14 results on '"Fa-hu Chen"'
Search Results
2. Variation in the stable carbon and nitrogen isotope composition of plants and soil along a precipitation gradient in northern China.
- Author
-
Jian-Ying Ma, Wei Sun, Xiao-Ning Liu, and Fa-Hu Chen
- Subjects
Medicine ,Science - Abstract
Water availability is the most influential factor affecting plant carbon (δ(13)C) and nitrogen (δ(15)N) isotope composition in arid and semi-arid environments. However, there are potential differences among locations and/or species in the sensitivity of plant δ(13)C and δ(15)N to variation in precipitation, which are important for using stable isotope signatures to extract paleo-vegetation and paleo-climate information. We measured δ(13)C and δ(15)N of plant and soil organic matter (SOM) samples collected from 64 locations across a precipitation gradient with an isotherm in northern China. δ(13)C and δ(15)N for both C(3) and C(4) plants decreased significantly with increasing mean annual precipitation (MAP). The sensitivity of δ(13)C to MAP in C(3) plants (-0.6 ± 0.07‰/100 mm) was twice as high as that in C(4) plants (-0.3 ± 0.08‰/100 mm). Species differences in the sensitivity of plant δ(13)C and δ(15)N to MAP were not observed among three main dominant plants. SOM became depleted in (13)C with increasing MAP, while no significant correlations existed between δ(15)N of SOM and MAP. We conclude that water availability is the primary environmental factor controlling the variability of plant δ(13)C and δ(15)N and soil δ(13)C in the studied arid and semi-arid regions. Carbon isotope composition is useful for tracing environmental precipitation changes. Plant nitrogen isotope composition can reflect relative openness of ecosystem nitrogen cycling.
- Published
- 2012
- Full Text
- View/download PDF
3. An inverse relationship between moisture and grazing intensity in an arid mountain-basin system
- Author
-
Jun Zhang, Xiao-zhong Huang, Jia-le Wang, Richard HW Bradshaw, Tao Wang, Li-xiong Xiang, De-rui Luo, Zong-li Wang, and Fa-hu Chen
- Subjects
Geography, Planning and Development ,Earth and Planetary Sciences (miscellaneous) ,General Earth and Planetary Sciences - Abstract
Precipitation has been suggested as a crucial influencing factor in the primary productivity in arid and semi-arid regions, yet how moisture fluctuation in an arid mountain-basin system of the north Qinghai–Tibetan Plateau has affected human activities is poorly understood. Here, we reconstruct the variations of grazing intensity in high elevations and regional humidity based on independent and high-resolution records of Sporormiella-type coprophilous fungal spores and pollen grains in the same well-dated sediment core from Lake Tian’E in the western Qilian Mountains over the past 3500 years. We find that stronger grazing activity was associated with low regional effective moisture, and propose that the drier regional climate pushed people and their livestock into the mountainous areas. A notable exception was a reduction of human and grazing activities in arid region with high mountains during 380–580 CE caused by centennial-length dry and cold conditions. In addition, it is also noteworthy that intensified grazing activity occurred during 580–720 CE and after ∼1920 CE, corresponding to a warmer and wetter climate and diverse subsistence strategies with social developments in the lowlands of the Hexi Corridor. Our findings potentially provide a historical reference for understanding how ancient people adapted to the climate change in arid region with high mountains.
