Variable species establishment in response to microhabitat indicates different likelihoods of climate‐driven range shifts

Kemppinen J., Lembrechts J.J., Van Meerbeek K., Carnicer J., Chardon N.I., Kardol P., Lenoir J., Liu D., Maclean I., Pergl J., Saccone P., Senior R.A., Shen T., Słowińska S., Vandvik V., et. al.

AbstractBrief introduction: What are microclimates and why are they important?Microclimate science has developed into a global discipline. Microclimate science is increasingly used to understand and mitigate climate and biodiversity shifts. Here, we provide an overview of the current status of microclimate ecology and biogeography in terrestrial ecosystems, and where this field is heading next.Microclimate investigations in ecology and biogeographyWe highlight the latest research on interactions between microclimates and organisms, including how microclimates influence individuals, and through them populations, communities and entire ecosystems and their processes. We also briefly discuss recent research on how organisms shape microclimates from the tropics to the poles.Microclimate applications in ecosystem managementMicroclimates are also important in ecosystem management under climate change. We showcase new research in microclimate management with examples from biodiversity conservation, forestry and urban ecology. We discuss the importance of microrefugia in conservation and how to promote microclimate heterogeneity.Methods for microclimate scienceWe showcase the recent advances in data acquisition, such as novel field sensors and remote sensing methods. We discuss microclimate modelling, mapping and data processing, including accessibility of modelling tools, advantages of mechanistic and statistical modelling and solutions for computational challenges that have pushed the state‐of‐the‐art of the field.What's next?We identify major knowledge gaps that need to be filled for further advancing microclimate investigations, applications and methods. These gaps include spatiotemporal scaling of microclimate data, mismatches between macroclimate and microclimate in predicting responses of organisms to climate change, and the need for more evidence on the outcomes of microclimate management.

Wilson R.N., Kopp C.W., Hille Ris Lambers J., Angert A.L.

AbstractAs ongoing climate change drives suitable habitats to higher elevations, species ranges are predicted to follow. However, observed range shifts have been surprisingly variable, with most species differing in rates of upward shift and others failing to shift at all. Disturbances such as fires could play an important role in accelerating range shifts by facilitating recruitment in newly suitable habitats (leading edges) and removing adults from areas no longer suited for regeneration (trailing edges). To date, empirical evidence that fires interact with climate change to mediate elevational range shifts is scarce. Resurveying historical plots in areas that experienced climate change and fire disturbance between surveys provides an exciting opportunity to fill this gap. To investigate whether species have tended to shift upslope and if shifts depend on fires, we resurveyed historical vegetation plots in North Cascades National Park, Washington, USA, an area that has experienced warming, drying, and multiple fires since the original surveys in 1983. We quantified range shifts by synthesizing across two lines of evidence: (1) displacement at range edges and the median elevation of species occurrences, and (2) support for the inclusion of interactions among time, fire and elevation in models of species presence with elevation. Among species that experienced fire since the original survey, a plurality expanded into new habitats at their upper edge. In contrast, a plurality of species not experiencing fire showed no evidence of shifts, with the remainder exhibiting responses that were variable in magnitude and direction. Our results suggest that fires can facilitate recruitment at leading edges, while species in areas free of disturbance are more likely to experience stasis.

Viejo R., Des M., Gutiérrez D.

There is growing emphasis on using fine-grained scales to identify the drivers of species’ geographic range edges, which is essential for predicting the response of species to climate change. This is of particular relevance at the ‘rear-edge’ of species distributions, where higher spatial resolution may also help in the detection of potential refugia for conservation. The southern edge of the range of several canopy-forming algae falls in the NW Iberian Peninsula, where large embayments (rias), influenced by strong upwelling events, may act as contemporary climatic refugia for these key coastal organisms. We investigated the factors driving the fine-scale occupancy patterns of the seaweed Fucus serratus, employing a combination of transplant experiments and a fine-grain species distribution model (SDM). Our study revealed that habitat suitability for this species is restricted to particular sites within rias. Transplant experiments showed that germling survival was significantly reduced outside the distribution range. Grazing may limit the species distribution towards the outer sections of rias, where we found the highest densities of grazing gastropods, but not towards the innermost sections. Both winter salinity and autumn seawater temperature were important predictors in the SDM. Our model projections indicate the potential future extirpation of F. serratus in rias with an increase of 1.5°C in maximum autumn temperature, below the predicted average warming of 2ºC for this upwelling area by the end of the century under the SSP5-8.5 scenario. The results highlight the importance of the autumn season for the performance of this cold-temperate seaweed at the southern edge of its range.

