Microclimate relationships of intraspecific trait variation in sub‐Arctic plants

Abstract

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 Kilpisjärvi, 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.

Soil Moisture Variations From Boreal Forests to the Tundra

“…In boreal forests, soil moisture is strongly linked to photosynthesis, tree growth and survival, and forest fires (Bartsch et al., 2009; D'Orangeville et al., 2016; Reich et al., 2018), and in the tundra, to biodiversity, shrubification, and overall climate change impacts on ecosystem functions (Ackerman et al., 2017; Bjorkman et al., 2018; le Roux et al., 2013). Overall, soil moisture is crucial for plants and other soil dwelling organisms, as many species and their specific traits are specialized for certain hydrological conditions (Kemppinen & Niittynen, 2022; Lowry et al., 2011; Silvertown et al., 2015). Pronounced spatial heterogeneity in soil moisture can thus be an important agent in providing versatile habitats, and consequently, promoting biodiversity (McLaughlin et al., 2017).…”

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

“…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).…”

“…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). Multiple environmental drivers could also operate together or potentially interact across scales to structure intraspecific trait variation because multiple resources limit plant growth (i.e.…”

“…Previous studies in tundra ecosystems show that intraspecific trait variation accounts for 17%–74% of the total variation for common size‐structural (plant height, leaf size) and leaf economics traits (Jónsdóttir et al., 2023; Kemppinen & Niittynen, 2022; Thomas et al., 2020). For most traits, intraspecific trait variation has been found to be highest at local scales (<10 km 2 ), suggesting microenvironmental heterogeneity partly structures plant trait distributions (Thomas et al., 2020).…”

Deciduous Tundra Shrubs Shift Toward More Acquisitive Light Absorption Strategy Under Climate Change Treatments

“…In B. nana leafs on unfertilized plots were found to have following leaf trait measures: leaf area = 0.98 ± 0.02, SLA = 133.3 ± 2.1, LDMC = 0.55 ± 0.01, leaf nitrogen concentration (LNC) = 24.2 ± 0.5, leaf phosphorus concentration (LPC) = 2.05 ± 0.08, and S. pulchra leafs on unfertilized plots were found to have following measures: leaf area = 3.20 ± 0.14, SLA = 122.5 ± 2.5, LDMC = 0.50 ± 0.01, LNC = 16.6 ± 0.6, LPC = 1.57 ± 0.12 (Iturrate‐Garcia et al., 2020). While the SLA values for B. nana were in the typical trait range compared to the global values of this species, LDMC values were in the upper part of the global range (Kemppinen & Niittynen, 2022).…”