 |
| Titel |
Large regional-scale variation in C3/C4 distribution pattern of Inner Mongolia steppe is revealed by grazer wool carbon isotope composition |
| VerfasserIn |
K. Auerswald, M. H. O. M. Wittmer, T. T. Männel, Y. F. Bai, R. Schäufele, H. Schnyder |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1726-4170
|
| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 6, no. 5 ; Nr. 6, no. 5 (2009-05-11), S.795-805 |
| Datensatznummer |
250003743
|
| Publikation (Nr.) |
 copernicus.org/bg-6-795-2009.pdf |
|
|
|
|
|
| Zusammenfassung |
| This work explored the spatial variation of C3/C4 distribution in the Inner
Mongolia, P. R. China, steppe by geostatistical analysis of carbon isotope
data of vegetation and sheep wool. Standing community biomass (n=118) and
sheep wool (n=146) were sampled in a ~0.2 Mio km2 area. Samples
from ten consecutive years (1998–2007) were obtained. Community biomass
samples represented the carbon isotopic composition of standing vegetation
on about 1000 m2 ("community-scale"), whereas the spatio-temporal scale
of wool reflected the isotope composition of the entire area grazed by the
herd during a 1-yr period (~5–10 km2, "farm-scale"). Pair wise
sampling of wool and vegetation revealed a 13C-enrichment of 2.7±0.7‰ (95%
confidence interval) in wool relative to vegetation, but this
shift exhibited no apparent relationships with environmental parameters or
stocking rate. The proportion of C4 plants in above-ground biomass
(PC4, %) was estimated with a two-member mixing model of 13C
discrimination by C3 and C4 vegetation (13Δ3 and
13Δ4, respectively), in accounting for the effects of
changing 13C in atmospheric CO2 on sample isotope composition, and
of altitude and aridity on 13Δ3. PC4 averaged 19%,
but the variation was enormous: full-scale (0% to 100%) at
community-scale, and 0% to 85% at farm-scale. The farm-scale variation
of PC4 exhibited a clear regional pattern over a range of ~250
km. Importantly PC4 was significantly higher above the 22°C
isotherm of the warmest month, which was obtained from annual
high-resolution maps and averaged over the different sampling years. This is
consistent with predictions from C3/C4 crossover temperature of quantum
yield or light use efficiency in C3 and C4 plants. Still, temperature
gradients accounted for only 10% of the farm-scale variation of PC4,
indicating that additional factors control PC4 on this scale. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|