Microclimate relationships of intraspecific trait variation in sub-Arctic plants

Within-species trait variation is a substantial part of plant functional diversity. However, this intraspecific trait variation (ITV) is rarely investigated in relation to a key characteristic of the Arctic and alpine ecosystems: fine-scale microclimatic heterogeneity. Here, we quantified the influence of microclimate (soil moisture, snow and local temperatures) on plant functional traits, specifically on ITV. We focused on six widespread northern latitude vascular plant species, and measured four traits: plant height, leaf area, leaf dry matter content (LDMC) and specific leaf area (SLA). We related ITV to field and remotely sensed microclimate data from 150 study plots within six study grids. The grids were located within a 76-m altitudinal belt in three environments: the tundra, tundra-forest ecotone and mountain birch forest in Kilpisjarvi, northwestern Finland. We compared the range of trait values between this local trait dataset (n = 5493) and global trait databases (n = 10 383). We found that information in the local dataset covers a relatively large portion of the trait ranges in global databases. The proportion varies among traits and species; the largest portion was 74% for variation in leaf area of Vaccinium uliginosum, and the lowest was 19% for LDMC of Betula nana. We found that ITV in height was mostly related to local temperatures, whereas SLA and LDMC were more related to soil moisture and snow conditions. However, species showed contrasting relationships with the microclimate drivers. We conclude that microclimate profoundly shapes ITV in northern latitude plants and that even a very compact geographic area can contain a large amount of ITV. The influence of the microclimatic conditions varies among functional traits and species, which indicates that plastic response or adaptive potential of the species to climate change may also vary across species, but that necessary variation may often be present within local plant populations.Peer reviewe