Chytrý K., Helm N., Hülber K., Moser D., Wessely J., Hausharter J., Kollert A., Mayr A., Rutzinger M., Winkler M., Pauli H., Saccone P., Paetzolt M., Hietz P., Dullinger S.

Complex topography regulates near‐surface temperature above the treeline. It may thus sustain microrefugia for alpine plants and relax the need of shifting upward when the climate warms. The effectiveness of these microrefugia rests on the premise that plant distributions in alpine landscapes are mainly controlled by fine‐scale topographic variation.We tested this assumption by relating the distribution of 79 plant species and 10 community attributes across 900 1 m² plots in a landscape spanning 1677 m of elevation to 17 topographical descriptors at resolutions between 1 and 301 m.We found that the presence of most species and most community attributes were better explained by topographic variation at coarser scales (> 20 m). Fine‐scale topography is more clearly reflected in moisture than in temperature requirements of species. The elevational gradient rather than topographic variation at any scale, is the single most important driver of both species distributions and the variation in community attributes in the area studied.We hypothesise that our results reveal a hitherto underestimated influence of spatial mass effects on alpine plant distributions. These effects can override environmental filtering at fine scales and will thus impede the survival of cold‐adapted plants in small and fragmented refugia under climate warming.

Xu C., De Frenne P., Blondeel H., De Pauw K., Landuyt D., Lorer E., Sanczuk P., Verheyen K., De Lombaerde E.

Understanding the distinct impacts of temperature and light on seedling growth is crucial for predicting forest regeneration trajectories under future climate change and forest disturbance. This is because temperature and light can change independently or together, influencing the competitive status of tree seedlings and forest herbs. However, most prior studies tend to explore temperature and light effects either separately or in combination, lacking comprehensive full-factorial designs. Here, we utilized two large-scale full-factorial experiments to explore warming and light effects on tree seedlings growing in mesocosms with herbaceous plants. We found that light increased seedling height, diameter, and biomass, while warming alone had no significant effects. Moreover, we observed that there was an interaction effect between light and warming, where warming increased seedling height, diameter, and biomass under illumination. Understory herbaceous plant cover alone did not affect seedling height, diameter, and biomass, but it decreased seedling biomass when mesocosms were warmed or illuminated. This highlights the importance of considering the indirect negative effects induced by the interaction between forest opening and understory herbaceous plants. By disentangling the effects of increased temperature and light availability on understory seedling height, diameter, and biomass, our results contribute valuable knowledge for future forest management. It is imperative to carefully control the size of the gaps artificially created to facilitate the understory regeneration. Small gaps are recommended considering that the herbaceous plants may interact with both warming and light to negatively affect seedlings.

Hiiesalu I., Schweichhart J., Angel R., Davison J., Doležal J., Kopecký M., Macek M., Řehakova K.

