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1.
Responses of primary productivity to current and climate changes in the mud area to the southwest of Cheju Island during the past 800 years 总被引：1，自引：1，他引：0
Yi Liu Xin Zhou Wen Huang Yuhong Wang Nan Jia Haoyuan Ji Yiya Huang Liguang Sun 《中国海洋大学学报(英文版)》2013,12(4):605-610
The biogenic silica (BSi), total organic carbon (TOC), total nitrogen (TN) and grain size were analyzed with a gravity core (3250-6) collected from the mud area in the north East China Sea. The average deposition rate of the upper core was about 0.078 cm yr?1 based on the results of 210Pbex. The mean grain size increased with depth in general. The frequency distribution of grain size showed that two marked changes of deposition environment occurred at 30 cm and 50 cm depths (about 1550 AD and 1300 AD, respectively). The variations of BSi and TOC indicated two distinct major periods of primary productivity over the past 800 years: a stage of low primary productivity corresponding to weak upwelling and low nutrient input below 30 cm depth (about 1200–1550 AD), and a stage of high primary productivity with strong currents and upwelling above 30 cm depth (about 1550–1950 AD). The stage with high primary productive appeared to be due to the northward-expanded muddy area caused by strong Asian Winter Monsoon and enhanced Yellow Sea Warm Current in winter. In conclusion, the BSi and TOC in the muddy sediments, the symbols of marine primary productivity, can be then used to investigate the evolution history of currents and relative climate change in the offshore areas. 相似文献
2.
To predict future spatio-temporal patterns of climate change, we should fully understand the spatio-temporal patterns of climate change during the past millennium. But, we are not yet able to delineate the patterns because the qualities of the retrieved proxy records and the spatial coverage of those records are not adequate. Northern Xinjiang of China is one of such areas where the records are not adequate. Here, we present a 500-yr land-surface moisture sequence from Heiyangpo Peat (48.34°N, 87.18°E, 1353 m a.s.l) in the southern Altai Mountains within northern Xinjiang. Specifically, peat carbon isotope value of cellulose (δ13Ccellulose) was used to estimate the warm-season moisture variations and the degree of humification was used to constrain the δ13Ccellulose-based hydrological interpretation. The climatic attributions of the interpreted hydrological variations were based on the warm-season temperature reconstructed from Belukha ice core and the warm-season precipitation inferred from the reconstructed Atlantic Multidecadal Oscillations (AMO). The results show that humification decreased and the δ13Ccellulose-suggested moisture decreased from ~1510 to ~1775 AD, implying that a constant drying condition may have inhibited peat decay. Our comparison with reconstructed climatic parameters suggests that the moisture-level decline was most likely resulted from a constant decline of precipitation. The results also show that humification kept a stable level and the δ13Ccellulose-suggested moisture also decreased from ~1775 to ~2013 AD, implying that peat decay in the acrotelm primarily did not depend on the water availability or an aerobic environment. Again, our comparison with reconstructed climatic parameters suggests that the land-surface moisturelevel decline was most likely resulted from a steady warming of growing-season temperature. 相似文献
3.
Ecosystem response to climate change in high-altitude regions is a focus on global change research. Picea/Abies forests are widely distributed at high altitudes of East and Central Asia, and their distribution changes are sensitive to climate change. Humidity is an important climatic factor that affects high-altitude ecosystems; however, the relationship between distribution changes of Picea/Abies forests and millennial-scale variability of humidity is still not dear. Palynological records can provide insights into millennial-scale paleovegetation changes, which have been successfully used to reconstruct past climate change in East and Central Asia. In this study, we synthesized 24 Picea/Abies pollen and humidity/moisture changes based upon Holocene lake records in East and Central Asia in order to explore the response of high-latitude ecosystem to millennial-scale climate change. The changing pattern of Holocene lacustrine Picea/Abies pollen in arid Central Asia differs from that of monsoonal East Asia, which can be due to different millennial-scale climate change patterns between monsoonal and arid Central Asia. Then, the relationship between changes in Picea/Abies pollen and humidity/moisture conditions was examined based on a comparison of pollen and humidity/moisture records. The results indicate that millennial-scale Picea/Abies distribution changes aremainly controlled by moisture variability at high altitudes, while the temperature effect plays a minor role in Picea/Abies distribution changes. Moreover, this research proves that lacustrine Picea/Abies pollen can be used as an indicator of millennial-scale humidity/moisture evolution at high altitudes in East and Central Asia. 相似文献
4.