Maaperän kosteus arktisessa maisemassa

The spatial and temporal variations in soil moisture can cause natural hazards, such as droughts and floods. Soil moisture and its mediating environmental factors are fairly unknown from the point of view of climate change, even though climate is a major controlling factor. A significant feedback loop between climate and soil moisture affects various ecosystem processes, especially in the Arctic. Soil moisture is fairly fast and simple to measure in the field, but even so it has not been the subject of comprehensive research. Especially the temporal changes in soil moisture in the Arctic are poorly understood. In low-energy systems, such as Arctic-alpine regions, soil moisture is an important limiting factor for vegetation. This study aims to understand which factors mediate soil moistures spatial variation and temporal change. In addition, one of the objectives of this study is to determine the importance of soil moisture for vascular plant distribution at the landscape scale. The data comprehends 945 individual square meter plots from a 130 km² research area in northern Norway, where relative elevation reaches almost 1000 meters. The variable relief covers a vast range of extreme environmental gradients over short distances, such as a moisture gradient from dry, sun-baked slopes to water-logged peatlands and a vegetation gradient from rugged mountain tops to flood-meadows rich in species. The data consists of in situ field measurements and observations as well as data based on topography, remote sensing and climate models. Factors controlling the spatial variation and temporal change of soil moisture are studied with multivariate models (GLM: Generalized linear model and GAM: Generalizes additive model) at different scales. The importance of soil moisture for vegetation is examined by using four modelling techniques (GLM, GAM, GBM: Generalized boosted regression model, and RF: Random forest) within BIOMOD, an ensemble platform for species distribution modelling. Soil moisture is mediated by various factors, but this research stresses soil properties as the most important variable for the spatial variation in soil moisture conditions. Temporal changes in moisture are mainly controlled by climate factors along with soil properties. Throughout all scales, vegetation, topography, and snow were also proven to be important factors. Vegetation distribution is controlled by soil moisture, as several previous studies have shown. Moisture models based on field measurements as opposed to wetness indices based on topography (SWI: Saga wetness index) turned out to have higher coefficient values. In addition to soil moisture, other soil properties and radiation also control vegetation distribution. The least meaningful factor was shown to be SWI, emphasizing the irreplaceability of field measurements. There are several positive and negative feedbacks between soil moisture and its controlling factors, which need to be addressed when investigating soil moisture. The results of this study are in line with previous studies concerning both moisture controlling factors and soil moisture as a limiting resource for vegetation. The novelty of this study lies in its approach: bringing various spatiotemporal scales together in order to find factors controlling moisture an Arctic landscape. After all, soil moisture is first and foremost controlled by soil properties, but it is also mediated by various factors at different scales.Maaperän kosteuden alueellinen ja ajallinen vaihtelu on voimakasta, ja kosteuden ääritilat aiheuttavat sekä kuivuusjaksoja että tulvia. Kosteutta ja sitä sääteleviä ympäristötekijöitä on tutkittu verrattain vähän ilmastonmuutostutkimuksen yhteydessä, vaikka maaperän kosteus on keskeinen osa arktisen ympäristön ekosysteemiprosesseja ja toimintoja. Tutkimuksenkohteena kosteus on verrattain yksinkertainen ja nopea mitata, mutta kosteutta ei kuitenkaan ole kattavasti tutkittu, etenkään kosteuden ajallista vaihtelua ja muutosta arktisilla alueilla. Erityisesti niukkaresurssisilla arktis-alpiinisilla alueilla, eli karulla metsänrajan ylipuolisella paljakalla, kosteus on merkittävä kasvillisuutta rajoittava resurssi. Tämän tutkimuksen tavoitteena on selvittää, mitkä ympäristötekijät säätelevät maaperän kosteuden alueellista vaihtelua ja ajallista muutosta arktisessa ympäristössä, minkä lisäksi tarkastellaan kosteuden merkitystä putkilokasvien levinneisyydelle maisematasolla. Maaperä- ja kasvillisuusaineisto kerättiin 945 neliömetrin tutkimusruudulta, 130 km² tutkimusalueelta Pohjois-Norjasta, missä suhteellista korkeuseroa on lähes kilometri. Vaihteleva korkokuva kattaa lyhyilläkin etäisyyksillä laajan kirjon voimakkaita ympäristögradientteja: kosteusgradientin kuivilta paahderinteiltä vettyneille turvemaille ja kasvillisuusgradientin karuilta tunturihuipuilta lajirikkaille sulamisvesiniityille. Tutkimusaineisto koostuu maastosta kerätystä mittaus- ja havainnointiaineistosta sekä topografiaan, kaukokartoitukseen ja ilmastomalliin pohjautuvista aineistoista. Kosteuden alueellista vaihtelua ja ajallista muutosta selittävien ympäristötekijöiden tutkimiseen käytettiin kahta monimuuttujamenetelmää (GLM: Generalized linear model ja GAM: Generalized additive model) eri mittakaavatasoilla ja kosteuden merkitystä kasvillisuuden levinneisyydelle tarkasteltiin BIOMOD-menetelmäkokoelman neljällä menetelmällä (GLM, GAM, GBM: Generalized boosted model ja RF: Random forest). Maaperän kosteuteen vaikuttavat useat ympäristötekijät, mutta monimuuttujamallinnuksen tuloksena maaperän ominaisuudet osoittautuivat tärkeimmiksi alueellisen vaihtelun selittäjiksi ja ilmaston ohella tärkeimmiksi ajallisen muutoksen selittäjiksi. Maaperän ominaisuuksien lisäksi kaikilla mittakaavatasoilla alueellista vaihtelua selittävät kasvillisuus, topografia, ilmasto ja lumi. Ajallista muutosta selittävät maaperän ominaisuuksien ja ilmaston lisäksi topografia ja lumi. Putkilokasvien levinneisyyden selittäjänä kosteus osoittautui muita ympäristötekijöitä merkittävämmäksi ja kosteusmalli ennustekyvyltään paremmaksi kuin topografiaan pohjautuva kosteusindeksimalli (SWI: Saga wetness index). Kosteuden lisäksi myös muut maaperän ominaisuudet ja säteily selittävät putkilokasvien levinneisyyttä, kun taas vähäisin merkitys on SWI:llä, mikä korostaa kentällä kerättyjen kosteusmittausten tärkeyttä. Kosteuden voimakas vaihtelu on seurausta erilaisista ympäristöolosuhteista, mutta kosteus myös luo erilaisia ympäristöjä. Kosteuden ja ympäristötekijöiden yhteisvaikutukset ja takaisinkytkennät ovat merkittävässä osassa tarkasteltaessa kosteutta. Tässä tutkimuksessa löydettiin aikaisemmin todettuja teoreettisen viitekehyksen osoittamia yhteyksiä sekä kosteuden ja sitä säätelevien ympäristötekijöiden väliltä että kosteuden ja kasvillisuuden väliltä, mutta tutkimuksessa tuotiin myös uusia lähestymistapoja kosteuden tutkimukseen yhdistämällä hienonmittakaavan tuloksia laajan maisematason tarkasteluun. Maaperän kosteus on ennen kaikkea paikallisten olosuhteiden säätelemää, mutta siihen vaikuttavat lukuisat ympäristötekijät eri mittakaavatasoilla

