| The red soil hilly area is distributed in the tropical and subtropical areas of our country.Because of the intense human activities,the heavy rain and the high soil erotability,the primary vegetation primary vegetation once disappeared,which led to soil erosion,soil degradation and other environmental problems.Vegetation restoration and reconstruction is the fundamental way to control soil erosion,especially the natural restoration and natural regeneration of vegetation is the key to ecosystem restoration,regeneration and expansion;but long-term soil erosion has significantly changed the geomorphology and soil characteristics and restricted the regeneration and restoration of vegetation.As the material basis and key link of plant community renewal and species diversity maintenance,seed is the most sensitive stage of vegetation restoration One.Microecological changes caused by soil erosion will inevitably seriously affect the production,migration,loss,germination,survival,growth and colonization of seeds,and then affect the process and direction of vegetation renewal and restoration.In view of this,this paper takes Changting typical red soil erosion area as the research area,and selects the communities in different stages of non-vegetation restoration as the research object,through the continuous investigation of seed rain and seed bank in the community,explores the seed rain,seed bank and pattern in different restoration stage communities,reveals the relationship between seed rain,seed bank and aboveground vegetation,and discusses the influence of different soil erosion intensity on the sub-distribution of seed rain and seed bank after vegetation restoration.Whether there are sufficient and effective seeds in different restoration stage communities and the potential of seed rain and seed bank in the process of vegetation restoration and renewal in degraded red soil erosion area provide scientific basis for vegetation restoration and renewal in southern red soil erosion area.The results are as follows:1.Community seed rain characteristics:this experiment collected a total of 17 plant seeds,respectively belonging to 13 families 17 genera.Among them,the community species composition of feng shui forest and80 li river（no disturbance）with longer recovery time was the most,13species and 10 species,respectively;the community species composition of oil pit community from erosion bare land was the least,only 2 species;overall,with the increase of community recovery years,the number of community seed rain species tended to increase.In addition to erosion of bare land,tree species were dominant in seed rain in different recovery stages,accounting for more than 95%of seed rain in the community.As vegetation restoration progresses,the total rainfall density of community seeds is 3.3±0.8 from erosion of bare land the seeds·m-2increased significantly to 101.9±5.3 seeds·m-2,and the total seed rain density tended to stabilize in the community with longer recovery years.The peak period of seed rain in different restoration stages appeared before and after February,and the duration of the peak of seed rain in Fengshui forest and 80 li river community with long vegetation restoration years was longer.Although the number of intact seeds in seed rain in different recovery stages of the community is much larger than that of incomplete seeds,the seed vigor of seed rain seeds is obviously insufficient,especially the germination rate of seed rain seeds in the community of erosion bare land oil pit is only 3.3%.The results showed that the species that eroded the bare land and were in the early stage of vegetation restoration the number,seed rain density,seed vigor are all smaller than the communities with longer vegetation restoration time.in the early stage of vegetation restoration,there may be insufficient seed input.2.Community soil seed bank characteristics:the number and density of species in soil seed bank showed an increasing trend with the process of vegetation restoration,and the results of three sampling showed that the soil seed bank density of erosion bare land came to oil pit was the lowest.The species number and density of herbaceous plant seeds were absolutely dominant in each community,and the proportion of the density of herbaceous plant seed bank to the total density of seed bank reached more than 65%in different restoration stages.The vertical distribution of soil seed bank showed different regularity in different communities:the density of shallow soil seed bank was found in three communities:feng shui forest with long vegetation restoration time,80 li river（no disturbance）and youfang larger than the deep soil seed bank density,the overall performance is 0-2cm>2-5cm>5-10cm;whereas the vertical distribution law of the two communities with short vegetation restoration time is opposite,the soil seed bank is mainly distributed in 5-10 cm soil layer;because of the poor vegetation restoration,vegetation has insufficient ability to control soil erosion land,strong soil erosion makes the number of soil seed bank decrease,and soil seed bank presents deep distribution.3.Vegetation characteristics:With the progress of vegetation restoration,the species richness index in the community as a whole showed an increasing trend,but it increased slowly in the early stage of restoration.With the process of vegetation restoration,although the dominance of Masson pine has decreased in various plots,it is still the main species in the tree layer of each community.Except for the eroded bare-oil community,the species diversity index of each community is the largest in the shrub layer.4.Relationship between aboveground vegetation,seed rain and seed bank:the similarity index between aboveground vegetation,seed rain and seed bank did not show obvious regularity with the increase of vegetation restoration time,and the similarity index was low.The similarity index between seed rain and aboveground vegetation in each community was between 0.2～0.57,and the similarity index between soil seed bank and aboveground vegetation was between 0～0.43. |
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