Carbon isotope discrimination of C3 vegetation in Central Asian Grassland as related to long-term and short-term precipitation patterns

Abstract

The relationship between carbon isotope discrimination ( 13 ) of C3 vegetation and long-term (30 years) and short-term (growing period) precipitation was investigated. Different species of Stipa, a dominant grass genus in the (semi-)arid Asian steppes, and other C3 species were collected along aridity gradients in Inner Mongolia in 2005 (11 sites, 71 samples) and in the Republic of Mongolia in 2006 (40 sites, 45 samples). The data set was expanded with published and unpublished data of Stipa and other C3 species (11 studies covering 8 years, including 64 observations of Stipa, and 103 observations of other C3 species) and C3 community bulk-samples (11 samples). Weather data were geostatistically interpolated for all sampling sites and years. 13 of Stipa followed different relationships for the individual years when related to mean annual precipitation due to large anomalies between annual and long-term average precipitation patterns. However, the 13 response to rainfall converged when the (long-term) mean annual precipitation was replaced by year-specific mean daily precipitation during the growing period (P G ). Remarkably, the 13 -response to (P G ) for C3 species as a whole (including herbaceous dicots, semi-shrubs and grasses) and also the C3 communitylevel response were virtually identical to that of Stipa. The relation was also valid outside the geographical and climatic range where it was developed, giving proof of its robustness.

Relationships between C3 Plant Foliar Carbon Isotope Composition and Element Contents of Grassland Species at High Altitudes on the Qinghai-Tibet Plateau, China

“…However, Wittmer et al [53] found that there was no relationship between foliar δ 13 C and foliar C/N. Our findings suggest that plants on the Qinghai-Tibet Plateau that have higher WUE may also have higher NUE, and on the basis of the significant correlation between δ 13 C and C/P for all samples and Stipa (Table 3), also have higher phosphorus use efficiency (PUE).…”

Sheep Wool δ13C Reveals No Effect of Grazing on the C3/C4 Ratio of Vegetation in the Inner Mongolia–Mongolia Border Region Grasslands

“…13Δc was calculated as 13Δwool +3.2‰, the constant fractionation between vegetation and wool [14]. Site-specific 13Δ3 was estimated from year-specific growing-season precipitation, PG in mm d−1, according to [24] and altitude, A in m above sea level, according to [25] asand 13Δ4 was taken as a constant 7.2‰ from [12]. The relatively high 13Δ4 is mainly caused by C. squarrosa, which dominates the C4 community and which has a high leakiness affecting 13Δ [26].…”

Variation in carbon isotope discrimination in Cleistogenes squarrosa (Trin.) Keng: patterns and drivers at tiller, local, catchment, and regional scales

“…Growing season precipitation was geostatistically determined according to Wittmer et al (2008) for each sampling location and time of sampling. This was done by interpolating between meteorological stations and taking into account 1.5×1.5 km 2 resolution maps of MAP, mean monthly precipitation, MJulT, and MAT (Climate Source, Inc., Corvallis, OR, USA).…”

“…Carbon isotope composition and nitrogen content were then measured using an elemental analyser (NA 1110; Carlo Erba, Milan, Italy) interfaced (ConFlo III; Finnigan MAT, Bremen, Germany) to an isotope ratio mass spectrometer (Delta Plus; Finnigan MAT) following the protocol by Wittmer et al (2008). Carbon isotope data were specified as δ 13 C relative to the Vienna Pee Dee Belemnite standard:…”

“…This approach is based on the difference in discrimination against the heavy carbon stable isotope ( 13 Δ) during photosynthesis between C 3 and C 4 plants (Farquhar et al , 1989). A single mean C 4 end-member value is usually assumed in the two-member mixing model (Murphy and Bowman, 2007; Wittmer et al , 2010), whereas variable C 3 end-member values are estimated, based on the well known correlations between the 13 Δ of C 3 plants and environmental conditions (Mole et al , 1994; Männel et al , 2007; Wittmer et al , 2008). The reason for this is that 13 Δ of C 4 plants is reported to be less responsive to environmental variables than that of C 3 plants (Van de Water et al , 2002; Murphy and Bowman, 2009).…”