Abstract Arbuscular mycorrhizal (AM) fungi can benefit plants under environmental stress, and influence plant adaptation to warmer climates. However, very little is known about the ecology of these fungi in alpine environments. We sampled plant roots along a large fraction (1941–6150 m asl (above sea level)) of the longest terrestrial elevational gradient on Earth and used DNA metabarcoding to identify AM fungi. We hypothesized that AM fungal alpha and beta diversity decreases with increasing elevation, and that different vegetation types comprise dissimilar communities, with cultured (putatively ruderal) taxa increasingly represented at high elevations. We found that the alpha diversity of AM fungal communities declined linearly with elevation, whereas within-site taxon turnover (beta diversity) was unimodally related to elevation. The composition of AM fungal communities differed between vegetation types and was influenced by elevation, mean annual temperature, and precipitation. In general, Glomeraceae taxa dominated at all elevations and vegetation types; however, higher elevations were associated with increased presence of Acaulosporaceae, Ambisporaceae, and Claroideoglomeraceae. Contrary to our expectation, the proportion of cultured AM fungal taxa in communities decreased with elevation. These results suggest that, in this system, climate-induced shifts in habitat conditions may facilitate more diverse AM fungal communities at higher elevations but could also favour ruderal taxa.

Man M., Kalčík V., Macek M., Brůna J., Hederová L., Wild J., Kopecký M.

Abstract Microclimates have been recognised as one of the key drivers in global change biology. Durable microclimate loggers, detailed in‐situ measurements and sophisticated modelling tools are increasingly available, but a lack of standardised workflows for microclimate data handling hinders synthesis across the studies and thus progress in the global change biology. To overcome these limitations, we developed an R package myClim for microclimate data processing, storage and analyses. The myClim package supports complete workflow for microclimate data handling, including reading raw logger data files, their preprocessing and cleaning, time‐series' aggregation, calculation of ecologically relevant microclimatic variables, data export and storage. The myClim package stores data in a size‐efficient, hierarchical structure which respects the hierarchy of field microclimate measurement (locality > loggers > sensors). For imported microclimatic data, myClim provides an informative summary and automatically detects and corrects common issues like duplicated and wrongly ordered measurements. The myClim package also provides advanced functions for microclimate data aggregation to various timescales (e.g. days, months, years or growing seasons) as well as tools for sensor calibration, data conversion and joining of multiple microclimatic time series. The myClim package provides advanced functions for standardised calculation of ecologically relevant microclimatic variables like freezing and growing degree days, snow cover period, soil volumetric water content and atmospheric vapour pressure deficit. Calculated microclimatic variables are stored efficiently in myClim data format and can be easily exported to long or wide tables for further analyses and visualisations. Adopting myClim can facilitate large‐scale syntheses, boost data sharing and increase the comparability and reproducibility of microclimatic studies. The stable version of myClim is available on CRAN (https://cran.r‐project.org/web/packages/myClim) and the development version is available on GitHub (https://github.com/ibot‐geoecology/myClim).

Patiño J., Collart F., Vanderpoorten A., Martin‐Esquivel J.L., Naranjo‐Cigala A., Mirolo S., Karger D.N.

AbstractAimUnderstanding how grain size affects our ability to characterize species responses to ongoing climate change is of crucial importance in the context of an increasing awareness for the substantial difference that exists between coarse spatial resolution macroclimatic data sets and the microclimate actually experienced by organisms. Climate change impacts on biodiversity are expected to peak in mountain areas, wherein the differences between macro and microclimates are precisely the largest. Based on a newly generated fine‐scale environmental data for the Canary Islands, we assessed whether data at 100 m resolution is able to provide more accurate predictions than available data at 1 km resolution. We also analysed how future climate suitability predictions of island endemic bryophytes differ depending on the grain size of grids.LocationCanary Islands.Time periodPresent (1979–2013) and late‐century (2071–2100).TaxaBryophytes.MethodsWe compared the accuracy and spatial predictions using ensemble of small models for 14 Macaronesian endemic bryophyte species. We used two climate data sets: CHELSA v1.2 (~1 km) and CanaryClim v1.0 (100 m), a downscaled version of the latter utilizing data from local weather stations. CanaryClim also encompasses future climate data from five individual model intercomparison projects for three warming shared socio‐economic pathways.ResultsSpecies distribution models generated from CHELSA and CanaryClim exhibited a similar accuracy, but CanaryClim predicted buffered warming trends in mid‐elevation ridges. CanaryClim consistently returned higher proportions of newly suitable pixels (8%–28%) than CHELSA models (0%–3%). Consequently, the proportion of species predicted to occupy pixels of uncertain suitability was higher with CHELSA (3–8 species) than with CanaryClim (0–2 species).Main conclusionsThe resolution of climate data impacted the predictions rather than the performance of species distribution models. Our results highlight the crucial role that fine‐resolution climate data sets can play in predicting the potential distribution of both microrefugia and new suitable range under warming climate.