The role of forests is being actively considered under the agenda of REDD+ (Reducing Emissions from Deforestation and Forest Degradation plus) aimed at reducing emissions related to changes in forest cover and forest quality. Forests in general have undergone negative changes in the past in the form of deforestation and degradation, while in some countries positive changes are reported in the form of conservation, sustainable management of forests and enhancement of carbon stock. The present study in the Kashmir Himalayan forests is an effort to assess historical forest cover changes that took place from 1980 to 2009 and to predict the same for 2030 on the basis of past trend using geospatial modeling approach. Landsat data (Multispectral Scanner (MSS), Thematic Mapper (TM) and Enhanced Thematic Mapper (ETM+)) was used for the years 1980, 1990 and (2001, 2009) respectively and change detection analysis between the dates was performed. The maps generated were validated through ground truthing. The study area (3375.62 km2) from 1980-2009 has uffered deforestation and forest degradation of about 126 km2 and 139.02 km2 respectively which can be claimed under negative options of REDD+, while as the area that experienced no change (1514 km2) can be claimed under conservation. A small area (23.31 km2) observed as positive change can be claimed under positive options. The projected estimates of forest cover for 2030 showed increased deforestation and forest degradation on the basis of trend analysis using Cellular Automata (CA) Markov modeling. Despite the fact that country as a whole has registered a net positive change in the past few decades, but there are regions like Kashmir region of western Himalaya which have constantly undergoing deforestation as well as degradation in the past few decades. 相似文献
5.
Based on the new data of the Quaternary along the coast of Hainan Island, China, this paper puts forward that the Holocene in Hainan Island can be divided into four formations: Wanning formation (Q41), Sanya formation (Q42-1), Qiongshan formation (Q42-2) and Ledong formation (Q43). Spore-pollen analysis shows that there are 6 spore-pollen zones existed, reflecting two cycles of climatic fluctuation from warm-dry to hot-humid. The climax of hot-humid period occurred 6,000-5,000 years B.P.. Based on the 14C dating data of the 38 samples representing the positions of ancient sea level, a breakthrough curve representing the sea level change during the Holocone is obtained, in which , a sea level change caused by tectonic movement is subtracted. Two cycles of rise-drop of sea level with three periods of high sea level were found. The period with the highest sea level is some 6,000-5,000 years B.P.. According to the rise-drop rate of sea level, four periods of the sea level change can be distinguished in the 相似文献
6.
Based on plant specimen data, sediment samples, photos, and sketches from 45 coastal crosssections, and materials from two
recent countrywide comprehensive investigations on Chinese coasts and islands, this paper deals with China’s vegetative tidal-flats:
salt marshes and mangrove swamps. There are now 141700 acres of salt marshes and 51000 acres of mangrove swamps which together
cover about 30% of the mud-coast area of the country and distribute between 18°N (Southern Hainan Island) and 41 °N (Liaodong
Bay). Over the past 45 years, about 1750000 acres of salt marshes and 49400 acres of mangrove swamps have been reclaimed.
The 2.0×109 tons of fine sediments input by rivers into the Chinese seas form extensive tidal flats, the soil basis of coastal helophytes.
Different climates result in the diversity of vegetation. The 3∼8 m tidal range favors intertidal zone development. Of over
20 plant species in the salt marshes, nativeSuaeda salsa, Phragmites australis, Aeluropus littoralis, Zoysia maerostachys, Imperata cylindrica and introducedSpartina anglica are the most extensive in distribution. Of the 41 mangrove swamps species,Kandelia candel, Bruguiera gymnorrhiza, Excoecaria agallocha andAvicennia marina are much wider in latitudinal distribution than the others. Developing stages of marshes originally relevant to the evolution
of tidal flats are given out. The roles of pioneer plants in decreasing flood water energy and increasing accretion rate in
the Changjiang River delta are discussed.
The project was supported by the NSFC (No. 49476281). 相似文献
7.
