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Understanding the seasonal behaviour of a subtropical forest and its inter-annual variation is crucial to understanding and monitoring its ecosystem function in the context of global warming. Based on the Moderate Resolution Imaging Spectroradiometer (MODIS) Enhanced Vegetation Index dataset, a wavelet transform method was used to investigate the inter-annual variations of vegetation phenology in a subtropical mountain and hill region in Fujian, China, during 2001-2010. The results show a distinct inter-annual variation of vegetation phenology related to climate variability even if most areas presented non-significant trends. The start dates significantly advanced and end dates delayed in 2003 and 2008, due to anomalously warm conditions. There was generally a gradient of increasing start dates, and earlier end dates of vegetation growing season, due to colder temperatures at higher altitudes. However, the altitudinal phenology relationship also depends on its corresponding rainfall conditions. Earlier start dates were observed at higher altitudes during rainfall deficit years such as 2008, which coincides with relatively abundant rainfall at higher altitudes. This paper reveals that vegetation phenology was coupled with altitudinal gradient, with distinct responses at different combinations of alternate temperature and precipitation conditions variability. [ABSTRACT FROM AUTHOR]

Using the definition of vulnerability provided by the Intergovernmental Panel on Climate Change, this paper assesses the vulnerability of areas affected by Chinese cryospheric changes from 2001 to 2020 and from 2001 to 2050 in A1 and B1scenarios. Seven indices are used in the vulnerability assessment: glacial area fraction, interannual variability of permafrost depth, interannual variability of surface snow area fraction, interannual variability of surface runoff, interannual variability of surface temperature, interannual variability of vegetation growth, and interannual variability of the human development index. Assessment results show that the overall vulnerability of the studied areas in China increases from east to west. The areas in the middle and eastern parts of China are less vulnerable compared with western parts and parts of the Tibetan Plateau. The highest vulnerability values are found from 1981 to 2000, and the least ones are found from 2001 to 2050. The vulnerable areas increase from the period of 1981 to 2000 to the period of 2001 to 2050, and the less vulnerable areas decrease. The highly vulnerable areas increase from the period of 1981 to 2000 to the period of 2001 to 2020 and then decrease from the period of 2001 to 2020 to the period of 2001 to 2050. This decrease in vulnerability is attributed to the decrease in exposure and sensitivity to Chinese cryospheric changes along with a concomitant increase in adaptation. [ABSTRACT FROM AUTHOR]

This paper presents a multi-proxy reconstruction of the climate change in Caotanhu wetland using pollen, phytolith and charcoal records, and the data of loss of ignition (LOl), grain size analysis, and susceptibility. Results reveal that between 4550 and 2500 cal. a BP, a dry climatic condition was not favorable for the accumulation of peat. Since 2500 cal. a BP, the climate became humid and the wetland developed with abundant freshwater aquatic plants, which contributed to peat accumulation. Nevertheless, alternate periods of rain and dry climate occurred during that period. Between 2500 and 1810 cal. a BP (550 BC-140 AD), the climate was more humid than at present. A lot of emerged plants, such as Phragmites, Typha and Sparganium, and freshwater green algae grew in the wetland which was surrounded by desert-steppe vegetation composed mainly of Chenopodiaceae, Artemisia, Compositae and Thalictrum. However, from 1810 to 1160 cal. a BP (140-790 AD), the water level started to decrease and hydrophyte species reduced greatly, but some Phragmites still grew in the wetland and around it was desert vegetation with high proportion of Chenopodiaceae and Artemisia. Then from 1160 to 650 a BP (790-1300 AD), it entered a period of desert-steppe with abundant mesic and xerophytic plants. And a lot of aquatic plants prevailed in the wetland. Here, what is noticeable is that percentages of arboreal pollen, consisting mainly of Betula and Picea, increased greatly and reached a maximal value of 27.2%, in which, Betula percentages rose to 23.2%. Hence, it is reasonable to conclude that Betula grew in the highland of the wetland, or Picea timberline shifted downward resulting in the increase of percentages of Betula and Picea pollen, which were transported into the wetland by flood or wind. But since 650 cal. a BP, desert vegetation prevailed around the wetland again with dominant Chenopodiaceae and Artemisia, and the climate was similar to modern one. Despite some aquatic plants still growing in the wetland at that time, their amounts diminished greatly. [ABSTRACT FROM AUTHOR]

