Dominant Patterns of Summer Rainfall Anomalies in East China during 1951-2006

The dominant patterns of summer rainfall anomalies in East China were studied using Empirical Orthogonal Function （EOF） analysis. The results indicate that after the late 1970s, the first and second dominant patterns switched. During the period before the late 1970s, the spatial pattern of the first （second） dominant mode was the ＂Yangtze River pattern＂ （the ＂South China pattern＂）, but this changed to the ＂South China pattern＂ （the ＂Yangtze River pattern＂） after the late 1970s. This decadal change in the dominant patterns resulted from a significant decadal change in summer rainfall over South China after the late 1970s, i.e., a negative phase during 1978-1992 and a positive phase during 1993-2006. When the decadal variation of rainfall in East China is omitted from the analysis, the first and second dominant patterns represent the ＂Yangtze River pattern＂ and the ＂South China pattern＂, respectively. These results suggest that when decadal variation is included, the rainfall in China may be dominated by one mode during certain periods and by another in other periods. For the interannual variability when decadal variation is excluded, however, the first and second modes can be easily distinguished, and their order has been stable since at least 1951.

Diversity and dominant species of arthropods in different forests of Aershan,Inner Mongolia

Taking different forests in Aershan of Inner Mongolia as sample plots, diversity and dominant species of arthropods were studied. The results show that two classes, 17 orders, 68 families, 130 species and 3742 individuals were identified and 92.31% of total species appeared in natural forests, and 75.38% of total species appeared in plantations. The orders of Lepidoptera, Coleoptera, Diptera and Hymenoptera covered most of the collected arthropods. In different forest types, diversity indices is natural mixed forests （Betula platyphylla x Larix gmelinii）〉 natural pure B. platyphylla forests〉natural pure L. gmelinii forests〉plantations with pesticide treatment〉plantations without pesticide treatment. In natural forests, more than 70% of the arthropod families, species and individuals were distributed in shrub and herb layer, while in plantations 75% of the arthropod families, 78% of species and 80% of individuals were also distributed in shrub and herb layer. Lepidoptera, including Loxostege sticticalis （Linnaeus）, Chilo suppressalis （Walker） and Lymantria dispar （Linnaeus）, had the highest dominant degree.