Trends in sunshine duration and atmospheric visibility in the Yunnan-Guizhou Plateau,1961-2005

Using the observed data from 184 stations over the Yunnan-Guizhou Plateau （YGP） from 1961 to 2005, the long-term trends in sunshine duration, cloud amount, dry visibility （Vd）, dry extinction, and water vapor over the YGP are analyzed. The results show that 85% of the stations recorded shortening annual sunshine duration, with the decrease rates between -12.2 and -173.7 h/10yr. Results of Mann-Kendall tests indicate that, among the stations with decreasing sunshine duration, 63.7% of them experienced an abrupt change that started in the 1970s and peaked in the 1980s. This decreasing trend has reversed in the early years of the 21st century. The cloud cover and water vapor content in the mid and lower levels over the YGP had no obvious changes during the study period. The annual averages of Vd declined from 34 km in the 1960s to 27 km at present. The annual mean dry extinction coefficient trended upward, from 0.176 to 0.190, on the YGP from 1980 to 2005. Analyses of cloud cover, water vapor, atmospheric visibility, and dry extinction coefficient revealed that emitted tropospheric aerosols （including air pollutants） resulting from increased energy consumption over the YGP could be a major Factor influencing the reductions of sunshine duration and atmospheric visibility.

Spatial association between landslides and environmental factors over Guizhou Karst Plateau,China

Guizhou Karst Plateau is located at the center of the karst region in Asia, where landslides are a typical disaster. Affected by the local karst environment, the landslides in this region have their own characteristics. In this study, 3975 landslide records from inventories of the Guizhou karst plateau are studied. The geographical detector method is used to detect the dominant casual factor and predominant multi-factor combinations for the local landslides. The results show that landslides are prone to areas on slopes between 10° and 35°, of clay rock, in close proximity to gullies, and especially in areas of moderate vegetation, dryland, and mild rocky desertification. Continuous precipitation over 10 days has a great effect on landslide occurrence. Compared with the individual factors, the impact of two-factor interaction has greater explanatory power for landslide volume. The volume of earthquake-induced landslides is predominantly controlled by the interactions of faults and slopes, while that of humaninduced landslides is affected by the interactions of land cover and hydrological conditions. For rainfallinduced landslides, the dominant interactions vary in different regions. In the central karst basin, the interactions between faults and precipitation can explain over 90% of the variations in landslide volumes. In the southern hilly karst region, the interactions between lithology and slope can explain over 71% of the variations in landslide volume and those between fault and land-use can explain 50% of the variations of the landslide volumes in the northeastern mountainous karst region.

Analysis of Meteorological Condition for Infection of the Pathogen of Tobacco Brown Spot (Alternaria alternate)

[Objective] The paper was to understand the suitable meteorological indexes and key meteorological factors for infection and prevalence of tobacco brown spot. [ Method] Tobacco brown spot disease in five topical mountainous climatic areas of Guizhou Province was investigated, and the difference of biological characteristics of different strains was analyzed indoor. Different meteorological conditions （light, temperature and humidity） were simulated in artificial climate box by using the uniform design method, and the difference of infection ability of Alternaria alternate in different climate zones was analyzed in leaves in vitro by hanging drop method. [ Result] The infection rate of A. alternate in different climate zones of Guizhou Province showed certain difference. In low temperature and mid- die humidity （the humidity is 50% -60%, the temperature is 10 -20 ℃） conditions, the pathogen could infect tobacco leaves, various strains had certain difference, but the difference was small. [ Conclusion] The paper provided theoretical basis for prevalence prediction and control of tobacco brown spot.