Leaf δ¹³C reflects ecosystem patterns and responses of alpine plants to the environments on the Tibetan Plateau

Abstract

Leaf δ13C is an indicator of water‐use efficiency and provides useful information on the carbon and water balance of plants over longer periods. Variation in leaf δ13C between or within species is determined by plant physiological characteristics and environmental factors. We hypothesized that variation in leaf δ13C values among dominant species reflected ecosystem patterns controlled by large‐scale environmental gradients, and that within‐species variation indicates plant adaptability to environmental conditions. To test these hypotheses, we collected leaves of dominant species from six ecosystems across a horizontal vegetation transect on the Tibetan Plateau, as well as leaves of Kobresia pygmaea (herbaceous) throughout its distribution and leaves of two coniferous tree species (Picea crassifolia, Abies fabri) along an elevation gradient throughout their distribution in the Qilian Mountains and Gongga Mountains, respectively. Leaf δ13C of dominant species in the six ecosystems differed significantly, with values for evergreen coniferous<evergreen broadleaved tree<alpine shrub<sedges∼graminoid<xeromorphs. Leaf δ13C values of the dominant species and of K. pygmaea were negatively correlated with annual precipitation along a water gradient, but leaf δ13C of A. fabri was not significantly correlated with precipitation in habitats without water‐stress. This confirms that variation of δ13C between or within species reflects plant responses to environmental conditions. Leaf δ13C of the dominant species also reflected water patterns on the Tibetan Plateau, providing evidence that precipitation plays a primary role in controlling ecosystem changes from southeast to northwest on the Tibetan Plateau.

Succession of plant community composition and leaf functional traits in responding to karst rocky desertification in the Wushan County in Chongqing, China

“…Additionally, high LDMC is especially beneficial in drought due to the optimal water use efficiency (Song et al 2008). Soils in SKRD regions have higher SBD, which indicates higher water permeability, thus weaker water retention ability.…”

Soil n‐alkane δ13C along a mountain slope as an integrator of altitude effect on plant species δ13C

“…Above the threshold, additional precipitation has little impact on leaf d 13 C [Leffler and Evans, 1999;Leffler and Enquist, 2002;Song et al, 2008]. The global pattern of plant species-level d 13 C increase with altitude is established from humid areas avoiding drought stress, and hence above this precipitation threshold, reflecting the response of gas exchange physiology to altitude, i.e., reducing stomatal conductance and decreasing the ratio of internal to external CO 2 concentrations (c i /c a ) due to the decreasing temperature and atmospheric partial pressure of CO 2 and O 2 with altitude [e.g., Körner et al, 1991;Kelly and Woodward, 1995].…”

“…The global pattern of plant species-level d 13 C increase with altitude is established from humid areas avoiding drought stress, and hence above this precipitation threshold, reflecting the response of gas exchange physiology to altitude, i.e., reducing stomatal conductance and decreasing the ratio of internal to external CO 2 concentrations (c i /c a ) due to the decreasing temperature and atmospheric partial pressure of CO 2 and O 2 with altitude [e.g., Körner et al, 1991;Kelly and Woodward, 1995]. However, below the precipitation threshold, a negative correlation occurs between total annual precipitation and plant d 13 C, suggesting that precipitation is an important factor influencing plant physiology [Leffler and Evans, 1999;Leffler and Enquist, 2002;Van de Water et al, 2002;Song et al, 2008], i.e., a reduction in stomatal conductance and leaf c i /c a as soil moisture declined. Both scenarios likely occur along the eastern slope of Mt.…”

Driving forces of mid-Holocene vegetation shifts on the upper Tibetan Plateau, with emphasis on changes in atmospheric CO2 concentrations

“…Characteristic elements of early-Holocene steppes (Artemisia, Ephedra) that today dominate the relatively dry north-eastern and north-central Plateau, are well adapted to water limitation as indicated by their high water-use efficiency (i.e. the ratio of carbon gained to water lost in leaf gas exchange), morphology, and chemical leaf traits compared to mesic Kobresia-meadows that today occupy comparatively mesic areas on the eastern and southern Plateau (Pyankov and Kondrachuk, 2003;Song et al, 2008). Quantitative moisture-balance reconstructions from Koucha Lake and Xuguo Lake (Fig.…”