西南桦造林技术

西南桦又名桦桃树、野樱桃等，树体高大，于形通直，尖削度小，材质细致优良，适应性广，生长迅速，是次生林改造林区的先锋造林树种和重要的用材树种。西南烨在我省主要分布于文山、红河、思茅、西双版纳、临沧、德宏、保山等地州县及玉溪市南部各县，最低海拔可至２００米，最高海拔可达２５００米以上。分布区常呈群状生长，或形成小片生长。近川年来，西南烨造林被提到了重要位置。但由于未掌握西南桦造林技术，往往造成采种育苗不见苗、造林成林不成材，甚至造林失败，严重影响了西南烨的造林进程。为此，腾冲县林业局沙坝林场的科技人员从１９９２年开始，专题研究西南烨的造林技术，取得了可喜的成绩，掌握了一套切实可行的西南桦营林技术。

蜂窝纸容器山地育苗方法

一、选地与整地1.选地为了缩短松树苗木运输距离,保持苗木的完整性,提高造林成活率,育苗地应选在近造林地、地势较平缓、土层深厚、水源条件好的荒山荒地。2.整地把山地沿等高线挖成水平台地,宽为2米左右。

Effectiveness of Soil Conservation Methods in Preventing Red Soil Erosion in Southern China

Rainfall, runoff(surface runoff and interflow) and soil loss were recorded from 2002 to2005 in an experiment with four treatments on sloping red soil land in southern China. Treatments consisted of bare sloping ground(control check, CK),interplanting with soybean in spring or radish in autumn(I), level terrace(i.e., grass planted on the riser and bunds built at the edge of a bench terrace)(II), and level terraces of orchards with Bahia grass planted on the riser(III). The surface runoff and erosion in treatment II and III during the four years were low despite the occurrence of potentially erosive rains. By contrast, the CK plot had both the highest surface runoff coefficient and the highest sediment yield among all the plots. The surface runoff and soil erosion of the CK plot significantly differed from that of the treatment plots(p < 0.05). Additionally,Significant differences between the interflow of the CK plot and that of the treatment plots was found from April to August(p < 0.05). However, no significant differences between the CK and treatment plots were found from January to March and September to December. The order of the plots in terms of surface runoff coefficients and soil losses was: CK > I > III > II, whereas their order in terms of interflow was II > III > I > CK. The effects of treatment II were excellent, indicating that level terrace(i.e., grass planted on the riser and bunds built at the edge of a bench terrace) can be an excellent practice for soil and water conservation on sloping red soil land. Soil loss in southern China can be reduced through the widespread use of this approach.

Changes of Terrestrial Water Storage in River Basins of China Projected by RegCM4

In this study, a historic simulation covering the period from 1951 to 2000 and three projected scenario simulations covering 2001-2050 were conducted em- ploying the regional climate model RegCM4 to detect the changes of terrestrial water storage （TWS） in major river basins of China, using the Intergovernmental Panel on Climate Change （IPCC） Special Report on Emissions Scenarios （SRES）： A1B, A2, and B1. The historic simula- tion revealed that the variations of TWS, which are dominated by precipitation in the basins, rely highly on their climatic features. Compared with the historic simu- lation, the changes of TWS in the scenario simulations showed strong regional differences. However, for all sce- narios, TWS was found to increase most in Northeast China and surrounding mountains around the Tibetan Plateau, and decrease most in eastern regions of China. Unlike the low seasonal variations of TWS in arid areas, the TWS showed strong seasonal variations in eastern monsoon areas, with the maximum changes usually oc- curring in summer, when TWS increases most in a year. Among the three scenario simulations, TWS increased most in Songhua River Basin of B1 scenario, and de- creased most in Pearl River Basin of A2 scenario and Hal River Basin of A1B scenario, accompanied by different annual trends and seasonal variations.

Study on the Seismic Fortification Criteria of Offshore Platforms in the Bohai Sea

This paper analyzes the seismicity and seismic risk distribution in the Bohai Sea. Based on the seismic design parameters of 46 platforms in the Bohai Sea, a statistic analysis is made on the ratios of the peak accelerations for different probability levels. In accordance with the two-stage design method, a scheme of two design seismic levels is proposed, and two fortification goals are established respectively for strength level earthquakes and ductility level earthquakes. Through analogy and comparison to the Chinese seismic code for buildings, it is proposed that the probability level for the strength and ductility level earthquakes takes return periods of 200a and 1000～2500a respectively, and we further expounded on its rationality. Finally, the fortification parameters in the sub-regions of Bohai Sea area are given in the light of seismic risk zonation and ground motion division. This article is a summary of experiences from many years of offshore platform seismic fortification work, and an exploratory study on the seismic fortification standards of offshore platforms in China, which may provide some references for the establishment of the standard.