Abstract
Understanding plant resource use efficiencies (RUEs) and their tradeoffs in a desert shrub community, particularly as it concerns the usage of water, light, and nitrogen, remains an ecological imperative. Plant RUEs have been widely used as indicators to understand plant acclimation processes to unfavorable environmental conditions. This study aimed to examine seasonal dynamics in RUEs in two widely distributed plant species in a typical desert shrub community (i.e., Artemisia ordosica and Leymus secalinus) based on in-situ measurements of leaf photosynthesis, specific leaf area (SLA), leaf nitrogen concentration (i.e., Nmass + Narea), and several site-related abiotic factors. Both species exhibited significant seasonal variation in RUEs, with a coefficient of variation (CV) >30% and seasonal divergence among the various RUEs. Seasonal divergence was largely controlled by variation in stomatal conductance (Gs), which was in turn influenced by variation in soil water content (SWC) and water vapor pressure deficit (VPD). RUEs between species converged, being positively correlated, yielding: (i) r2 = 0.40 and p < 0.01 for WUE; (ii) r2 = 0.18 and p < 0.01 for LUE; and (iii) r2 = 0.25 and p < 0.01 for NUE. RUEs for A. ordosica were mostly larger than those for L. secalinus, but less reactive to drought. This suggests A. ordosica was more conservative in its usage of available resources and was, therefore, better able to adapt to arid conditions. Resource use strategies between species differed in response to drought. Desert shrubs are projected to eventually replace grasses, as drought severity and duration increase with sustained regional climate change.
Highlights
Drylands cover 39% of the earth’s land surface and are home to about 20% of the world’s human population [1]
Light use efficiency peaked at different months of the growing season for the two species, i.e., LUE being maximum in spring for A. ordosica, with a value of 0.033 mol mol− 1, and in summer for L. secalinus, with a value of 0.016 mol mol− 1 (Figure 6B)
The results indicated that dominant species have adaptive differentiation of resource use-related traits to achieve local coexistence in dryland ecosystems
Summary
Drylands (arid and semiarid areas) cover 39% of the earth’s land surface and are home to about 20% of the world’s human population [1]. It is expected that there will be changes in the supply of available plant resources, such as water (W), light (L), and nitrogen (N) for photosynthetic assimilation, as well as for the maintenance of functional plant structures. This may lead to changes in plant resource use efficiencies (i.e., RUEs, or individually through WUE, LUE, and NUE). To better model plant responses to climate change in arid and semiarid areas, relative changes (tradeoffs) among WUE, LUE, and NUE and their causes need to be quantified.
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