Functional correlations between specific leaf area and specific root length along a regional environmental gradient in Inner Mongolia grasslands

Abstract

Summary Among above‐ and below‐ground traits, specific leaf area (SLA, cm2 g−1) and specific root length (SRL, m g−1) are the two key traits reflecting species resource acquisition strategies. However, patterns of variation in SLA and SRL have rarely been examined simultaneously across evolutionary history and environmental gradients, and the SLA–SRL relationship is still controversial on several grounds. We examined the inter‐ and intraspecific variations in SLA and SRL of different root branching orders and the SLA–SRL relationship across 55 species and 21 plant communities of four vegetation types along a 2000‐km transect in the Inner Mongolia grassland. With increasing root branching order, the interspecific variation in SRL increased, but the intraspecific variation in SRL decreased considerably, and the form of SLA–SRL relationship shifted from positive to negative. This indicates that acquisition of soil resources (e.g. water and nutrients) is a fundamental strategy for plant investment to root length. When inter‐ and intraspecific variations in SLA and SRLs were partitioned into alpha (within‐community) and beta (among‐community) components, the alpha component exhibited substantially greater inter‐ and intraspecific variations than the beta component. Across the transect, the evolutionarily late diverged species in phylogenetic tree evolved towards low SLA and SRL‐1 (SRL for first‐order roots) and tended to distribute in resource‐poor conditions along the environmental gradient. The early diverged species, in contrast, had high SLA and SRL‐1 and mostly distributed in resource‐rich conditions. Our findings suggest that patterns of inter‐ and intraspecific variations in SLA and SRL of different root branching orders and the form of SLA–SRL relationship could be well explained by within‐ and among‐community filtering processes and species divergence time. Coordination and trade‐offs between leaves and roots do not mutually exclude but operate simultaneously at different scales and among different root branching orders in arid and semi‐arid grasslands.

Relationships between plant traits, soil properties and carbon fluxes differ between monocultures and mixed communities in temperate grassland

“…For example, de Vries et al () observed CWM SLA to vary from 17.6 to 35.1 mm 2 /mg for a range of grassland types across England, while Grigulis et al () recorded a range in CWM SLA from 5 to 25 mm 2 /mg across montane grasslands in three geographically distinct locations in Europe. Furthermore, across a 2000‐km regional transect in Inner Mongolia, Cheng, Chu, Chen, Bai, and Niu () measured a breadth of variation in CWM SRL from 1 to 91 m/g. As such, the gradients of trait variation in our field communities were reasonably representative of those found in other studies at much larger scales, thereby enabling us to test our hypotheses on links between above‐ and below‐ground traits, soil properties and ecosystem C fluxes.…”

Shifts in plant functional strategies over the course of wheat domestication

“…Wild ancestors displayed more correlations, particularly between root and leaf traits, than the domesticated forms. This result suggests that domestication and breeding may have consciously or unconsciously decoupled the different aspects of resource capture and use in modern varieties (Cheng, Chu, Chen, & Bai, ; Geng, Wang, Jin, Liu, & He, ). On the contrary, plant height, which was not related to the global strategy of the wild ancestor, was related to traits from the leaf economics spectrum and biomass production, from the first step of the domestication ( T. turgidum ssp.…”

The response of root traits to precipitation change of herbaceous species in temperate steppes

“…The typical steppe, located at the middle part of the transect (sites 4–7), is dominated by Stipa grandis , L. chinensis and C. squarrosa . The desert steppe, located at the west part of the transect (sites 8–10), is dominated by S. krylovii , Cleistogenes songorica , S tipa breviflora , Zygophyllum gobicum , Halogetong lomeratus and Agropyron desertorum (Cheng, Chu, Chen, & Bai, ). Following a simple vegetation survey (Table S3), two regionally common species, grass L. chinensis and forb A. frigida , were selected to explore the intraspecific variation of root traits along the precipitation gradients.…”