- Published
- 2021
4. [Untitled]
- Author
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Fa-Hu Chen, Qi Shi, and Jian-Min Wang
- Subjects
Hydrology ,education.field_of_study ,Population ,Climate change ,Aquatic Science ,Structural basin ,Arid ,law.invention ,law ,Aeolian processes ,Glacial period ,Radiocarbon dating ,education ,Geology ,Holocene ,Earth-Surface Processes - Abstract
In this study, a 6 m long core (16,000 BP) at the center of the dry Lake Yiema, a closed lake of Shiyang River drainage in Minqin Basin of the arid northwestern China, was retrieved to recover the history of climate changes and lake evolution in the area. Five radiocarbon dates on organic matter were obtained. A chronological sequence is established based on these five dates and other dates from nearby sites. Magnetic susceptibility, particle size and chemical composition were analysized for climate proxies. The proxies indicate that a drier climate prevailed in the Shiyang River drainage during the last glacial. Lake Yiema was dry and eolian sand covered most part of the lake basin. During the early and middle Holocene, a moister climate prevailed in the drainage. Climate became dry stepwise with an abrupt transition from one stage to another during the entire Holocene and became driest since about 4,200 BP. Maximum dry climate spells occurred at about 12,000-10,000 BP and after about 4,200 BP. A dry climate event also existed at about 7,600 BP. Periodical sand storms with about 400-yr cycle happened during the middle Holocene. Desiccation processes of the lake started at 4,200 BP, and were accelerated since the last 2,500 yrs by the inflow water diversion for agriculture irrigation. During the past 2,500 yrs, the lake size has been closed associated with the human population, implying that the human impact has been accelerating the lake desiccation superimposed on the natural climate deterioration.
- Published
- 1999
5. [Correlations between leaf delta13C and physiological parameters of desert plant Reaumuria soongorica]
- Author
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Jian-Ying, Ma, Fa-Hu, Chen, Dun-Sheng, Xia, Hui-Ling, Sun, Zheng-Hu, Duan, and Gang, Wang
- Subjects
Chlorophyll ,Plant Leaves ,Carbon Isotopes ,China ,Proline ,Nitrogen ,Tamaricaceae ,Potassium ,Water ,Desert Climate ,Photosynthesis ,Carbon - Abstract
Reaumuria soongorica is a dominant species in the desert shrubbery vegetation in arid regions of northwestern China, playing an important role in the maintenance of the stability and continuity of desert ecosystem. In this paper, a total of 407 individuals in 21 natural populations of R. soongorica were selected from its main distribution areas to measure the leaf stable carbon isotope composition (delta13C) and nitrogen, phosphorus, potassium, water, proline and chlorophyll contents, with the correlations between the delta13C value and the test physiological parameters analyzed. The results showed that leaf delta13C value was significantly correlated with the contents of leaf potassium, water, and proline (P0.001), and the correlation with leaf potassium content was most profound (r = 0.793), followed by that with leaf water content (r = -0.786), indicating that the variation of leaf delta13C value could reflect the nutritional status of the plants, and also, their water-deficient degree. The different distribution trends in leaf delta13C value of R. soongorica were likely caused by stomatal conductance, rather than by nutrient-related changes in photosynthetic efficiency under extremely low available water conditions.
- Published
- 2008
6. [Magnetic characteristics of street dust in Lanzhou and its environmental significance]
- Author
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Dun-sheng, Xia, Ye, Yu, Jian-ying, Ma, Guan, Wang, Li-ping, Yang, Ming, Jin, Xiu-ming, Liu, and Fa-hu, Chen
- Subjects
Air Pollutants ,China ,Magnetics ,Dust ,Environmental Pollution ,Environmental Monitoring ,Vehicle Emissions - Abstract
Lanzhou has been one of the most seriously polluted cities in the world due to its special geographical location and weather conditions, which make it an ideal place for urban pollution studies. A set of environmental magnetic parameters (chi lf, chi fd%, chi ARM, chi HIRM, SOFT and back field IRM) of the street dust sampled in Lanzhou during spring and summer 2005 were analyzed. These samples were collected along a main street across the urban area and a mountain route from foot to the top. Results demonstrate that the main magnetic minerals in the street dust are magnetite, maghaemite and haematite with some paramagnetic minerals. Plots of Mrs/Ms vs. Bcr/Bc and chi fd% vs. chi ARM/SIRM indicate that the main grain size of magnetic minerals in the street dust are pseudo single domain (PSD). The results reveal that the Lanzhou city is more polluted in spring than in summer. The main pollution sources are anthropogenic activities (81.9%) and natural dust (18.1%), especially the former. The spatial distribution of pollution is controlled by the topography and weather conditions.
