Abstract:

The wind retransmission of seed is one of the key processes of the natural regeneration of Caragana korshinskii population in the artificial sand fixation forest in the desert， and its response law to the surface crust cover of the fixed sand is still unknown. In the southeast edge of Tengger Desert， 75%-100% （N₁）， 50%-75% （N₂）， 30%-50% （N₃）， 0-30% （N₄） crust covered and bare sandy land （Bs） were selected respectively， and the field wind tunnel experiment method was used to conduct a simulation study on the process of wind retransmission of different seed sizes. The results show that： The size of seeds and the coverage of crusts are the key factors affecting the wind retransmission of C. korshinskii seeds， and there are significant interactions between them. The seed wind retransmission is affected by the seed size， crust coverage and wind strength. The pattern of seed wind retransmission and diffusion generally presents the following rules： （1） With the increase of crust coverage， the seed retransmission distance increases gradually， while the probability of seed burial decreases gradually. When the crust coverage is 75%-100%， the maximum probability of seed long-distance transmission is 45.56%， the lowest probability of seed long-distance transmission resistance， and the probability of seed being buried is 0； When the crust coverage is 50%-75%， the maximum non-long-distance transmission probability is 73.33%； When the crust coverage is 30%-50%， the maximum probability of resistance to long-distance transmission of seeds is 62.22%； When the crust coverage is 0-30%， the probability of seeds being buried increases significantly； The lowest probability of long-distance transmission in bare sand is 5%. （2） With the increase of wind speed， the horizontal retransmission distance of seeds increases， and the smaller the seeds are， the farther their retransmission distance is， and the more likely the wind retransmission will occur； When the wind speed is higher than 13.6 m·s^-1， sand will be covered on the sample plots with low crust coverage， and the buried seeds will be transported again. （3） For the fitting of seed retransmission rate and distance， the fitting effect of middle seed retransmission rate and distance is the best， and its model is： y=-0.002x³+0.182x²-1.660x+4.084. To sum up， under the conditions of wind tunnel simulation experiment in the field， the seed size， soil crust coverage and wind strength can all affect the wind retransmission process of C. korshinskii seeds.

Key words: Caragana korshinskii, field wind tunnel test, seed size, wind retransmission, seed dissemination strategy