Stem Trait Spectra Underpin Multiple Functions of Temperate Tree Species

Abstract

A central paradigm in comparative ecology is that species sort out along a slow-fast resource economy spectrum of plant strategies, but this has been rarely tested for a comprehensive set of stem traits and compartments. We tested how stem traits vary across wood and bark of temperate tree species, whether a slow-fast strategy spectrum exists, and what traits make up this plant strategy spectrum. For 14 temperate tree species, 20 anatomical, chemical, and morphological traits belonging to six key stem functions were measured for three stem compartments (inner wood, outer wood, and bark). The trait variation was explained by major taxa (38%), stem compartments (24%), and species within major taxa (19%). A continuous plant strategy gradient was found across and within taxa, running from hydraulic safe gymnosperms to conductive angiosperms. Both groups showed a second strategy gradient related to chemical defense. Gymnosperms strongly converged in their trait strategies because of their uniform tracheids. Angiosperms strongly diverged because of their different vessel arrangement and tissue types. The bark had higher concentrations of nutrients and phenolics whereas the wood had stronger physical defense. The gymnosperms have a conservative strategy associated with strong hydraulic safety and physical defense, and a narrow, specialized range of trait values, which allow them to grow well in drier and unproductive habitats. The angiosperm species show a wider trait variation in all stem compartments, which makes them successful in marginal- and in mesic, productive habitats. The associations between multiple wood and bark traits collectively define a slow-fast stem strategy spectrum as is seen also for each stem compartment.

Drought resilience of conifer species is driven by leaf lifespan but not by hydraulic traits

“…The trade‐off between hydraulic and biomechanical safety and efficiency has been frequently found in Mediterranean (Quero et al ., 2011; Ramírez‐Valiente et al ., 2020), tropical and temperate forests or tree species (Hacke et al ., 2006; van der Sande et al ., 2019; López et al ., 2021), whereas the trade‐offs across areas of temperate conifer species are rarely reported, or no such a trade‐off has been found within species (López et al ., 2013; Rosas et al ., 2019). Hence, our study supports the evidence that such a safety–efficiency spectrum is not only found across angiosperms and gymnosperms, where gymnosperms occupy the safe end of angiosperms and gymnosperms (Yang et al ., 2022), but also within gymnosperm species. We conclude that the hydraulics spectrum exists in different forest ecosystems, enabling species to adapt to divergent environments for their water use strategy in a changing climate.…”

“…This global spectrum is well established for leaves (i.e. the leaf economics spectrum (LES)) (Wright et al ., 2004), but developed to a lesser extent for stems (Yang et al ., 2022).…”

Water taken up through the bark is detected in the transpiration stream in intact upper‐canopy branches

“…To test for the impacts of cold temperatures on bark water uptake, we conducted the same experiment in a temperate forest in Northern Spain the following winter, on the same study species ( P. sylvestris ). Finally, species vary greatly both in hydraulic wood traits and bark functional traits (Johnson et al, 2012; Rosell et al, 2014), particularly between angiosperms and gymnosperms (Yang et al, 2022), yet previous studies on bark water uptake have focused exclusively on gymnosperms (with the exception of Liu et al, 2019; performed under artificial laboratory conditions). Here, we tested for bark water uptake in an evergreen conifer ( P. sylvestris ) and in a broadleaved deciduous angiosperm ( Fagus sylvatica ), growing in the same temperate forest in Spain.…”

Stem traits, compartments and tree species affect fungal communities on decaying wood

“…Sawdust from inner wood, outer wood and bark was collected separately, then the sawdust samples were ground in an MM400 ball mill (Retsch) and used for measurements of pH, C/N, C/P, N/P ratios, lignin concentration, nitrogen (N) and phosphorus (P) concentrations. Sampling and measurements are described in detail in Yang et al (2022).…”