Title: Summer
monsoon intensity controls C-4/C-3 plant abundance during the last 35
ka in the Chinese Loess Plateau: Carbon isotope evidence from bulk
organic matter and individual leaf waxes
Source: PALAEOGEOGRAPHY
PALAEOCLIMATOLOGY PALAEOECOLOGY 220 (3-4): 243-254 MAY 13 2005
Document Type: Article
Language: English
Abstract: The
natural abundance Of C-3 and C-4 plants is affected by multiple
environmental factors including temperature, moisture balance and
atmospheric pCO(2). The relative importance of these factors is a
subject of considerable debate, and may vary in different natural
ecosystems. Previous studies generally focus on single loess sequences
in the Chinese Loess Plateau, and conflicting conclusions on C-4/C-3
have been reached when studying carbon isotope ratios in carbonate and
organic matter. In this paper we report a comprehensive carbon isotopic
characterization of total organic carbon (TOC) and individual higher
plant leaf waxes from five loess sequences spanning the last 35 ka from
the Chinese Loess Plateau (CLP). The five coring sites encompass large
gradients of annual mean temperature (9.2-13.9 degrees C) and
precipitation (402-673 mm), allowing us to assess the controlling
mechanisms on C-4/C-3 plant ratios. Glacial-interglacial sequences
provide carbon isotope data for comparison with other climatic and
environmental proxies such as lithology and magnetic susceptibility.
Our results demonstrate that increased C4/C3 ratios are positively
correlated with higher temperature and increased summer rainfall which
characterize stronger summer monsoon in all five sites. We conclude C-4
abundance increases from the last glacial to the Holocene in response
to greater monsoon activity and that the C-4 expression is suppressed
in the cold and drier intervals. (c) 2005 Elsevier B.V. All rights
reserved.
Author Keywords: carbon
isotopes; loess-paleosol; paleovegetation; paleoclimate
KeyWords Plus: MAGNETIC-SUSCEPTIBILITY
SIGNAL; LATE MIOCENE; FUNCTIONAL TYPES; LATE QUATERNARY; CENTRAL TEXAS;
C-4 GRASSES; CLIMATE; VEGETATION; DELTA-C-13; EXPANSION
Addresses: Liu
WG (reprint author), Chinese Acad Sci, Inst Earth Environm, Xian,
710075 Peoples R China
CAS, IEE, State Key Lab Loess & Quaternary Geol, Xian, 710075
Peoples R China
Brown Univ, Dept Geol Sci, Providence, RI 02906 USA
Publisher: ELSEVIER
SCIENCE BV, PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS
Subject Category: GEOGRAPHY,
PHYSICAL; GEOSCIENCES, MULTIDISCIPLINARY; PALEONTOLOGY
IDS Number: 926ZR
ISSN: 0031-0182