Sanczuk P., De Pauw K., De Lombaerde E., Luoto M., Meeussen C., Govaert S., Vanneste T., Depauw L., Brunet J., Cousins S.A., Gasperini C., Hedwall P., Iacopetti G., Lenoir J., Plue J., et. al.

Macroclimatic changes are impacting ecosystems worldwide. However, a large portion of terrestrial species live under conditions where impacts of macroclimate change are buffered, such as in the shade of trees, and how this buffering impacts future below-canopy biodiversity redistributions at the continental scale is unknown. Here we show that shady forest floors due to dense tree canopies mitigate severe warming impacts on forest biodiversity, while canopy opening amplifies macroclimate change impacts. A cross-continental transplant experiment in five contrasting biogeographical areas combined with experimental heating and irradiation treatments was used to parametize 25-m resolution mechanistic demographic distribution models and project the current and future distributions of 12 common understorey plant species, considering the effects of forest microclimate and forest cover density. These results highlight microclimates and forest density as powerful tools for forest managers and policymakers to shelter forest biodiversity from climate change. The impacts of microclimate on future plant population dynamics are poorly understood. The authors use large-scale transplant climate change experiments to show the contribution of forest microclimates to population dynamics and project the distributions of 12 common understorey plants.

Allsup C.M., George I., Lankau R.A.

Climate change is pushing species outside of their evolved tolerances. Plant populations must acclimate, adapt, or migrate to avoid extinction. However, because plants associate with diverse microbial communities that shape their phenotypes, shifts in microbial associations may provide an alternative source of climate tolerance. Here, we show that tree seedlings inoculated with microbial communities sourced from drier, warmer, or colder sites displayed higher survival when faced with drought, heat, or cold stress, respectively. Microbially mediated drought tolerance was associated with increased diversity of arbuscular mycorrhizal fungi, whereas cold tolerance was associated with lower fungal richness, likely reflecting a reduced burden of nonadapted fungal taxa. Understanding microbially mediated climate tolerance may enhance our ability to predict and manage the adaptability of forest ecosystems to changing climates.

Muñoz Mazon M., Klanderud K., Sheil D.

Abstract Context Tropical mountains are hotspots of plant diversity, with a remarkable density of narrow ranged and endemic species. To develop effective in situ strategies for the conservation of species under changing climatic conditions we need to understand the mechanisms that shape their distributions. Objectives We explore how disturbance shapes the elevation ranges of two shrubs and eight tree species (Hypericum irazuense, Vacciunium consanguineum, Escallonia myrtilloides, Schefflera rodriguesiana, Weinmannia pinnata, Rhamnus (Frangula) oreodendron, Styrax argenteus, Podocarpus oleifolius, Prumnopitys standleyi, Magnolia poasana) characteristic of the paramos and cloud forest of the Talamanca Mountains, Costa Rica. Methods We used distance sampling transects along a 1400 m elevation range and “density surface models” to explore how the distribution of the selected species responds to changes in basal area and light availability after disturbance, across their elevation range. Results The legacies of disturbance on forest structure and light availability clearly shaped the elevation ranges of seven species. H. irazuense had a clear light demanding strategy, only occurring at well-lit sites throughout their range. V. consanguineum, E. myrtilloides and S. rodriguesiana shifted from a shade tolerant to strictly light demanding distribution between their upper and lower range limit, showing a context dependent role of light availability along their elevation range. R. oreodendron, S. argenteus and W. pinnata occurred mainly under shaded and crowded conditions. The density of M. poasana, P. oleifolius and P. standleyi species was related only to elevation. Conclusions Our study illustrates how light availability and disturbance are key to understand the elevation range dynamics of high elevation tropical trees and shrubs. Canopy openings after disturbances provide habitat for paramo and high elevation woody plant species to persist under warmer conditions. These findings can inform conservation efforts aimed at preserving high elevation plants species in the future.

