Spatial and temporal characteristics of Neogene palynoflora in China and its implication for the spread of steppe vegetation

Jiang, Hanchao; Ding, Zhongli

doi:10.1016/j.jaridenv.2009.03.011

Cited by 43 publications

(24 citation statements)

References 46 publications

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“…Under the macrofossil dating hypothesis, without phytolith evidence, C 4 origins appear almost entirely after the Oligocene atmospheric CO 2 drop (with the possible exception of the Chloridoideae) [54], and almost all are within the time period in which C 3 grasslands are believed to have existed on various continents [55]–[62], [2], [63]. Under this younger dating scenario, C 4 photosynthesis may have evolved coincidently with movement into already established C 3 -dominated grasslands.…”

Section: Discussionmentioning

confidence: 98%

C4 Photosynthesis Promoted Species Diversification during the Miocene Grassland Expansion

2014

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Identifying how organismal attributes and environmental change affect lineage diversification is essential to our understanding of biodiversity. With the largest phylogeny yet compiled for grasses, we present an example of a key physiological innovation that promoted high diversification rates. C4 photosynthesis, a complex suite of traits that improves photosynthetic efficiency under conditions of drought, high temperatures, and low atmospheric CO2, has evolved repeatedly in one lineage of grasses and was consistently associated with elevated diversification rates. In most cases there was a significant lag time between the origin of the pathway and subsequent radiations, suggesting that the ‘C4 effect’ is complex and derives from the interplay of the C4 syndrome with other factors. We also identified comparable radiations occurring during the same time period in C3 Pooid grasses, a diverse, cold-adapted grassland lineage that has never evolved C4 photosynthesis. The mid to late Miocene was an especially important period of both C3 and C4 grass diversification, coincident with the global development of extensive, open biomes in both warm and cool climates. As is likely true for most “key innovations”, the C4 effect is context dependent and only relevant within a particular organismal background and when particular ecological opportunities became available.

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Section: Discussionmentioning

confidence: 98%

C4 Photosynthesis Promoted Species Diversification during the Miocene Grassland Expansion

2014

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“…Given that explaining the observed compositional variation requires a minimum number of end members in EMA [18], three end members were modeled in this study and their peak values concentrated at 1–10 μm (EM 1), 10–100 μm (EM 2), and more than 100 μm (EM 3), respectively (Fig 2B). Noticeably, the study area lies in the western CLP and remained arid to semi-arid during the Neogene period [21–22], which is supported by the spatial and temporal variations in Fupingopollenites percentages across Inner and East Asia [23]. Previous studies suggest that the clay mineral composition in loess and soil was of clastic origin [24] and that some clay-size material is formed in low energy aeolian environments [25] or mountain processes such as glacial grinding, frost weathering, salt weathering and even earthquakes [26–30], and thus variation in EM 1 reflected a background deposition of dust.…”

Section: End-member Modeling Of the Grain-size Recordmentioning

confidence: 99%

End-member modeling of the grain-size record of Sikouzi fine sediments in Ningxia (China) and implications for temperature control of Neogene evolution of East Asian winter monsoon

Jiang

Wan

et al. 2017

PLoS ONE

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The Late Cenozoic East Asian winter monsoon (EAWM) enhancement has been attributed to several factors, such as uplift of the Tibetan Plateau, retreat of the Paratethys Sea, and global cooling related to polar ice volume increment. However, the fundamental forcing factors remain enigmatic due to the absence of long and continuous climate records and sensitive indicators. Here we reanalyzed the published grain-size record of Sikouzi fine sediments in the western Chinese Loess Plateau through end-member (EM) modeling. The results indicate that EM 2 with grain-size peaks between 10–100 μm decreased in content from 20.1 to 17 Ma and stepwise increased from 17 to 0.07 Ma during the following six stages (17–15 Ma, 15–12 Ma, 12–8 Ma, 8–6 Ma, 6–4 Ma and 4–0 Ma). Such varying trends can be successively correlated in seven stages with the integrated benthic δ18O record, implying that global warming weakened the EAWM from 20.1 to 17 Ma and global cooling has stepwise strengthened the EAWM since 17 Ma. Therefore, we conclude that global temperature change played a major role on the evolution of EAWM during the Neogene period. By contrast, Late Cenozoic palaeogeographic reorganization caused by uplift of the Tibetan Plateau and retreat of the Paratethys Sea contributed less to the evolutionary evolution of EAWM. Spectral analysis of the EM 2 data first provided direct evidence of orbitally influenced deposition in the study area and thus the EAWM variations during the Neogene period. The 100-kyr period became weak since ~10 Ma, possibly due to the decrease in sensitivity of a more stable, continental-scale ice sheet in Antarctica to local insolation forcing, deserving further investigation.

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“…For instance, using aeolian and marine proxies, An et al (2001) divided the East Asian monsoon into three evolution stages of the Asian monsoon showing that the onset of the East Asian monsoon happened at about 9-8 Ma ago and the East Asian summer and winter monsoons intensified at about 3.6-2.6 Ma ago. However, by using Neogene pollen records, Jiang and Ding (2009) suggest that the East Asian summer monsoon was generally strong during the early to early middle Miocene and displayed a stepwise weakening since the late middle Miocene. Paleoclimatic reconstructions based on plant fossils provide opportunities to investigate the monsoon intensity quantitatively by using climatic variables.…”

Section: Introductionmentioning

confidence: 99%

Paleoclimatic estimation reveals a weak winter monsoon in southwestern China during the late Miocene: Evidence from plant macrofossils

Xing

Utescher

Jacques

et al. 2012

Palaeogeography, Palaeoclimatology, Palaeoecology

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Spatial and temporal characteristics of Neogene palynoflora in China and its implication for the spread of steppe vegetation

Cited by 43 publications

References 46 publications

C4 Photosynthesis Promoted Species Diversification during the Miocene Grassland Expansion

C4 Photosynthesis Promoted Species Diversification during the Miocene Grassland Expansion

End-member modeling of the grain-size record of Sikouzi fine sediments in Ningxia (China) and implications for temperature control of Neogene evolution of East Asian winter monsoon

Paleoclimatic estimation reveals a weak winter monsoon in southwestern China during the late Miocene: Evidence from plant macrofossils

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