Soil moisture and its importance for tundra plants

Water is fundamental for plant life, as it affects the growth, survival, and spatial patterns of vegetation. Here, I explored soil moisture and its ecosystem effects to answer: 1) What controls soil moisture variation? 2) How is water linked to vegetation? 3) Do plants influence water resources? I focused on the moisture of the top-soil layer (0 – 10 cm) in Fennoscandian mountain tundra. First, I evaluated environmental conditions controlling soil moisture variation. I used different modelling methods (generalized linear models, generalized additive models, generalized boosted regression models, and random forests) to account for the uncertainties related to each multivariate technique. On average, the model fit was R2 = 0.60 and the predictive performance R2 = 0.47. The spatial variation of soil moisture was most related to a topographic proxy of soil water accumulation and the depth of the organic soil layer. These results demonstrated that moisture can be modelled using topography and soil data. Secondly, I examined the influence of three water aspects (spatial and temporal variation of soil moisture, and fluvial disturbance) on vascular plants, mosses, and lichens. I used species distribution modelling, a framework for analysing the spatial patterns of species in relation to the environment. The species groups were most related to the spatial variation of soil moisture, albeit species had diverse responses. In general, water is not scarce in the tundra, yet the water aspects improved the models highlighting water as a multifaceted driver of the ecosystem. In addition, I investigated if plant-environment relationships were universal in the tundra. Here, I used hierarchical generalized additive models to compare sites across the hemispheres. I combined plant trait records with data on their environmental drivers. The local variation of conditions within the sites was overridden by global relationships indicating that these links are generalisable across the tundra sites. The results provide empirical evidence for a fundamental assumption in community ecology: consistent plant-environment relationships. Last, I introduced plants to my first question regarding controls of soil moisture. I considered other factors potentially influencing vegetation and soil conditions by using structural equation modelling, a theory-based hierarchical modelling technique. Woody plants correlated negatively with soil moisture, soil temperature, and soil organic carbon stocks (standardised coefficients = -0.16; -0.22; -0.27). As the abundance of woody plants increases, they feedback into the climate system through the water, energy, and carbon cycles. To conclude, plant-water relationships are strong across the tundra. Soil moisture and its spatial variation are controlled by the soil characteristics and the topographic features in the landscape, but also by the abundance of woody plants. Water conditions affect vegetation across species groups, from individuals to the communities. This knowledge unravels the importance of soil moisture in a vulnerable ecosystem undergoing rapid changes.Vesi on välttämätöntä elämälle, myös kasveille. Vesi vaikuttaa kasvillisuuden kasvuun, eloonjääntiin ja alueelliseen esiintyvyyteen. Tässä väitöskirjassa tutkin maaperän kosteutta ja sen vaikutuksia paljakkaekosysteemiin vastaamalla seuraaviin kysymyksiin: 1) Mikä vaikuttaa maaperän kosteuden vaihteluun? 2) Kuinka vesi kytkeytyy kasvillisuuteen? 3) Vaikuttavatko kasvit vesiresursseihin? Tutkimuksissani tarkastelin pintamaan (0 – 10 cm) kosteutta Fennoskandian tunturipaljakalla. Väitöskirjani ensimmäisessä osassa tutkin kosteuden säätelijöitä. Käytin useita tilastollisia mallinnusmenetelmiä (yleistä lineaarista mallia, yleistä additiivista mallia, yleistettyä luokittelupuu menetelmää ja satumetsää), sillä kaikissa on omat epävarmuustekijänsä. Keskimäärin mallin istuvuus oli R2 = 0.60 ja ennustuskyky R2 = 0.47. Kosteuden alueellista vaihtelua sääteli eniten pinnanmuotoihin perustuva kosteusindeksi ja turpeen paksuus. Tulokset osoittavat, että kosteutta voi mallintaa topografia- ja maaperäaineistolla. Toisessa osassa tarkastelin kolmea vesimuuttujaa (kosteuden alueellista ja ajallista vaihtelua sekä veden aiheuttamia häiriöitä) ja niiden vaikutusta putkilokasveihin, sammaleisiin ja jäkäliin. Käytin lajimallinnusta, joka on kehitetty lajien ja niitä säätelevien tekijöiden alueelliseen tarkasteluun. Kolmesta vesimuuttujasta kaikkia lajiryhmä sääteli eniten kosteuden alueellinen vaihtelu. Vesimuuttujat paransivat malleja, mikä osoittaa, että vesi vaikuttaa suuresti paljakkaekosysteemissä, missä vedestä ei yleensä ole pulaa. Lisäksi tutkin kasvien ja ympäristön välistä suhdetta ja sen yleistettävyyttä paljakalla. Käytin hierarkkista yleistä additiivista mallia vertaillakseni alueita kummaltakin pallonpuoliskoilta. Tarkastelin kasvien toiminnallisten ominaisuuksien säätelijöitä. Paikallista ympäristövaihtelua merkittävämpää oli kasvien ja ympäristön johdonmukainen suhde. Tulokset osoittavat todeksi yhden toiminnallisen ekologian tärkeimmistä olettamuksista: kasvien ja ympäristön suhde on yleismaailmallinen. Viimeisessä osassa palasin ensimmäiseen kysymykseeni kasvien kera. Käytin rakenneyhtälömallia, joka on teoriaperusteinen hierarkkinen menetelmä ja mahdollistaa taustamuuttujien huomioimisen. Puuvartinen kasvillisuus korreloi negatiivisesti maaperän kosteuden, maaperän lämpötilan ja maaperän eloperäisen hiilivaraston kanssa (standardoidut kertoimet = -0.16; -0.22; -0.27). Kun paljakka ympäristö pensastuu, puuvartinen kasvillisuus tulee vaikuttamaan ilmastoon veden, energian ja hiilen kierron kautta Johtopäätökseni on, että kasvien ja veden välinen vuorovaikutussuhde on voimakas paljakalla. Maaperän kosteus ja sen alueellinen vaihtelu on maaperän ja pinnanmuotojen säätelemää, mutta myös puuvartinen kasvillisuus säätelee sitä. Vesiolot vaikuttavat kasvillisuuden eri lajiryhmiin, niin yksilöihin kuin yhteisöihin. Tämä tieto korostaa kosteuden merkitystä herkässä ekosysteemissä, jota koettelevat suuret mullistukset