EFFECTS OF AGRICULTURE RECLAMATION ON THE HYDROLOGIC CHARACTERISTICS IN THE SANJIANG PLAIN, CHINA 总被引：1，自引：1，他引：0
1 THE NATURAL ENVIRONMENTAL CHARACTERISTICS The Sanjiang Plain is located in the northeast of Heilongjiang Province, China. Russia borders this region in the north and east. Its total area is 1.088×107ha. The area of plain occupies 61.21％of the total land area and that of hill and mountain amounts to 38.79％of the total land area. It is not only one of the most important regions with large area of fresh water wetlands and with varieties of rare migratory waterfowls, but a… 相似文献
8.
Little has been done in measurement and research of the flux of CH4 emission from paddy fields in Changchun area, Jilin Province, China before 1994. So the purpose of the study is to offer
available regional data of CH4 emission flux and to discuss the factors which affect CH4 emission from paddy fields. Experimental paddy fields are chosen using TM pictures respectively in Xinlicheng (43°49′N, 125°20′E)
of the Yitong River’s and in Wanchang (43°44′10″N, 125°53′11″E) of the Yinma River’s alluvial plain. The fluxes of CH4 emission from paddy fields are measured by the method of static chamber in Changchun area in 3 consecutive years. The research
results show that the peak of CH4 emission from paddy fields occurs during the booting stage. The mean fluxes of CH4 emission are 7.056 mg/m(2 · h) and 0.489 mg/(m2 · h) in the paddy fields of flood and discontinuous irrigation respectively. The contrastive study holds that climate condition,
the way of water management and fertilizer variation have significant influence on fluxes of CH4 emission from paddy fields. The difference of climatic conditions causes the interannual change of the flux of CH4 emission from paddy fields. In general, the flux of CH4 emission from paddy fields of flood irrigation is greater than that from paddy fields of discontinuous irrigation. To change
the way of water management perhaps in an available way to reduce CH4 emission flux from paddy fields.
Foundation item: Under the auspices of Jilin Commttee of Science and Technology (grant 963416 - 1), and Changchun Jingyuetan
Remote Sensing Test Site of the Chinese Academy of Sciences (grant 9504).
Biography: YAN Min-hua (1964 -), female, a native of Liaoning Province, master, associate professor. Her research interests
include climate change, greenhouse gases and wetland climate. 相似文献
9.
近几十年来, 由气候变化和人类活动共同驱动的内蒙古地区土地利用/覆被变化(LUCC)较为剧烈, 其引发了一系列的生态环境问题。本文基于3 期LUCC数据, 借助于变化率指数、动态度指数、转类矩阵, 在全区和地级市尺度上, 分析了内蒙古地区土地利用/覆被变化的时空特征及驱动因素。研究结果显示, 受地形因素的影响, 研究区土地利用/覆被变化表现出明显的区域差异及区域趋同性。在经济发展和人口增长的双重压力下:(1)平原耕作区深受国家宏观政策的影响, 2000 年之后的“林地、高覆盖草地开垦”总体速度下降了近35%;(2) 平原耕作区北部边缘条带状地区、山区草原区受制于降水不显著的波动呈减少态势, 2000 年之后的“草地退化及荒漠化”趋势加强了近85%。研究结果为内蒙古地区土地资源的可持续利用与科学管理提供了依据。 相似文献
10.
Wind and waves are key components of the climate system as they drive air-sea interactions and influence weather systems and atmospheric circulation. In marine environments, understanding surface wind and wave fields and their evolution over time is important for conducting safe and efficient human activities, such as navigation and engineering. This study considers long-term trends in the sea surface wind speed(WS) and significant wave height(SWH) in the China Seas over the period 1988–2011 using the Cross-Calibrated Multi-Platform(CCMP) ocean surface wind product and a 24-year hindcast wave dataset obtained from the WAVEWATCH-III(WW3) wave model forced with CCMP winds. The long-term trends in WS and SWH in the China Seas are analyzed over the past 24 years to provide a reference point from which to assess future climate change and offshore wind and wave energy resource development in the region. Results demonstrate that over the period 1988–2011 in the China Seas: 1) WS and SWH showed a significant increasing trend of 3.38 cm s~(-1)yr~(-1) and 1.52 cm yr~(-1), respectively; 2) there were notable regional differences in the long-term trends of WS and SWH; 3) areas with strong increasing trends were located mainly in the middle of the Tsushima Strait, the northern and southern areas of the Taiwan Strait, and in nearshore regions of the northern South China Sea; and 4) the long-term trend in WS was closely associated with El Ni?o and a significant increase in the occurrence of gale force winds in the region. 相似文献
11.
