Species‐specific trends and variability in plant functional traits across a latitudinal gradient in northern Alaska

Abstract

Questions Many studies explore how plant functional traits may change as the climate warms by observing traits over environmental gradients. The amount of intraspecific variation (ITV), however, is often unknown and unaccounted for in most trait‐based studies. Our objectives are to: (a) determine if species‐level patterns across a latitudinal gradient match those of other members within the same growth form; (b) compare distributions of trait values across regions; and (c) quantify the amount of ITV within each trait relative to the amount of variation within the growth form and across taxonomic levels (family and species). Location Utqiaġvik, Atqasuk, and Toolik Lake, Alaska. Methods This study examines seven plant functional traits for 12 arctic species. Traits were measured on 10 individuals of each species at each region and analyzed using one‐way ANOVA and variance partitioning via nested ANOVA. Results Comparison of mean trait values across the three regions for each species showed considerable variability within a growth form. Within deciduous shrubs, for example, one species increased in specific leaf area (SLA) with latitude while another species decreased. Results from variance partitioning differed among functional traits. Across the three regions, plant height, leaf area, SLA, leaf thickness, and leaf dry matter content (LDMC) had relatively low amounts of intraspecific variation (ITV; <15%) while normalized difference vegetation index (NDVI) had a high amount of ITV (>50%). All traits showed significant differences across regions for at least some species. Conclusions Because our results showed considerable variability in levels of ITV among functional traits, we emphasize the need to investigate ITV in trait‐based studies spanning multiple regions. Levels of ITV are important in determining how different populations respond to local environmental conditions. Incorporating ITV in studies investigating vegetation change with warming will provide more robust and reliable predictions.

Soil microenvironmental variation drives below‐ground trait variation and interacts with macroclimate to structure above‐ground trait variation of arctic shrubs

“…It is therefore expected to increase with temperature. However, leaf economic traits have been found to both increase and decrease along latitudinal and elevation gradients in arctic tundra ecosystems (Betway et al, 2021;Kudo et al, 2001). For example, Betway et al (2021) found that SLA of Salix pulchra increased from north to south, while Betula nana decreased.…”

“…However, leaf economic traits have been found to both increase and decrease along latitudinal and elevation gradients in arctic tundra ecosystems (Betway et al, 2021;Kudo et al, 2001). For example, Betway et al (2021) found that SLA of Salix pulchra increased from north to south, while Betula nana decreased. One potential explanation for these discrepancies is that the communities or sites where the species occur differ in soil moisture (Baruah et al, 2017;Betway et al, 2021).…”

“…For example, Betway et al (2021) found that SLA of Salix pulchra increased from north to south, while Betula nana decreased. One potential explanation for these discrepancies is that the communities or sites where the species occur differ in soil moisture (Baruah et al, 2017;Betway et al, 2021). Overall, our results highlight the need to account for microenvironmental conditions such as moisture and snow depth and cover that can limit plant response to climate change (Kemppinen & Niittynen, 2022).…”

“…Yet research also shows that patterns of intraspecific trait variation are idiosyncratic and depend on the spatial and ecological scales of investigation, as well as trait identity (Messier et al., 2010; Siefert et al., 2015; Westerband et al., 2021). For example, while climate and elevation have frequently been shown to drive intraspecific trait variation at regional spatial scales (Anderegg et al., 2021; Midolo et al., 2019; Ostonen et al., 2011; Zadworny et al., 2016), recent studies have documented substantial intraspecific trait variation within populations at local spatial scales (Betway et al., 2021; Burton et al., 2017; Kumordzi et al., 2019; Weemstra et al., 2021). This suggests that microenvironmental factors, like local soil properties and microclimate, may be just as or even more important for driving intraspecific trait variation (Kemppinen & Niittynen, 2022; Siefert et al., 2014).…”

The potential of trait data to increase the availability of bioindicators: A case study using plant conservatism values

“…Moreover, for the sake of operability and to facilitate integration of data into large databases (e.g., Bocci, 2015), traits are often simplified and treated as spatially constant and invariable within species, whereas bioindicator values may vary among regions based on available expertise and the criteria used. Even if we ignore phenotypic plasticity and intraspecific trait variability (Betway et al, 2021; Kumordzi et al, 2019) and assume that traits vary more between than within species, at least in richer assemblages (Escudero et al, 2021), interactions among traits still add complexity and possible uncertainty to trait‐based predictions of ecological conditions.…”