Modelling soil moisture in a high-latitude landscape using LiDAR and soil data

Soil moisture has a pronounced effect on earth surface processes. Global soil moisture is strongly driven by climate, whereas at finer scales, the role of non-climatic drivers becomes more important. We provide insights into the significance of soil and land surface properties in landscape-scale soil moisture variation by utilizing high-resolution light detection and ranging (LiDAR) data and extensive field investigations. The data consist of 1200 study plots located in a high-latitude landscape of mountain tundra in north-western Finland. We measured the plots three times during growing season 2016 with a hand-held time-domain reflectometry sensor. To model soil moisture and its temporal variation, we used four statistical modelling methods: generalized linear models, generalized additive models, boosted regression trees, and random forests. The model fit of the soil moisture models were R-2 = 0.60 and root mean square error (RMSE) 8.04 VWC% on average, while the temporal variation models showed a lower fit of R-2 = 0.25 and RMSE 13.11 CV%. The predictive performances for the former were R-2 = 0.47 and RMSE 9.34 VWC%, and for the latter R-2 = 0.01 and RMSE 15.29 CV%. Results were similar across the modelling methods, demonstrating a consistent pattern. Soil moisture and its temporal variation showed strong heterogeneity over short distances; therefore, soil moisture modelling benefits from high-resolution predictors, such as LiDAR based variables. In the soil moisture models, the strongest predictor was SAGA (System for Automated Geoscientific Analyses) wetness index (SWI), based on a 1m(2) digital terrain model derived from LiDAR data, which outperformed soil predictors. Thus, our study supports the use of LiDAR based SWI in explaining fine-scale soil moisture variation. In the temporal variation models, the strongest predictor was the field-quantified organic layer depth variable. Our results show that spatial soil moisture predictions can be based on soil and land surface properties, yet the temporal models require further investigation. Copyright (c) 2017 John Wiley & Sons, Ltd.Peer reviewe

Relationships between above-ground plant traits and carbon cycling in tundra plant communities