- Published
- 2007
7. Early human impacts on vegetation on the northeastern Qinghai-Tibetan Plateau during the middle to late Holocene.
- Author
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Xiao-zhong Huang, Si-si Liu, Guang-hui Dong, Ming-rui Qiang, Zhi-juan Bai, Yan Zhao, and Fa-hu Chen
- Subjects
HOLOCENE Epoch ,NEOLITHIC Period ,NOMADS ,FOREST declines - Abstract
The ecosystems of the Qinghai-Tibetan Plateau are regarded as being primarily regulated by climate because of the harsh environment of the region and the resulting sparse human population. Recent studies have revealed that Neolithic farmers and nomads extensively settled in the northeastern Qinghai-Tibetan Plateau from 5.2 ka (ka = cal ka BP); however, it is unclear how and to what extent human activity has affected its vegetation. Here we combine the results of the pollen analysis of a sediment core from Genggahai Lake, ashallow lake in Gonghe Basin on the northeastern Qinghai-Tibetan Plateau, with archaeological evidence and use them to assess the extent and nature of human impacts on the regional vegetation during the middle and late Holocene. The pollen record indicates that Stellera, an indicator of the extent of grazing-induced grassland degradation, first appeared at 4.7 ka, expanded during 3.6-3.0 ka, and finally increased significantly after 1.6 ka. In support of this finding, archaeological data indicate that the agro-pastoral Majiayao people arrived at ~5 ka and groups of Kayue people, who practiced pastoralism, intensively colonized the Gonghe Basin and nearby Qinghai Lake basin during 3.6-3.0 ka. After~ 1.6 ka, from the Tang Dynasty onwards, human settlement and grazing activity intensified on the northeastern Qinghai-Tibetan Plateau, and this is in accord with the observed high percentages of Stellera in the pollen record. Based on comparison with other records, we conclude that the sediments of Genggahai Lake provide a record of anthropogenic impacts on vegetation, and that human activity may have contributed to regional forest decline during the middle Holocene, and to grassland degradation in the late Holocene. Grassland degradation caused by human activity may be an indicator of the start of the Anthropocene and potentially may have contributed to global climate change via increased dust emission to the atmosphere. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
8. Climate-growth relationships of Qilian juniper Sabina przewalskii in the Anyemaqen Mountains, Tibet.
- Author
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Jian-feng Peng, Xiao-hua Gou, Fa-hu Chen, and Ke-yan Fang
- Subjects
CLIMATOLOGY ,SLOPES (Physical geography) ,JUNIPERS ,LIMITING factors (Ecology) - Abstract
Climate-growth relationships were investigated for 5 mountain slopes of the Anyemaqen Mountains on the northeastern Tibetan Plateau, using a tree-ring width network indicating the chronologies of 20 Qilian junipers Sabina przewalskii. Tree growth is mainly controlled by regional climate conditions, which are modulated by altitudinal factors. The tree growth patterns in this region were classified according to a west-east orientation. Temperature and precipitation from August to October of the previous year and May of the current year are the major limiting factors for most chronologies, as indicated by simple correlation analysis. In general, precipitation plays a more important role in governing tree growth than temperature, and tree rings in the east are more sensitive to precipitation than those in the west. Differences in the climate-growth relationship may be caused by varying climate conditions between the western and eastern Anyemaqen Mountains. [ABSTRACT FROM AUTHOR]
- Published
- 2010
- Full Text
- View/download PDF
9. Agricultural origins and the isotopic identity of domestication in northern China.
- Author
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Barton, Loukas, Newsome, Seth D., Fa-Hu Chen, Hui Wange, Guilderson, Thomas P., and Bettinger, Robert L.
