Characteristics of soil seed bank for Solanum rostratum Dunal. and its response to control with replaceable plants

Soil seed bank is important in the restoration and succession of vegetation in degraded ecosystems. In order to determine the characteristics of soil seed bank of the alien invasive plant Solanum rostratum Dunal. and to evaluate the effects of replacement control of S. rostratum, soil seed bank of S. rostratum in two typical habitats (riverside and farmland margin) were studied and its' vertical distribution and seasonal dynamics analyzed. In addition, a study on replacement control of S. rostratum was conducted using varieties of perennial forages of Gramineae and Leguminosea. 1) Based on the results, 23 plants species were identified, and Gramineae and Compositae were the most dominant families. The total reserve of S. rostratum seed banks in the riverside and farmland margin were respectively 347 seeds·m^-2 and 2 600 seeds·m^-2, which accounted for 2.46% and 35.16% of the whole seed bank. S. rostratum was the dominant family in farmland but another invasive plant (Cenchrus spinifex Cav.) was the main species in riverside; reaching 5 187 seeds·m^-2 and accounting for 36.70% of the seed reserve. 2) S. rostratum seeds were mainly stored in the 0-2 cm soil layer in riverside region, accounting for 64.3% and decreasing with increasing soil depth. There was no significant difference in the three soil layers of farmland margin in terms of S. rostratum seed reserve (P>0.05), which accounted for 32.7% (0-2 cm), 38.2% (2-5 cm) and 29.1% (5-10 cm) of the total seed bank. However, it was need to pay attention to potential hazards of seeds in the middle and lower layers (2-10 cm). 3) For the three times of samplings, S. rostratum seeds mainly were collected in April reached 273 seeds·m^-2 and 1 970 seeds·m^-2 in riverside and farmland margin, significantly fewer in June and August. 4) In the second year of the controlled replacement, the coverage of forage gradually increased, the resources and niches were seized by the forage, and the growth of S. rostratum significantly inhibited. The density, biomass and soil seed reserve of S. rostratum were controlled at a low level, significant lower than CK (P < 0.05). Astragalus adsurgens Pall., Festuca arundinacea Schreb., Agropyron cristatum (L.) Gaertn., combined with Leymus chinensis (Trin.) Tzvel. had the best control effect on S. rostratum. At the same time, it showed obvious economic benefits, which produced forage grass of 20 396.1 kg·hm^-2 (fresh weight) and 7 710.6 kg·hm^-2 (dry weight). 5) Soil seed reserves of S. rostratum was positively correlation with density (P < 0.01) and biomass (P < 0.05) of S. rostratum, while forage yield was negatively correlation with soil seed reserve, density and biomass of S. rostratum. However, this was not significant (P>0.05). Nevertheless, rainfall significantly affected soil seed reserve of S. rostratum (P < 0.05), which was described by the power function model y=2.619x^0.001 (R²=0.822, F=18.486, P=0.013). Therefore, plant replacement combined with physical and chemical methods can be used to establish integrated system to control S. rostratum growth in habitats such as grassland, farmland margin and wasteland.