The trait composition and trait diversity of plant communities are globally applicable predictors of ecosystem functioning. Yet, it is unclear how plant traits influence carbon cycling. This is an important question in the tundra where vegetation shifts are occurring across the entire biome, and where soil organic carbon stocks are large and vulnerable to environmental change. To study how plant traits affect carbon cycling in the tundra, we built a model that explained carbon cycling (above-ground and soil organic carbon stocks, and photosynthetic and respiratory fluxes) with abiotic conditions (air temperature and soil moisture), and the averages and within-community variabilities of three above-ground traits: plant height, leaf dry matter content (LDMC) and SLA. These functional parameters were represented by abundance-weighted means and standard deviations of species traits. The data were collected from an observational study setting from northern Finland. The explanatory power of the models was relatively high, but a large part of variation in soil organic carbon stocks remained unexplained. Average plant height was the strongest predictor of all carbon cycling variables except soil carbon stocks. Communities of larger plants were associated with larger CO2 fluxes and above-ground carbon stocks. Communities with fast leaf economics (i.e. high SLA and low LDMC) had higher photosynthesis, ecosystem respiration and soil organic carbon stocks. Within-community variability in plant height, SLA and LDMC affected ecosystem functions differently. Variability in SLA and LDMC increased CO2 fluxes and soil organic carbon stocks, while variability in height increased the above-ground carbon stock. The contributions of within-community trait variability metrics to ecosystem functioning within the study area were about as important as those of average SLA and LDMC. Synthesis. Plant height, SLA and LDMC have clear effects on tundra carbon cycling. The importance of within-community trait variability highlights a potentially important mechanism controlling the vast tundra carbon pools that should be better recognized. More research on root traits and decomposer communities is needed to understand the below-ground mechanisms regulating carbon cycling in the tundra.Peer reviewe

Dwarf Shrubs Impact Tundra Soils : Drier, Colder, and Less Organic Carbon

In the tundra, woody plants are dispersing towards higher latitudes and altitudes due to increasingly favourable climatic conditions. The coverage and height of woody plants are increasing, which may influence the soils of the tundra ecosystem. Here, we use structural equation modelling to analyse 171 study plots and to examine if the coverage and height of woody plants affect the growing-season topsoil moisture and temperature (< 10 cm) as well as soil organic carbon stocks (< 80 cm). In our study setting, we consider the hierarchy of the ecosystem by controlling for other factors, such as topography, wintertime snow depth and the overall plant coverage that potentially influence woody plants and soil properties in this dwarf shrub-dominated landscape in northern Fennoscandia. We found strong links from topography to both vegetation and soil. Further, we found that woody plants influence multiple soil properties: the dominance of woody plants inversely correlated with soil moisture, soil temperature, and soil organic carbon stocks (standardised regression coefficients = - 0.39; - 0.22; - 0.34, respectively), even when controlling for other landscape features. Our results indicate that the dominance of dwarf shrubs may lead to soils that are drier, colder, and contain less organic carbon. Thus, there are multiple mechanisms through which woody plants may influence tundra soils.Peer reviewe

A methodological guide to observe local-scale geodiversity for biodiversity research and management

Current global environmental change calls for comprehensive and complementing approaches for biodiversity conservation. According to recent research, consideration of the diversity of Earth's abiotic features (i.e. geodiversity) could provide new insights and applications into the investigation and management of biodiversity. However, methods to map and quantify geodiversity at local scale have not been developed although this scale is important for conservation planning. Here, we introduce a field methodology for observing plot-scale geodiversity, pilot the method in an Arctic–alpine tundra environment, provide empirical evidence on the plot-scale biodiversity–geodiversity relationship and give guidance for practitioners on the implementation of the method. The field method is based on observation of geofeatures, that is, elements of geology, geomorphology and hydrology, from a given area surrounding a location of species observations. As a result, the method provides novel information on the variation of abiotic nature for biodiversity research and management. The method was piloted in northern Norway and Finland by observing geofeatures from 76 sites at three scales (5, 10 and 25 m radii). To explore the relationship between measures of biodiversity and geodiversity, the occurrence of vascular plant species was recorded from 2 m × 2 m plots at the same sites. According to the results, vascular plant species richness was positively correlated with the richness of geofeatures (Rs = 0.18–0.59). The connection was strongest in habitats characterized by deciduous shrubs. The method has a high potential for observing geofeatures without extensive geological or geomorphological training or field survey experience and could be applied by conservation practitioners. Synthesis and applications. Consideration of geodiversity in understanding, analysing and conserving biodiversity could facilitate environmental management and ensure the long-term sustainability of ecosystem functions. With the developed method, it is possible to cost-efficiently observe the elements of geodiversity that are useful in ecology and biodiversity conservation. Our approach can be adapted in different ecosystems and biodiversity investigations. The method can be adjusted depending on the abiotic conditions, expertise of the observer(s) and the equipment available.publishedVersio

