Characteristics Of Soil Seed Banks In A Typical Steppe In The Loess Hilly Region Of Ningxia Under Different Ecological Restoration Measures

Soil seed bank is the basis of vegetation renewal on the ground and plays an important role in vegetation succession restoration and community diversity maintenance.The hilly area of Loess Plateau is a key area for ecological construction of the two pinghe three belts in China.We investigated the germination dynamics,density characteristics,species diversity,similarity to the above-ground vegetation of the soil seed bank and the characteristics of seed and soil factors in correspondence analysis modelunder different restoration measures in a typical steppein Ningxia,aimed at the grassland ecological construction and soil seed bank study provides the basis.We selected the sites that has been subject to enclosure,contour trench and fish-scale pits for 0 year(1 year),3 years,6 years,10 years,15 years.The results showed that:(1)The seed sizes of soil seed banks in typical grassland areas were mostly between 0.25 and 2 mm,and the soil samples could be concentrated by 2 mm pore size soil sieve to reduced the working intensity of seed bank germination.(2)Typical savanes soil seed Banks in 0? storage 30?35 d after germination,could obtain higher density of soil seed bank.(3)Seed germination peak of soil seed bank in typical grassland area were about 2 weeks,and 90%seed quantity could be obtained within 30 days of seed bank germination.(4)Compared with grazing,the number of plant species in the soil seed bank can be increased by the measures of fish-scale pits,contour trench and enclosure.The most obvious measures for the restoration of 3 years were the enclosure and contour trench,6 years were the most obvious,10 years were the most obvious,and 15 years were the most obvious.The highest number of species were planted in 15 years of enclosure,3 and 6 years of fish-scale pits reclamation and 3 years of contour trench reclamation.(5)The seed vault plants were mainly perennial plants,among which compositae,gramineous,rosaceae and cruciferae were the main species of seed vault.(6)Compared with grazing,the density of soil seed bank increased to some extent under the measures of enclosure,contour trench and fish-scale pits.With the increase of the recovery period,the density of seed bank of sealed grassland was the maximum with F6 treatment,the maximum with S15 treatment in contour trench and the maximum with Y3 treatment in fish-scale pits.Under the similar rehabilitation period,the measures of fish-scale pits in 3 years were the biggest,those of 6 and 10 years were the biggest,and those of contour trench in 15 years were the biggest.The seed distribution of soil seed bank has surface aggregation.(7)With the increase of the recovery period,there was no obvious change in soil seed bank richness,dominance,diversity and evenness index of typical grassland.The dominant species of aboveground vegetation and soil seed bank were not consistent under different treatments.The similarity between seed bank and overground vegetation is generally low.(8)CCA showed thats oil bulk density,soil available potassium and soil available nitrogen were the main factors affecting the distribution of soil seed bank in this area.