Root trait variation along a sub‐arctic tundra elevational gradient

Abstract

Elevational gradients are useful for predicting how plant communities respond to global warming, because communities at lower elevations experience warmer temperatures. Fine root traits and root trait variation could play an important role in determining plant community responses to warming in cold-climate ecosystems where a large proportion of plant biomass is allocated belowground. Here, we investigated the effects of elevation-associated temperature change on twelve chemical and morphological fine root traits of plant species and plant communities in a Swedish subarctic tundra. We also assessed the relative contributions of plant species turnover and intraspecific variation to the total amount of community-level root trait variation explained by elevation. Several root traits, both at the species and whole community levels, had significant linear or quadratic relationships with elevation, but the direction and strength of these relationships varied among traits and plant species. Further, we found no support for a unidirectional change from more acquisitive root trait values at the lower elevations towards trait values associated with greater nutrient conservation at the higher elevations, either at the species or community level. On the other hand, root trait coefficients of variation at the community level increased with elevation for several root traits. Further, for a large proportion of the community-level traits we found that intraspecific variation was relatively more important than species turnover, meaning that trait plasticity is important for driving community-level trait responses to environmental factors in this tundra system. Our findings indicate that with progressing global warming, intraspecific trait variation may drive plant community composition but this may not necessarily lead to shifts in root resource-acquisition strategy for all species.

Special Issue: Root traits and functioning: from individual plants to ecosystems

“…1 would adjust (combinations of ) these traits whilst keeping the four key RES traits (root N, specific root length, root tissue density and root diameter) constant, it may remain at the same position at the RES, but still display considerable belowground adjustments in their belowground strategies. At the same time, which traits are being adjusted could be species-specific (Spitzer et al 2023), so that to conserve plant resources under environmental stress, Species 4 may enhance root diameter which in turn may enhance root lifespan (McCormack et al 2012) whereas Species 5 increases root tissue density, as assumed by the RES framework. Together, the studies in this Species Issue provide highly important clues for the further development of the RES by identifying relevant additional traits that characterize species, their resource strategies and coping mechanisms for environmental variation.…”

“…Such above–belowground decoupling may result from the different environmental factors that determine leaf disease development and belowground trait expressions (Gagliardi et al 2023). Along an abiotic (elevational) environmental gradient, the study by Spitzer et al (2023) on intraspecific variation in root traits across 16 tundra species highlights the variable ways through which different species alter a variety of root traits, or adjust the same root trait in different manners (both linearly and nonlinearly). This intraspecific trait variation (rather than species turnover) was also the main driver of root trait variation at the community level, in this study, emphasizing its importance for plant communities to cope with environmental change (Spitzer et al 2023).…”

Above‐ and belowground traits along a stress gradient: trade‐off or not?

“…These studies describe how belowground traits coordinate with aboveground ones to determine viable species ecological strategies, yet they do not provide information on community assembly mechanisms. At the same time, few efforts have been made to investigate how belowground traits contribute to plant community organization along stress gradient (Holdaway et al 2011, Spitzer et al 2022), and attempts to examine aboveground and belowground plant traits in a single framework are still rare.…”

Are absorptive root traits good predictors of ecosystem functioning? A test in a natural temperate forest

“…Intraspecific variation was found to contribute considerably to trait variation and can thus influence community composition and ecosystem processes (Messier et al ., 2010; Westerband et al ., 2021). Recent studies demonstrate that intraspecific rather than interspecific root trait variability plays an important role in driving plant root community responses to long‐term climatic changes (Spitzer et al ., 2022). In addition, this study only focused on the linear relations between traits and ecosystem functions without considering the potential nonlinear response, which may provide a better fit for the data.…”