- Subjects
DOMESTIC animals ,AGRICULTURAL policy ,CARBON isotopes ,RADIOCARBON dating - Abstract
Stable isotope biochemistry (δ
13 C and δ15 N) and radiocarbon dating of ancient human and animal bone document 2 distinct phases of plant and animal domestication at the Dadiwan site in northwest China. The first was brief and nonintensive: at various times between 7900 and 7200 calendar years before present (calBP) people harvested and stored enough broomcorn millet (Panicum miliaceum) to provision themselves and their hunting dogs (Canis sp.) throughout the year. The second, much more intensive phase was in place by 5900 calBP: during this time both broomcorn and foxtail (Setaria viridis spp. italica) millets were cultivated and made significant contributions to the diets of people, dogs, and pigs (Sus sp.). The systems represented in both phases developed elsewhere: the earlier, low-intensity domestic relationship emerged with hunter-gatherers in the arid north, while the more intensive, later one evolved further east and arrived at Dadiwan with the Yangshao Neolithic. The stable isotope methodology used here is probably the best means of detecting the symbiotic human-plant-animal linkages that develop during the very earliest phases of domestication and is thus applicable to the areas where these connections first emerged and are critical to explaining how and why agriculture began in East Asia. [ABSTRACT FROM AUTHOR]- Published
- 2009
- Full Text
- View/download PDF
10. A record of Holocene climate change in the Guanzhong Basin, China, based on optical dating of a loess-palaeosol sequence.
- Author
-
Hui Zhao, Fa-Hu Chen, Sheng-Hua Li, Wintle, Ann G., Yu-Xin Fan, and Dun-Sheng Xia
- Subjects
- *
CLIMATE & civilization , *CLIMATE change , *HOLOCENE stratigraphic geology , *ATMOSPHERIC temperature , *SEDIMENTS , *CIVILIZATION , *PALEOPEDOLOGY , *CLIMATOLOGY - Abstract
Optical dating was used to obtain a chronology for a loess-palaeosol sequence in the Guanzhong Basin on the Loess Plateau in China. The sedimentary sequence recorded two dry episodes (3.7~2.4 ka and 1.2~0.8 ka ago) in the Holocene as shown by the presence of two layers of loess within the Holocene deposits. These two arid events are consistent with records of global climate change in the Holocene and also coincident with major historic events in China. This finding suggests that loess-paleosol sequences in China can record global climate changes and implies that rapid climate change affected the progress of human civilization. In addition, changes in the sedimentation rate through the section suggest that agricultural expansion may have accelerated the rate of dust accumulation. [ABSTRACT FROM AUTHOR]
- Published
- 2007
- Full Text
- View/download PDF
11. Hydrological Response of Populus euphratica Olve. Radial Growth in Ejinaa Banner, Inner Mongolia.
- Author
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Pu-Xing Liu, Jian-Feng Peng, and Fa-Hu Chen
- Subjects
TREES ,RUNOFF ,PRINCIPAL components analysis ,GROUNDWATER - Abstract
Populus euphratica Olve. is a dominant tree species in Ejinaa Oasis of the lower reaches of the Heihe River, Inner Mongolia, China. In recent years, the population of this species has shown signs of degradation that are suggested to be probably associated with the decrease of surface water. In this study, the history of river runoff in this region was examined with a dendrochronological study of P. euphratica from four sites. It is found that tree-ring widths in the all sites have negative correlation with runoffs of all months at the Zhengyixia hydrological station. Principal component (PC) analysis of the tree-ring chronologies shows that the first PC (PC1) accounts for 49.98% of the total variances. The first PC is found to have a significantly negative correlation with runoffs in March and April (− 0.52 and − 0.43, respectively, P < 0.05). This negative correlation might be related to variations in the depth of underground water. [ABSTRACT FROM AUTHOR]
- Published
- 2007
- Full Text
- View/download PDF
12. Holocene environmental change inferred from a high-resolution pollen record, Lake Zhuyeze, arid China.
- Author
-
Fa-Hu Chen, Bo Cheng, Yan Zhao, Yan Zhu, and Madsen, David B.