ＲＥＬＡＴＩＯＮＳＨＩＰＢＥＴＷＥＥＮＱＩＮＧＨＡＩＬＡＫＥＬＥＶＥＬＤＥＳＣＥＮＤＩＮＧＡＮＤＡＲＴＩＦＩＣＩＡＬＷＡＴＥＲ－ＣＯＮＳＵＭＰＴＩＯＮ￥ＰｅｎｇＭｉｎ（彭敏）ＣｈｅｎＧｕｉｃｈｅｎ（陈桂琛）ＺｈｏｕＬｉｈｕａ（周立华）（Ｎｏｒｔｈｗｅ... 相似文献
12.
Tropical glaciers are extremely sensitive to a warming climate. In this paper, the evolution of the remaining tropical glaciers in Australasia(Irian Jaya, Indonesia) during the period 1988-2015 was quantified. Landsat series images, a digital elevation model from SRTM, and previously published data were used. Estimated total glacier area in 1988, 1993, 1997 and 2004 was 3.85 km2±0.13 km2, 3.01 km2±0.08 km2, 2.49 km2±0.07 km2 and 1.725 km2 ±0.042 km2, respectively. Only 0.58 km2±0.016 km2 glacierized area remained in 2015 in Puncak Jaya, which is about 84.9% loss in just 27 years. If this rate continued, the remaining tropical glaciers in Australasia would disappear in the 2020 s. Timeseries analysis of climate variables showed significant positive trends in air temperature(0.009°C per year) and relative humidity(0.43% per year) but no considerable tendency was observed for precipitation. Warming climate together with mining activities would accelerate loss of glacier coverage in this region. 相似文献
13.
14.
The palynolpgical study on the Quaternary sediments of 42 cores in the region of the Yangtze River Delta and the sections of 4 relics had been done since 1960. Palynological assemblages from the region of the Yangtze River Delta, showing obviously .common characteristics but with slight differences because of the vast areas covered, can be divided into five spores and pollen zones and three subzones in ascendant order:I.Quercus alienc-Pinus-Cupressaceae-Chenopodiaceae spores and pollen zone reflecting the cool, then cold and dry climate--Preboreal.II.Quercus dentata-Quefcus acutissima-Pinus-Castanea-Artemisia spores and pollen zone reflecting the temperate and cool, but a little dry climate--Boreal.III.Quercus glauca-Caslanopsis-Myrica-Caslanea spores and pollen zone reflecting the hot and moist climate--Atlantic.IV.Quercus acutissima-Pinus-Castanea-Quercus glauca- Chenopodiaceae spores and pollen zone reflecting the warm, and a little dry climate--Subboreal.V.Quercus acutissima-Costarica-Quercus glauca 相似文献
15.
16.
José Antonio López-Sáez Francisca Alba-Sánchez Sandra Robles-López Sebastián Pérez-Díaz Daniel Abel-Schaad Silvia Sabariego-Ruiz Arthur Glais 《山地科学学报》2016,13(7):1139-1153
A high-altitude peat sequence from the heart of the Spanish Central System (Gredos range) was analysed through a multi-proxy approach to determine the sensitivity of high-mountain habitats to climate, fire and land use changes during the last seven hundred years, providing valuable insight into our understanding of the vegetation history and environmental changes in a mountain pass close to a traditional route of transhumance. The pollen data indicate that the vegetation was dominated by shrublands and grasslands with scattered pines in high-mountain areas, while in the valleys cereals, chestnut and olive trees were cultivated. Strong declines of high-mountain pines percentages are recorded at 1540, 1675, 1765, 1835 and 1925 cal AD, which may be related to increasing grazing activities and/or the occurrence of anthropogenic fires. The practice of mountain summer farming and transhumance deeply changed and redesigned the landscape of the high altitudes in central Spain (Gredos range) since the Middle Ages, although its dynamics was influenced in some way by climate variability of the past seven centuries. 相似文献
17.
