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Variations in vegetation are closely related to climate change, but understanding of their characteristics and causes remains limited. As a typical semi-humid and semi-arid cold plateau region, it is important to understand the knowledge of long term Normalized Difference Vegetation Index (NDVI) variations and find the potential causes in the source region of the Yangtze River. Based on four tree-ring width chronologies, the regional mean NDVI for July and August spanning the period 1665–2013 was reconstructed using a regression model, and it explained 43.9% of the total variance during the period 1981–2013. In decadal, the reconstructed NDVI showed eight growth stages (1754–1764, 1766–1783, 1794–1811, 1828–1838, 1843–1855, 1862–1873, 1897–1909, and 1932–1945) and four degradation stages (1679–1698, 1726–1753, 1910–1923, and 1988–2000). And based on wavelet analysis, significant cycles of 2–3 yr and 3–8 yr were identified. In additional, there was a significant positive correlation between the NDVI and the Palmer Drought Severity Index (PDSI) during the past 349 yr, and they were mainly in phase. However, according to the results of correlation analysis between different grades of drought/wet and NDVI, there was significant asymmetry in extreme drought years and extreme wet years. In extreme drought years, NDVI was positively correlated with PDSI, and in extreme wet years they were negatively correlated.

The large variety of atmospheric circulation systems affecting the eastern Asian climate is reflected by the complex Asian vegetation distribution. Particularly in the transition zones of these circulation systems, vegetation is supposed to be very sensitive to climate change. Since proxy records are scarce, hitherto a mechanistic understanding of the past spatio-temporal climate-vegetation relationship is lacking. To assess the Holocene vegetation change and to obtain an ensemble of potential mid-Holocene biome distributions for eastern Asia, we forced the diagnostic biome model BIOME4 with climate anomalies of different transient Holocene climate simulations performed in coupled atmosphere-ocean(-vegetation) models. The simulated biome changes are compared with pollen-based biome records for different key regions. In all simulations, substantial biome shifts during the last 6000 years are confined to the high northern latitudes and the monsoon-westerly wind transition zone, but the temporal evolution and amplitude of change strongly depend on the climate forcing. Large parts of the southern tundra are replaced by taiga during the mid-Holocene due to a warmer growing season and the boreal treeline in northern Asia is shifted northward by approx. 4 degrees in the ensemble mean, ranging from 1.5 to 6 degrees in the individual simulations, respectively. This simulated treeline shift is in agreement with pollen-based reconstructions from northern Siberia. The desert fraction in the transition zone is reduced by 21% during the mid-Holocene compared to pre-industrial due to enhanced precipitation. The desert-steppe margin is shifted westward by 5 degrees (1-9 degrees in the individual simulations). The forest biomes are expanded north-westward by 2 degrees, ranging from 0 to 4 degrees in the single simulations. These results corroborate pollen-based reconstructions indicating an extended forest area in north-central China during the mid-Holocene. According to the model, the forest-to-non-forest and steppe-to-desert changes in the climate transition zones are spatially not uniform and not linear since the mid-Holocene., Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe, 643

The large variety of atmospheric circulation systems affecting the eastern Asian climate is reflected by the complex Asian vegetation distribution. Particularly in the transition zones of these circulation systems, vegetation is supposed to be very sensitive to climate change. Since proxy records are scarce, hitherto a mechanistic understanding of the past spatio-temporal climate-vegetation relationship is lacking. To assess the Holocene vegetation change and to obtain an ensemble of potential mid-Holocene biome distributions for eastern Asia, we forced the diagnostic biome model BIOME4 with climate anomalies of different transient Holocene climate simulations performed in coupled atmosphere-ocean(-vegetation) models. The simulated biome changes are compared with pollen-based biome records for different key regions. In all simulations, substantial biome shifts during the last 6000 years are confined to the high northern latitudes and the monsoon-westerly wind transition zone, but the temporal evolution and amplitude of change strongly depend on the climate forcing. Large parts of the southern tundra are replaced by taiga during the mid-Holocene due to a warmer growing season and the boreal treeline in northern Asia is shifted northward by approx. 4 degrees in the ensemble mean, ranging from 1.5 to 6 degrees in the individual simulations, respectively. This simulated treeline shift is in agreement with pollen-based reconstructions from northern Siberia. The desert fraction in the transition zone is reduced by 21% during the mid-Holocene compared to pre-industrial due to enhanced precipitation. The desert-steppe margin is shifted westward by 5 degrees (1-9 degrees in the individual simulations). The forest biomes are expanded north-westward by 2 degrees, ranging from 0 to 4 degrees in the single simulations. These results corroborate pollen-based reconstructions indicating an extended forest area in north-central China during the mid-Holocene. According to the model, the forest-to-non-forest and steppe-to-desert changes in the climate transition zones are spatially not uniform and not linear since the mid-Holocene.

International audience; Rashid et al. (2016) questioned the use of the Mg-/Ca-based sea surface temperature (SST) data from the subpolar North Atlantic Ocean as well as the alkenone-based SST data from the western tropical Indian Ocean we used to reflect the winter SSTs or regional changes in the Holocene SSTs. We first would like to reemphasize that the main message we wanted to convey in our article is that the East Asian winter monsoon (EAWM) strength decreased and then increased again during the Holocene but with a substantial lag in southern China as compared to northern China. We, of course, wanted to back up our model results with published SST data that may have detected such an asynchronous variation in the EAWM. For convenience, we used a series of proxy records extracted from the extended Global database for alkenone-derived HOlocene Sea-surface Temperature (GHOST) database that were initially intended to provide a template of Holocene SST trends for model/data comparison purpose (http://doi.pangaea.de/10.1594/PANGAEA.737370). Rashid et al. (2016) questioned our model/data comparison exercise, arguing that the data we present in Zhang et al. (2015a) cannot be used to track leads and lags in winter SSTs in the North Atlantic and northern Indian Ocean. Below we address point by point the issues raised by Rashid et al. (2016) and thank the authors for giving us the opportunity to sharpen our model/data comparison analysis.

The problem such as parameters initialization and network structure determination is collectively referred to as the WNN optimization design. Aiming at the effect on the performance of WNN, an optimization design algorithm, which is based on Artificial Fish-Swarm Algorithm(AFSA), is proposed. The AFSA can synchronously determine the initial values of parameters and hidden layer nodes number in search space. The simulation results show it is an effective algorithm, which not only has higher accuracy and faster convergence rate but also can avoid the blindness of the WNN optimization design.

This article studies from structure of military supply chains, summarizes its risk origin, puts foreword a method of integrating case-based reasoning with the fuzzy technology, adopts the “case-express first fuzzy-reasoning second” reasoning mechanism to evaluate possible risk consequences in military supply chains. It is aiming at providing theory basis for conducting and developing military supply chain system.