Dynamic Changes in Plant Resource Use Efficiencies and Their Primary Influence Mechanisms in a Typical Desert Shrub Community

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.

Improved Tolerance of Artemisia ordosica to Drought Stress via Dark Septate Endophyte (DSE) Symbiosis

“…Despite the harsh conditions, desert ecosystems often comprise multizonal vegetation, and species that have typical characteristic of adaptation to drought, which is the main property determining desert productivity [ 9 , 27 ]. Among these species, Artemisia ordosica is one of the most dominant subshrubs and is distributed widely in the sandy areas of northwest China, such as Inner Mongolia, Ningxia, Shaanxi, Gansu, and other provinces [ 28 , 29 , 30 ]. Artemisia ordosica can adapt well to water stress conditions and has developed the typical morphological and physiological characteristics of adaptation to drought and sand burial [ 29 , 31 ].…”

“…Among these species, Artemisia ordosica is one of the most dominant subshrubs and is distributed widely in the sandy areas of northwest China, such as Inner Mongolia, Ningxia, Shaanxi, Gansu, and other provinces [ 28 , 29 , 30 ]. Artemisia ordosica can adapt well to water stress conditions and has developed the typical morphological and physiological characteristics of adaptation to drought and sand burial [ 29 , 31 ]. For example, it has a taproot system, consisting of one large vertical root that produces many small lateral roots in a well-developed system.…”

Water use strategies of Nitraria tangutorum in the lake-basin region of the Badain Jaran Desert

“…Examples of these changes include smaller and thicker leaves, smaller specific leaf area, and higher leaf nitrogen content, thus achieving higher photosynthesis rates while reducing the evaporative area of a single leaf ( Wang et al., 2017 ); development of longer fine roots, increased specific root length, and decreased water consumption ( Li et al., 2023 ); and control of stomatal openness ( Graham and Zhang, 2014 ), among others. As drought progresses, some plants display greater stomatal conductance variation, resulting in an increased plant WUE ( Lázaro-Nogal et al., 2013 ; Jiang et al., 2021 ). Some species obtain high carbon assimilation rates and maintain high WUE by reducing water loss through reduced stomatal conductance ( Yang et al., 2018 ).…”

The Physiological Adjustments of Two Xerophytic Shrubs to Long-Term Summer Drought

“…In environments where light is not a limiting resource, such as in shrublands and grasslands [11,12], water and available soil nutrients, particularly N, are viewed as the main constraints on plant C fixation in drylands [13][14][15]. Instantaneous water use efficiency (IWUE), defined as the ratio of plant net photosynthesis to transpiration, reflects the interaction between C gains and water consumption [16,17].…”

“…E. multiflora is known to increase its IWUE to reduce water losses during mild drought and decrease its IWUE during severe drought [9]. These studies have emphasized that there is not always a single suite of tradeoffs between use efficiencies of constraining and non-constraining resources [12,23]. Together, the impact of long-term drought on RUEs may be very different than what would be recorded over the short term.…”