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.
Soil seed banks can provide a mechanistic for understanding the recruitment dynamics and can inform conservation management of ecosystems. To investigate the contribution of soil seed banks to vegetation restoration in moving sand dune systems, we compared seed structure and species similarity between soil seed banks and standing vegetation among moving sand dunes, ecotones and dune slacks in northeast China. Average seed density in dune slacks was greater than in ecotones or moving sand dunes. Seed density in the soil layer of 0-10 cm was greater than at 10-20 cm both in the moving sand dunes and the eco- tones, but seed densities were similar at depths of 10-20 and 20-30 cm in moving sand dunes. Moreover, the spatial autocorrelation of seed density on moving sand dunes was weak but was strong on the ecotones and dune slacks. The species in the soil seed bank of moving sand dune systems were nearly all annuals, and the low similarity was mainly due to the lack of perennial species that were common in standing vegetation. Consequently, vegetation restoration cannot mainly rely on the soil seed banks in the movingsand dunes and more attention should be paid to protection of the dune slacks because they are the main source of seed disperse and seedling recruitment in moving sand dune systems.