Lembrechts J.J.

The speed at which terrestrial organisms are shifting their ranges in response to climate is consistently lower than that predicted by models. However, the use of microclimate-based, rather than macroclimate-based, predictions virtually eliminates these discrepancies.

Maclean I.M., Early R.

Current conservation policy has been shaped by the expectation that, for many species, places with suitable climate will lie outside their current range, thus leading to predictions of numerous extinctions. Here we show that the magnitude of range shifts is often overestimated as climate data used do not reflect the microclimatic conditions that many organisms experience. We model the historic (1977–1995) distributions of 244 heathland and grassland plant taxa using both macro- and microclimate data and project these distributions to present day (2003–2021). Whereas macroclimate models predicted major range shifts (median 14 km shift), microclimate models predicted localized shifts, generally of less than 1 km, into favourable microclimates that more closely match observed patterns of establishment and extirpation. Thus, improving protection of refugial populations within species’ existing geographic range may, for species living in environments exposed to sunlight, be more effective than assisted translocations and overhaul of protected area networks. The authors model historic and current distributions of grassland and heathland plants using both macro- and microclimate data. While macroclimate models predict the need for major range shifts (14 km median), microclimate models predict much smaller shifts that more closely match observed patterns.

Franklin J.

Stickley S.F., Fraterrigo J.M.

Species distribution models (SDMs) largely rely on free-air temperatures at coarse spatial resolutions to predict habitat suitability, potentially overlooking important microhabitat. Integrating microclimate data into SDMs may improve predictions of organismal responses to climate change and support targeting of conservation assets at biologically relevant scales, especially for small, dispersal-limited species vulnerable to climate-change-induced range loss. We integrated microclimate data that account for the buffering effects of forest vegetation into SDMs at a very high spatial resolution (3 m2) for three plethodontid salamander species in Great Smoky Mountains National Park (North Carolina and Tennessee). Microclimate SDMs were used to characterize potential changes to future plethodontid habitat, including habitat suitability and habitat spatial patterns. Additionally, we evaluated spatial discrepancies between predictions of habitat suitability developed with microclimate and coarse-resolution, free-air climate data. Microclimate SDMs indicated substantial losses to plethodontid ranges and highly suitable habitat by mid-century, but at much more conservative levels than coarse-resolution models. Coarse-resolution SDMs generally estimated higher mid-century losses to plethodontid habitat compared to microclimate models and consistently undervalued areas containing highly suitable microhabitat. Furthermore, microclimate SDMs revealed potential areas of future gain in highly suitable habitat within current species’ ranges, which may serve as climatic microrefugia. Taken together, this study highlights the need to develop microclimate SDMs that account for vegetation and its biophysical effects on near-surface temperatures. As microclimate datasets become increasingly available across the world, their integration into correlative and mechanistic SDMs will be imperative for accurately estimating organismal responses to climate change and helping environmental managers tasked with spatially prioritizing conservation assets.

Bontrager M., Worthy S.J., Cacho N.I., Leventhal L., Maloof J.N., Gremer J.R., Schmitt J., Strauss S.Y.