Recent climatic changes have affected terrestrial net primary productivity (NPP). This paper presents an investigation of the impact of climatic changes on Chinese terrestrial vegetation NPP by analyzing 18 years' (1982 to 1999) climatic data and satellite observations of vegetation activity. Results indicate that climatic changes in China have eased some critical climatic constraint on plant growth. (1) From 1982 to 1999, modeled NPP increased by 1.42% · a-1 in water-limited regions of Northwest China, 1.46% · a-1 in temperature-limited regions of Northeast China and Tibet Plateau, and 0.99% · a-1 in radiation-limited regions of South China and East China. (2) NPP increased by 24.2%, i.e. 0.76 petagram of carbon (Pg C) over 18 years in China. Changes in climate (with constant vegetation) directly contributed nearly 11.5% (0.36 Pg C). Changes in vegetation (with constant climate) contributed 12.4% (0.40 Pg C), possibly as a result of climate-vegetation feedbacks, changes in land use, and growth stimulation from other mechanisms. (3) Globally, NPP declined during all three major El Niño events (1982 to 1983, 1987 to 1988, and 1997 to 1998) between 1982 and 2000, but Chinese vegetation productivity responded differently to them because of the monsoon dynamics. In the first three events (1982 to 1983, 1987 to 1988, and 1992), Chinese vegetation NPP declined, while in the later two events (1993, 1997 to 1998) increasing obviously. [ABSTRACT FROM AUTHOR]

This paper applies climate change scenarios in China based on the SRES assumptions with the help of RCMs projections by PRECIS (providing regional climates for impacts studies) system introduced to China from the Hadley Centre for Climate Prediction and Research at a high-resolution (50 km×50 km) over China. This research focuses on B2 scenario of SRES. A biogeochemical model "Atmosphere Vegetation Integrated Model (AVIM2)" was applied to simulating ecosystem status in the 21st century. Then vulnerability of ecosystems was assessed based on a set of index of mainly net primary production (NPP) of vegetation. Results show that climate change would affect ecosystem of China severely and there would be a worse trend with the lapse of time. The regions where having vulnerable ecological background would have heavier impacts while some regions with better ecological background would also receive serious impacts. Extreme climate even would bring about worse impact on the ecosystems. Open shrub and desert steppe would be the two most affected types. When the extreme events happen, vulnerable ecosystem would extend to part of defoliate broad-leaved forest, woody grassland and evergreen conifer forest. Climate change would not always be negative. It could be of some benefit to cold region during the near-term. However, in view of mid-term to long-term negative impact on ecosystem vulnerability would be enormously. [ABSTRACT FROM AUTHOR]

Fossil pollen records from 45 sites across China were evaluated and synthesized to document vegetation and climate change during Marine Isotope Stage 3 (MIS 3) at 60-27 ka and to understand the large-scale controls. During MIS3, vegetation type was dominantly forest in eastern China, forest steppe/meadow in the north and Tibetan Plateau, and steppe desert in northwestern arid China. We developed a semi-quantitative vegetation index to reflect change in plant abundance (by inferring the general climate conditions), with a vegetation score from 1 to 3 based on the different vegetation types inferred from pollen data at individual sites at intervals of 2,000 years. The reconstructed vegetation index shows higher values during MIS 3, especially during the period 53-40 ka, than at the Last Glacial Maximum. Our results also suggest that climate on the basis of vegetation change was cooler and drier during MIS 3 than during the Holocene optimum; however, MIS 3 vegetation was probably similar to modern vegetation. The close relationship between vegetation change, insolation and Asian summer monsoon strength suggests that climate variations, probably in both temperature and precipitation, are the primary drivers of regional vegetation change. Additional well-dated, high-resolution palaeoclimate records from many locations across China will be needed to understand the vegetation change and climate forcings on millennial and centennial scales within MIS 3. [ABSTRACT FROM AUTHOR]

