Temporal And Spatial Characteristics Of Seed Rain In Artificial Caragana Korshinskii Forest At Different Years Of Sand Fixation In The Tengger Desert

Seed rain is the key link of community renewal and development,and also a vivid description of plant seed dispersal.To explore caragana korshinskii,population and community characteristics of seed rain,this study tengger desert the southeast margin of artificial caragana korshinskii Lin as the research object,using the method of continuous fixed-point observation,for different sand-fixation fixed number of year(65 a,59 a and 30 a)caragana korshinskii community,the number of different crown caragana korshinskii seed rain,composition and distribution process and spatial distribution pattern,The diffusion law of seed rain and the relationship between seed size and dispersal capacity of artificial Caragana korshinskii forest were analyzed.The main results were as follows:(1)The seed rain quantity of large crown(1634.65 seeds·m-2)>medium crown(884.26 seeds seed·m-2)>small crown(417.00 seeds seed·m-2);The seed rain vigor of large crown(75.00%)>medium crown(72.72%)>small crown(68.82%).(2)Seeds of 16 species of 13 genera and 6 families were found in seed rain of artificial Caragana korshinskii forest community.The amount of seed rain was 3580.59 seeds·m-2>2920.37 seeds·m-2>2467.09 seeds·m-2 in the sand-fixing 40a caragana korshinskii forest plot.A total of 11 species of plants belonging to 10 genera and 3 families were found in the above-ground vegetation of artificial caragana korshinskii forest,mainly annual herbaceous plants.The similarity between seed rain and aboveground vegetation in sand-fixing 40a caragana korshinskii plantation(86.96%)>20a caragana korshinskii plantation(80.00%)>60a caragana korshinskii plantation(72.00%).(3)The seed rain of caragana korshinskii showed a single peak pattern,which began to spread in late may.After that,the amount of seed rain gradually decreased and ended on August 25.The duration of seed rain was about 100 days.The seed rain distribution of artificial caragana korshinskii forest showed a "double peak" pattern,with the peak in July and November.(4)The seed rain distribution area of caragana korshinskii per plant was proportional to the crown width,and the seeds were mainly distributed in the west and north side of the plant.The seed rain of artificial caragana korshinskii forest community was affected by topography,and the vegetation was uneven,which resulted in spatial heterogeneity of seed distribution.The dispersability of caragana korshinskii seed decreased with the increase of seed size.In conclusion Caragana korshinskii did not show aging phenomenon,but still had high sexual reproduction ability.With the increase of sand fixation years,the number and species of seeds in caragana korshinskii forest increased linearly and then decreased,and the potential regeneration capacity and stability of the community were stronger in the plot with 40 years of sand fixation years,which was the highest The community was in positive succession at the initial stage of restoration,and degraded to a certain extent at the later stage of restoration.