AbstractQuantifying species’ niches across a clade reveals how environmental tolerances evolve, and offers insights into present and future distributions. Niche construction occurs when species select subsets of suitable conditions from those available, and influences niche evolution. We use herbarium specimens to explore climate niche evolution in 14 annual species of theStreptanthus/Caulanthusclade (Brassicaceae), which originated in deserts and subsequently diversified into cooler, moister areas. We quantify the “lived climate” of specimens from germination, estimated from historical climate records at collection sites, to collection date. We compare these specimen-based, phenologically-specific climate niches to typical annual climate niches and to standardized seasonal niches from the same localities. We also explore the role of spatial microrefugia in shaping lived climate by analyzing field soil samples collected for each species, and by comparing soil texture at collection localities to random locations nearby using soil databases. Specimen-specific climate achieved through niche construction revealed much less clade-wide temperature niche variation than annual and seasonal niches. Species track hotter and drier climates in cooler regions by growing later into the summer, and by inhabiting spatial refugia of drought-prone soils. All climate metrics evolved in a manner consistent with or more constrained than Brownian motion except specimen-specific temperature niches, which showed limited clade-wide variation and no phylogenetic signal. Limited variation in specimen-specific climate niches across the clade underscores how niche construction moderates experienced climate and may impact species’ responses to climate change.Significance statementHere, we show that species across a clade that appear to have diverged in their climate niches based on annual conditions are actually tracking very similar seasonal climate conditions. This climate similarity is achieved through both the evolution of seasonal phenology and through establishment in suitable spatial refugia. Our results highlight the importance of niche construction in climate adaptation and the diversification of species, as well as the need to consider phenology when assessing and predicting habitat suitability. Restricted climate niches imply that species may be less adaptable than we expect based on annual climate diversity, and have implications for conservation and management.

Corlett R.T.

Lyn Morelli T., Hallworth M.T., Duclos T., Ells A., Faccio S.D., Foster J.R., McFarland K.P., Nislow K., Ralston J., Ratnaswamy M., Deluca W.V., Siren A.P.

A primary prediction of climate change ecology is that species will track their climate niche poleward and upslope. However, studies have shown species responding in surprising ways. In this study, we aim to understand the impact of global change on species ranges by considering both climate and habitat changes. Using occupancy analysis of acoustic survey data in the mountains of the northeastern United States, we tested specific predictions of range responses to warming (shifting upslope), precipitation change (shifting downslope), and forest composition change (shifting downslope). We found that American red squirrels Tamiasciurus hudsonicus, key nodes in northern North American food webs, are not tracking increasing temperatures upslope, despite substantial warming in recent decades. Structural equation modeling indicates that red squirrel abundance is primarily influenced by red‐spruce forest cover, which has shifted downslope with recovery from historical logging and acid deposition. Accounting for the multiple dimensions of global change will enable better predictions and more effective conservation strategies.

Goodwin K.J., Chardon N.I., Pradhan K., Hille Ris Lambers J., Angert A.L.

Climate change is causing many species' ranges to shift upslope to higher elevations as species track their climatic requirements. However, many species have not shifted in pace with recent warming (i.e. ‘range stasis'), possibly due to demographic lags or microclimatic buffering. The ‘lagged‐response hypothesis' posits that range stasis disguises an underlying climatic sensitivity if range shifts lag the velocity of climate change due to slow colonization (i.e. colonization credits) or mortality (i.e. extinction debt). Alternatively, the ‘microclimatic buffering hypothesis' proposes that small‐scale variation within the landscape, such as canopy cover, creates patches of suitable habitat within otherwise unsuitable macroclimates that create climate refugia and buffer range contractions. We simultaneously test both hypotheses by combining a large seed addition experiment of 25 plant species across macro‐ and micro‐scale climate gradients with adult occurrence records to compare patterns of seedling recruitment relative to adult ranges and microclimate in the North Cascades, USA. Despite high species‐to‐species variability in recruitment, community‐level patterns monitored for five years supported the lagged response hypothesis, with a mismatch between where seedlings recruit versus adults occur. On average, the seedling recruitment optimum shifted from the adult climatic range centre to historically cooler, wetter regions and many species recruited beyond their cold (e.g. leading) range edge. Meanwhile, successful recruitment occurred at warm and dry edges, despite recent climate change, suggesting that macroclimatic effects on recruitment do not drive trailing range dynamics. We did not detect evidence of microclimatic buffering due to canopy cover in recruitment patterns. Combined, our results suggest apparent range stasis in our system is a lagged response to climate change at the cool ends of species ranges, with range expansions likely to occur slowly or in a punctuated fashion.