Effect of climate change on seasonal water use efficiency in subalpine Abies fabri

Abies fabri is a typical subalpine dark coniferous forest in southwestern China. Air temperature increases more at high elevation areas than that at low elevation areas in mountainous regions,and climate change ratio is also uneven in different seasons. Carbon gain and the response of water use efficiency(WUE) to annual and seasonal increases in temperature with or without CO_2 fertilization were simulated in Abies fabri using the atmospheric-vegetation interaction model(AVIM2). Four future climate scenarios(RCP2.6,RCP4.5,RCP6.0 and RCP8.5) from the Coupled Model Intercomparison Project Phase 5(CMIP5) were selectively investigated. The results showed that warmer temperatures have negative effects on gross primary production(GPP) and net primary production(NPP) in growing seasons and positive effects in dormant seasons due to the variation in the leaf area index. Warmer temperatures tend to generate lower canopy WUE and higher ecosystem WUE in Abies fabri. However,warmer temperature together with rising CO_2 concentrations significantlyincrease the GPP and NPP in both growing and dormant seasons and enhance WUE in annual and dormant seasons because of the higher leaf area index(LAI) and soil temperature. The comparison of the simulated results with and without CO_2 fertilization shows that CO_2 has the potential to partially alleviate the adverse effects of climate warming on carbon gain and WUE in subalpine coniferous forests.

The relationship between the Arctic Oscillation and ENSO as simulated by CCSM4

The correlation between the Arctic Oscillation （AO） and ENSO reflects the strength of the interaction between climate systems in the low and high latitudes. Based on the long-term （501 years） control simulation of CCSM4, the authors investigated the linkage between the AO and ENSO in boreal winter. Based on the correlation coefficients between them, the authors divided the entire period into two groups： one that included the years with statistically significant correlations （G1）, and the other the years with insignificant correlations （G2）. in G1, the AO-related atmospheric circulation pattern resembles the ENSO-related one. The Aleutian Low （AL） acts as a bridge linking these two modes, in G2, however, the AO and ENSO signals are confined to the mid-high and mid-low latitudes, respectively. There is no significant linkage between the AO and ENSO in boreal winter, showing a low correlation coefficient. Further analysis suggests that changes in the climatological features, including the strengthened AO, the negative Pacific Decadal Oscillation phase, and the weakened AL, may be responsible for the enhanced relationships.

Modeling Aerosol Climate Effects over Monsoon Asia:A Collaborative Research Program

This paper describes the latest progress of a collaborative research program entitled ＂Modeling Aerosol Climate Effects over Monsoon Asia＂, under the Climate Sciences agreement between the U.S. Department of Energy and the Chinese Academy of Sciences（in the early 1980 s, Professor Duzheng YE played a critical role in leading and formalizing the agreement）. Here, the rationale and approach for pursuing the program, the participants, and research activities of recent years are first described, and then the highlights of the program＇s key findings and relevant scientific issues, as well as follow-up studies, are presented and discussed.

Classroom Organization： from Teachers to Students

In the present article, the author looks into several influential questions that are too often given insufficient emphasis in the classroom teaching and the following conclusions are reached through the research： （1） Classroom is a behavior setting where students of different characteristics come to bring about desirable changes. Different strategies must be used to meet their needs; （2） Teachers are not just transmitters of knowledge; they must be an educator as well as a helpful person; （3） Students should be encouraged to communicate with teachers and their peers to achieve a conducive classroom climate.