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

• Published in: Journal of vegetation science Vol. 32; no. 3
• Main Authors: Betway, Katlyn R., Hollister, Robert D., May, Jeremy L., Oberbauer, Steven F., Botta‐Dukát, Zoltán
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc 01.05.2021
• Subjects: arctic; Climate change; Dry matter; Environmental conditions; Environmental gradient; growth form; Herbivores; International Tundra Experiment; intraspecific variation; Leaf area; Leaves; Normalized difference vegetative index; Partitioning; Plants; Polar environments; Shrubs; Species; tundra; Variability; Variance analysis; variance partitioning; Variation; Vegetation; Vegetation index; United States > US; Alaska
• ISSN: 1100-9233; 1654-1103
• DOI: 10.1111/jvs.13040

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. Arctic plants showed considerable variability in functional traits among populations spanning a latitudinal gradient, with strong individualistic trends even for species within the same growth form. In general, plants were taller, had greater leaf area, and thinner leaves in the southern populations. Functional traits also exhibited differences in variance partitioning, with each trait displaying different levels of ITV.