Limiting resource and leaf functional traits jointly determine distribution patterns of leaf intrinsic water use efficiency along aridity gradients

Abstract

Intrinsic water use efficiency (iWUE) is a critical eco-physiological function allowing plants to adapt to water- and nutrient-limited habitats in arid and semi-arid regions. However, the distribution of iWUE in coexisting species along aridity gradients and its controlling factors are unknown. We established two transects along an aridity gradient in the grasslands of Losses Plateau (LP) and Inner Mongolia Plateau (MP) to elucidate the patterns and underlying mechanisms of iWUE distribution in coexisting species along aridity gradient. We determined leaf carbon (δ13C) and oxygen (δ18O) stable isotopes, functional traits related to carbon fixation, and limiting resources. Bulk leaf δ13C and δ18O were used as proxies for time-integrated iWUE and stomatal conductance (gs) during the growing season. Our results showed that variability in iWUE within transect was primarily controlled by species, sampling sites and an interactive effect between species and sampling sites. Mean values of iWUE (iWUEMean) increased and coefficient of variation (CV) in iWUE (iWUECV) decreased with an increase in aridity, demonstrating that increases in aridity lead to conservative and convergent water use strategies. Patterns of iWUEMean and iWUECV were controlled primarily by the ratio of soil organic carbon to total nitrogen in LP and soil moisture in MP. This revealed that the most limited resource drove the distribution patterns of iWUE along aridity gradients. Interspecific variation in iWUE within transect was positively correlated with Δ18O, indicating that interspecific variation in iWUE was primarily regulated by gs. Furthermore, relationship between iWUE and multi-dimensional functional trait spectrum indicated that species evolved species-specific strategies to adapt to a harsh habitat by partitioning limiting resources. Overall, these findings highlighted the interactive effects of limiting resources and leaf functional traits on plant adaptation strategies for iWUE, and emphasized the importance of considering biological processes in dissecting the underlying mechanisms of plant adaptation strategies at large regional scales.

Two Congeneric Shrubs from the Atacama Desert Show Different Physiological Strategies That Improve Water Use Efficiency under a Simulated Heat Wave

“…Environmental gradients shape the expression of ecophysiological traits [54,55]. Our results can be associated with the local environmental conditions within the species' altitudinal distribution.…”

Leaf Traits Explain the Growth Variation and Nitrogen Response of Eucalyptus urophylla × Eucalyptus grandis and Dalbergia odorifera in Mixed Culture

“…These traits were significantly promoted by mixed culture and N application, thereby promoting the height, ground diameter, branching, and biomass of E. urophylla × E. grandis (Figure 8A). Leaf morphological traits have been reported to be related to plant adaptation to environmental changes [40,46]. In this study, the LMF was found to be significantly negatively correlated with the growth indices and biomass of E. urophylla × E. grandis (Figure 8A).…”

“…An important reason is that the increase in leaf N promotes chlorophyll synthesis (Figure 8A) and improves light use efficiency [58,59]. Second, the increase in Pn benefited from the increase in CE (Figure 5), which improved the CO 2 conversion efficiency [44,46]. In addition, N addition may indirectly improve photosynthetic efficiency by improving leaf stomatal permeability (gs), WUE, and photoprotective capacity (by Car) [60][61][62].…”

“…Based on this information, this study used controlled pot experiments of Eucalyptus urophylla × eucalyptus grandis (E. urophylla × E. grandis) and Dalbergia odorifera (D. odorifera) to investigate the effects of mixed cultivation, N addition, and co-treatments on leaf functional traits as well as further on the growth and biomass of seedlings. In this study, leaf morphological/structural, physiological, and chemical traits related to plant growth and development were collected according to previous methods (Table S1) [39][40][41][42][43][44][45][46]. The objectives of this research were (1) to understand the adaptive mechanisms of leaf traits in E. urophylla × E. grandis and D. odorifera in response to mixed cultivation and N application, (2) to test the hypothesis that mixed plantation and N application and their cotreatments promote the growth and development of E. urophylla × E. grandis and D. odorifera, and (3) to elucidate the correlation between key leaf traits and the growth of E. urophylla × E. grandis and D. odorifera, as well as their respective regulatory pathways.…”

Climate anomalies and neighbourhood crowding interact in shaping tree growth in old‐growth and selectively logged tropical forests

“…A promising way forward is to integrate leaf traits that directly link to plant carbon‐water relations or physiological responses to heat and water stress (Anderegg et al., 2018; Barros et al., 2019; McGregor et al., 2021; Powell et al., 2017; Powers et al., 2020; Rowland et al., 2021; Serra‐Maluquer et al., 2022; see Table 1). For instance, stomatal density (Drake et al., 2013; Machado et al., 2021) and oxygen and carbon isotope composition (Farquhar et al., 1989, 2007; Moreno‐Gutiérrez et al., 2012) can determine trade‐offs between carbon assimilation and water loss at the leaf level under water‐limited conditions (Guerrieri et al., 2019; Prieto et al., 2018; Scheidegger et al., 2000; Wang & Wen, 2022b). Leaf water potential at turgor loss point is linked to species abilities to maintain key plant functions and growth during drought (Bartlett et al., 2016; Bartlett, Scoffoni, & Sack, 2012; Maréchaux et al., 2018).…”