding community and ecosystem changes with greater accuracy and generality.\nC_LI

O_LIClimate change poses extreme risks to biodiversity, threatening the ecosystems upon which humanity depends. Understanding the traits that mediate how organisms respond to climatic gradients in space and time will enable better predictions of the taxa and ecological communities most at risk from warming. C_LIO_LIIn insects, colouration influences thermoregulation, but warming responses must be traded off against other selective pressures. We hypothesise that butterfly wing reflectance in visible and near-infrared (NIR) spectra respond differently to temperature and ultraviolet radiation over space and time. We combined existing reflectance data of 97 butterfly species in both NIR and visible wavelengths, with long-term abundance monitoring data of 120 butterfly communities sampled across 1650 m altitude gradients from May to August in two time periods (2004/5 and 2017). C_LIO_LIThe visible and NIR reflectances of butterfly communities showed a non-linear relationship with altitude, with the lowest reflectance (darkest butterflies) at the coolest, highest sites. In contrast, community visible reflectance decreased through the year as temperatures warmed over spring-summer, whereas community NIR reflectance remained constant, revealing divergent responses of reflectance types to seasonal changes. Temperature had opposing effects on visible and NIR reflectance of butterfly communities, where increasing temperature reduced community visible reflectance strongly while increasing community NIR reflectance slightly. C_LIO_LIConsidering the effects on reflectance of shared evolutionary history in a Bayesian hierarchical model for individual species, lighter-coloured (more reflective) species were associated with warmer temperatures - flying later in spring-summer or at lower altitudes. However, instead of decreasing in reflectance through the year and across temperature gradients, species instead became lighter, we expect as a result of a Simpsons paradox. C_LIO_LIThese results emphasise how visible and NIR reflectance wavelength bands mediate butterflies responses to environmental gradients in distinct ways, despite being highly correlated across species. We also show that incorporating phylogeny into trait-environment models is essential; relying on traits alone would lead to incorrect inferences and predictions of taxa most at risk from warming climates. C_LI

ContextSpatially explicit drivers of foliar chemical traits link plants to ecosystem processes to reveal landscape functionality. Specifically, foliar elemental, stoichiometric, and phytochemical (ESP) compositions represent key indicator traits. ObjectivesHere, we investigate the spatial drivers of foliar ESP at the species level and across species at the trait level for five commonly occurring boreal forest understory plants. MethodsOn the island of Newfoundland, Canada, we collected foliar material from four chronosequenced forest grids. Using response variables of foliar elemental (C, N, P, percent and quantity), stoichiometric (C:N, C:P, N:P), and phytochemical (terpenoids) composition, we tested multiple competing hypotheses using spatial predictors of land cover (e.g., coniferous, deciduous, mixedwood), productivity (e.g., enhanced vegetation index), biotic (e.g., stand age/height, canopy closure) and abiotic (e.g., elevation, aspect, slope) factors. ResultsWe found evidence to support spatial relationships of foliar ESP for most species (mean R2 = 0.22, max = 0.65). Spatial variation in elemental quantity traits of C, N, P were related to land cover along with biotic and abiotic factors for 2 of 5 focal species. Notably, foliar C, C:P, and sesquiterpene traits between different species were related to abiotic factors. Similarly, foliar terpenoid traits between different species were related to a combination of abiotic and biotic factors (mean R2 = 0.26). ConclusionsSpatial-trait relationships mainly occur at the species level, with some commonalities occurring at the trait level. By linking foliar ESP traits to spatial predictors, we can map plant chemical composition patterns that influence landscape-scale ecosystem processes.