In order to study vegetation evolution and environmental change during 3.15-0.67 Ma, a total of 608 pollen samples with an average time resolution of 4 ka has been analyzed from ODP Site 1145 (water depth 3175 m), northern South China Sea. The deep-sea sediments (213.62-91.9 m) cover from 3.15 to 0.67 Ma based on micropaleonotological stratigraphy. The characteristic features of the pollen diagram include that, pollen influx rises twice obviously around 2.58 Ma and during 2.0-1.8 Ma, in response to global climatic cooling and winter monsoon enhancement. Before 2.58 Ma, tropical and subtropical vegetation, mainly evergreen Quercus (E) and Altingia, predominated around northern SCS with much more tropical montane conifers and ferns relatively. From 2.58 Ma, temperate vegetation increased obviously, implying climatic cooling and winter monsoon enhancement. Spectral analysis shows that percentage variation in tropical and subtropical taxa has a strong 20 ka procession cycle probably due to the summer monsoon; while pollen influx has 100, 41 and 19 ka cycles, indicating the sea level and winter monsoon change response to the ice-sheet variations. [ABSTRACT FROM AUTHOR]

Based on modern pollen studies and reliable chronology of nine AMS 14C dates, a detailed history of vegetation and climate changes during the past 8660 cal. a BP was reconstructed by a high-resolution pollen record from Ugii Nuur in central Mongolia. Poaceae-steppe dominated the study area and the climate was mild and semi-humid before 7800 cal. a BP with a noticeable cool and humid interval at 8350-8250 cal. a BP. Xerophytic plant increased and the climate became warm and dry gradually since 7800 cal. a BP. From 6860 to 3170 cal. a BP, semi-desert steppe expanded, suggesting a prolonged warm and dry climate. Between 3170 and 2340 cal. a BP, regional forest steppe expanded whereas semi-desert steppe retreated, indicating the climate became cool and wet gradually and the humidity reached the maximum at the end of this stage. From 2340 to 1600 cal. a BP, a general cool and wet climate prevailed. And the climatic instability increased after 1600 cal. a BR Review of regional published palaeoclimatic records implies that the mid-Holocene dry climate might have prevailed in vast areas from central Mongolia to arid areas of northwest China. Pollen-based climate reconstruction for UGO4 core was well correlated with the result of climate model on Central Asia by Bush. In addition, several abrupt climatic events (cool and wet) were found and some could be broadly compared with the cool events in Atlantic. [ABSTRACT FROM AUTHOR]

Empirical Orthogonal Function (EOF) analysis and the related Principal Components (PC) analysis are used to extract valuable vegetation cover derived information from the National Oceanic and Atmospheric Administration (NOAA-AVHRR)'s Leaf Area Index (LAI) satellite images. Results suggest that from 1982 to 2000 global climate change has contributed to an increase in vegetation cover in the Qinghai-Tibet Plateau. The correlation between rainfall and LAI EOF PC1 and PC2 indicates that rainfall is the major climatic factor influencing interannual variations of average vegetation cover throughout the entire Plateau. However, annual mean vegetation cover trends in the Qinghai-Tibet Plateau are mainly out of phase with air temperature increasing, which is primarily responsible for nonsynchronous changes of vegetation cover. In the southern ridge of the Qinghai-Tibet Plateau, recent warming trends contribute to humid weather and favorable conditions for vegetation growth. By contrast, higher temperatures have led to arid conditions and insufficient rainfall in the northern part of the Plateau, leading to drought and other climatic conditions which are not conducive to increased vegetation cover. [ABSTRACT FROM AUTHOR]