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

Abstract

AbstractQuestionsMany 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).LocationUtqiaġvik, Atqasuk, and Toolik Lake, Alaska.MethodsThis 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.ResultsComparison 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.ConclusionsBecause 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.