Caragana microphylla is one of the key species for vegetation restoration in Horqin Sandy Land. Adopting field investigation and outdoor experiments,the microclimate effect of artificial C. microphylla communities with different restoration years were studied by observing wind velocity,air temperature,relative humidity and soil temperature. The results show that:( 1) Caragana microphylla community has an obvious wind-breaking effect near ground surface. Compared with shifting dunes,the wind velocity in the 6-year-old and 11-year-old C. microphylla shrubs at the height of 30 cm separately decreases by 71. 9% and 76. 0%.( 2) Mean daily temperature in the 6-year-old and 11-yearold C. microphylla communities is 3. 7 ℃ and 4. 9 ℃ lower than in shifting dunes,respectively.( 3) The relative humidity of air in the Caragana microphylla shrubs is higher than in shifting dunes.( 4) Soil temperature in C. microphylla plantation is lower than in shifting dunes. These results are significant in further exploring material and energy exchange near surface layer of artificial vegetation in the extremely arid condition.
Social vulnerability evaluation is of important significance to analyzing risks of natural disasters to human society and economy. By using expert investigation and AHP method,12 indicators from four aspects( population,economy,infrastructure and disaster prevention and mitigation capacity) are selected to assess social vulnerability to natural disasters on a county scale in Henan Province. The results show that the population vulnerability and economic vulnerability to natural disasters in the eastern region is generally higher than in the western region,while the areas with high infrastructure vulnerability are mainly located in the northwest; the disaster prevention and mitigation capacity in northwest is higher than in east and south,and this capacity of various districts is obviously higher than that of counties; in terms of the spatial pattern,social vulnerability to natural disasters is roughly higher in a belt from northeast to southwest,and lower on both sides of the belt. The results can provide scientific basis for disaster risk management and disaster prevention and mitigation planning in Henan Province.
