Fig 1.
Sampling sites in Damxung County, Tibetan Plateau.
This figure is a modification from the Vegetation Map of The People’s Republic of China (1:1000000) [38].
Fig 2.
Carbon isotopic composition of wool (δ13Cwool) from Tibetan alpine meadows and of atmospheric CO2 (δ13Cair, δ13Cair_Waliguan).
The wool data were fitted with a linear model (y = –0.028x + 32.561, n = 106, P < 0.001).
Fig 3.
Ecophysiological parameters of Tibetan alpine meadows reconstructed from the δ13C time series of wool samples.
(A) Carbon isotope discrimination (13Δveg); (B) CO2 concentration in the atmosphere (Ca, dashed line) and in intercellular space (Ci, solid line); (C) the difference between Ca and Ci (Ca−Ci). The parameter trend lines were calculated using the values derived from δ13C of wool samples (n = 106). The models fitting Ci and Ca−Ci data were y = 0.029e0.004x and y = 0.009e0.005x respectively.
Fig 4.
Ecophysiological parameters of Tibetan alpine meadows.
(A) Intrinsic water use efficiency (Wi), n = 106; (B) atmospheric vapor pressure deficit (VPD), n = 49; (C) effective water use efficiency (We), n = 106. The parameter trend lines were calculated using values derived from δ13C of wool samples.
Table 1.
Long-term changes in intrinsic water use efficiency (Wi) of trees and alpine meadow and in atmospheric CO2 concentration (Ca).