Modelling spatio-temporal soil moisture dynamics in mountain tundra

Abstract Soil moisture has a fundamental influence on the processes and functions of tundra ecosystems. Yet, the local dynamics of soil moisture are often ignored, due to the lack of fine resolution, spatially extensive data. In this study, we modelled soil moisture with two mechanistic models, SpaFHy (a catchment-scale hydrological model) and JSBACH (a global land surface model), and examined the results in comparison with extensive growing-season field measurements over a mountain tundra area in northwestern Finland. Our results show that soil moisture varies considerably in the study area and this variation creates a mosaic of moisture conditions, ranging from dry ridges (growing season average 12 VWC%, Volumetric Water Content) to water-logged mires (65 VWC%). The models, particularly SpaFHy, simulated temporal soil moisture dynamics reasonably well in parts of the landscape, but both underestimated the range of variation spatially and temporally. Soil properties and topography were important drivers of spatial variation in soil moisture dynamics. By testing the applicability of two mechanistic models to predict fine-scale spatial and temporal variability in soil moisture, this study paves the way towards understanding the functioning of tundra ecosystems under climate change. This article is protected by copyright. All rights reserved.Peer reviewe

Geomorphological processes shape plant community traits in the Arctic

Aim Geomorphological processes profoundly affect plant establishment and distributions, but their influence on functional traits is insufficiently understood. Here, we unveil trait-geomorphology relationships in Arctic plant communities. Location High-Arctic Svalbard, low-Arctic Greenland and sub-Arctic Fennoscandia. Time period 2011-2018. Major taxa studied Vascular plants. Methods We collected field-quantified data on vegetation, geomorphological processes, microclimate and soil properties from 5,280 plots and 200 species across the three Arctic regions. We combined these data with database trait records to relate local plant community trait composition to dominant geomorphological processes of the Arctic, namely cryoturbation, deflation, fluvial processes and solifluction. We investigated the relationship between plant functional traits and geomorphological processes using hierarchical generalized additive modelling. Results Our results demonstrate that community-level traits are related to geomorphological processes, with cryoturbation most strongly influencing both structural and leaf economic traits. These results were consistent across regions, suggesting a coherent biome-level trait response to geomorphological processes. Main conclusions The results indicate that geomorphological processes shape plant community traits in the Arctic. We provide empirical evidence for the existence of generalizable relationships between plant functional traits and geomorphological processes. The results indicate that the relationships are consistent across these three distinct tundra regions and that geomorphological processes should be considered in future investigations of functional traits.Peer reviewe

Geomorphological processes shape plant community traits in the Arctic

Aim Geomorphological processes profoundly affect plant establishment and distributions, but their influence on functional traits is insufficiently understood. Here, we unveil trait-geomorphology relationships in Arctic plant communities. Location High-Arctic Svalbard, low-Arctic Greenland and sub-Arctic Fennoscandia. Time period 2011-2018. Major taxa studied Vascular plants. Methods We collected field-quantified data on vegetation, geomorphological processes, microclimate and soil properties from 5,280 plots and 200 species across the three Arctic regions. We combined these data with database trait records to relate local plant community trait composition to dominant geomorphological processes of the Arctic, namely cryoturbation, deflation, fluvial processes and solifluction. We investigated the relationship between plant functional traits and geomorphological processes using hierarchical generalized additive modelling. Results Our results demonstrate that community-level traits are related to geomorphological processes, with cryoturbation most strongly influencing both structural and leaf economic traits. These results were consistent across regions, suggesting a coherent biome-level trait response to geomorphological processes. Main conclusions The results indicate that geomorphological processes shape plant community traits in the Arctic. We provide empirical evidence for the existence of generalizable relationships between plant functional traits and geomorphological processes. The results indicate that the relationships are consistent across these three distinct tundra regions and that geomorphological processes should be considered in future investigations of functional traits.Peer reviewe