Land use changes in Northeast China driven by human activities and climatic variation 总被引：5，自引：0，他引：5
Zongming Wang Zhiming Liu Kaishan Song Bai Zhang Sumei Zhang Dianwei Liu Chunying Ren Fei Yang 《中国地理科学(英文版)》2009,19(3):225-230
Human-induced land use/cover change (LUCC) forms an important component of global environmental change. Therefore, it is important
to study land use/cover and its change at local, regional and global scales. In this paper we conducted the study of land
use change in Northeast China, one of the most important agricultural zones of the nation. From 1986 to 2000, according to
the study results obtained from Landsat images, widespread changes in land use/cover took place in the study area. Grassland,
marsh, water body and woodland decreased by 9864, 3973, 1367 and 10,052km2, respectively. By comparison, paddy field, dry farmland, and built-up land expanded by 7339, 17193 and 700km2, respectively. Those changes bore an interactive relationship with the environment, especially climate change. On the one
hand, climate warming created a potential environment for grassland and marsh to be changed to farmland as more crops could
thrive in the warmer climate, and for dry farmland to paddy field. On the other hand, the changed surface cover modified the
local climate. Those changes, in turn, have adversely influenced the local environment by accelerating land degradation. In
terms of socio-economic driving forces, population augment, regional economic development, and national and provincial policies
were confirmed as main driving factors for land use change.
Foundation item: Under the auspices of the Knowledge Innovation Programs of Chinese Academy of Sciences (No. KZCX2-YW-341),
National Natural Science Foundation of China (No. 40871187, 40801208) 相似文献
18.
Lei Xing Yiqing Jiang Zineng Yuan Hailong Zhang Li Li Liping Zhou Meixun Zhao 《中国海洋大学学报(英文版)》2013,12(4):599-604
As an important marginal sea under the influences of both the Changjiang River and the Kuroshio, the East China Sea (ECS) environment is sensitive to both continental and oceanic forcing. Paleoenvironmental records are essential for understanding the long-term environmental evolution of the ECS and adjacent areas. However, paleo-temperature records from the ECS shelf are currently very limited. In this study, the U 37 K′ and TEX86 paleothermometers were used to reconstruct surface and subsurface temperature changes of the mud area southwest of the Cheju Island (Site F10B) in the ECS during the Holocene. The results indicate that temperature changes of F10B during the early Holocene (11.6–6.2 kyr) are associated with global climate change. During the period of 6.2–2.5 kyr, the similar variability trends of smoothing average of ΔT (the difference between surface and subsurface temperature) of Site F10B and the strength of the Kuroshio suggest that the Kuroshio influence on the site started around 6.2 kyr when the Kuroshio entered the Yellow Sea and continued to 2.5 kyr. During the late Holocene (2.5–1.45 kyr), apparent decreases of U 37 K′ sea surface temperature (SST) and ΔT imply that the direct influence of the Kuroshio was reduced while cold eddy induced by the Kuroshio gradually controlled hydrological conditions of this region around 2.5 kyr. 相似文献
19.
Maritime-type glaciers in the eastern Nyainqêntanglha Range, located in the southeastern part of the Tibetan Plateau, are an important water source for downstream residents and ecological systems. To better understand the variability of glaciers in this region, we used the band ratio threshold(TM3/TM5 for the Landsat TM /ETM+ and TM4/TM6 for Landsat OLI) to extract glacier outlines in ~1999 and ~2013. After that, we also generated a series of glacier boundaries and monitored glacier variations in the past 40 years with the help of the Chinese Glacier Inventory data(1975) and Landsat TM, ETM+ and OLI data. The total glacier area decreased by 37.69 ± 2.84% from 1975 to 2013. The annual percentage area change(APAC) was ~1.32% a-1 and ~1.29% a-1 in the periods 1975-1999 and 1999-2013, respectively. According to the lag theory, the reaction time is probably about 10 years and we discuss the variations of temperature and precipitation between 1965 and 2011. Temperature and precipitation increased between 1965 and 2011 at a rate of 0.34°C /10 a and 15.4 mm/10 a, respectively. Extensive meteorological data show that the glacier shrinkage rate over the period may be mainly due to increasing air temperature, while the increasing precipitation partly made up for the mass loss of glacier ice resulting from increasing temperature may also lead to the low APAC between 1999 and 2013. The lag theory suggests that glacier shrinkage may accelerate in the next 10 years. Small glaciers were more sensitive to climate change, and there was a normal distribution between glacier area and elevation. Glaciers shrank in all aspects, and south aspects diminished faster than others. 相似文献
20.
1 INTRODUCTION δ13C in organic matters from lacustrine sedi- ments varies with several factors including aquatic plants, vegetation type in the catchment, atmos- pheric CO2 concentration, climate (temperature and precipitation), and properties of water, … 相似文献