- Subjects
- *
HOLOCENE paleoclimatology , *CLIMATE change , *LAKE sediments , *METEOROLOGICAL precipitation , *PHYSICAL geography , *SEDIMENTATION & deposition , *SEDIMENTARY rocks , *SEDIMENTS , *GEOLOGY - Abstract
A high-resolution pollen record, c. 50 yr/sample, from terminal lake sediments in the Shiyang River drainage basin on the present margin of the summer monsoon was used to reconstruct vegetation and climate history during the Holocene. Forest trees from mountainous areas of the drainage, including Sabina, Picea and Pinus, dominated pollen assemblages in the early Holocene (11.6–7.1 cal. ka). In the mid-Holocene (7.1–3.8 cal. ka) desert and steppe shrubs and herbs around the lake, including Nitraria, Poaceae, Compositae and Artemisia, were dominant. The late Holocene (3.8–0 cal. ka) was again dominated by alternation of Pinus–Sabina tree pollen and desert-steppe pollen. The early Holocene forest expansion in the mountains and subsequent increase in the river transport of tree pollen corresponds with maximum precipitation during the East Asian summer monsoon maximum. The timing of these changes in our record from arid China is different from that of East China, where the Holocene monsoon maximum appeared in the middle Holocene. This difference indicates that the extent and development of summer monsoon circulation in the Holocene was complex. Changes in the pollen record appear to show pervasive and persistent centennial- to millennial-scale oscillations throughout both wet and dry periods of the Holocene. Our results imply the continental interior was sensitive to changing moisture conditions and responsive to Holocene climatic events. [ABSTRACT FROM AUTHOR]
- Published
- 2006
- Full Text
- View/download PDF
13. Atmospheric particulate pollution of Lanzhou using magnetic measurements.
- Author
-
Fa-hu, Chen and Li-ping, Yang
- Subjects
- *
AIR pollution - Abstract
Differentiates natural and anthropogenic particulate sources in the atmosphere in Lanzhou City, China by collecting samples in different sites. Sampling and laboratory methods; Variations of seasonal atmospheric particulate flux; Variation of the magnetic susceptibility of the atmospheric particulate; Conclusion.
- Published
- 1999
14. Environmental changes documented by sedimentation of Lake Yiema in arid China since the late Glaciation.
- Author
-
Fa-Hu Chen, Qi Shi, and Jian-Min Wang
- Subjects
SEDIMENTATION & deposition ,LAKE sediments ,CLIMATE change ,LAKES - Abstract
In this study, a 6 m long core (16,000 BP) at the center of the dry Lake Yiema, a closed lake of Shiyang River drainage in Minqin Basin of the arid northwestern China, was retrieved to recover the history of climate changes and lake evolution in the area. Five radiocarbon dates on organic matter were obtained. A chronological sequence is established based on these five dates and other dates from nearby sites. Magnetic susceptibility, particle size and chemical composition were analysized for climate proxies. The proxies indicate that a drier climate prevailed in the Shiyang River drainage during the last glacial. Lake Yiema was dry and eolian sand covered most part of the lake basin. During the early and middle Holocene, a moister climate prevailed in the drainage. Climate became dry stepwise with an abrupt transition from one stage to another during the entire Holocene and became driest since about 4,200 BP. Maximum dry climate spells occurred at about 12,000-10,000 BP and after about 4,200 BP. A dry climate event also existed at about 7,600 BP. Periodical sand storms with about 400-yr cycle happened during the middle Holocene. Desiccation processes of the lake started at 4,200 BP, and were accelerated since the last 2,500 yrs by the inflow water diversion for agriculture irrigation. During the past 2,500 yrs, the lake size has been closed associated with the human population, implying that the human impact has been accelerating the lake desiccation superimposed on the natural climate deterioration. [ABSTRACT FROM AUTHOR]
- Published
- 1999
- Full Text
- View/download PDF
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