Soil Seed Bank And Its Application In Vegetation Restoration In Coastal Area

This study aimed to characterize the soil seed banks (SSBs for short) of different types of eco-systems in Tianjin. Seven types of sample plots were selected according to an urban-suburb-rural-exurb gradient to research basic characteristics of soil seed banks and their potential applications in urban-greenland vegetation restoration. The sample plots included Nankai University (NU for short), Houtai (H), Wuqing Low-carbon Park (WLP), Guangang Forest Park (GFP), Binhai Wetland (BW), Jiyunhe hydro-fluctuation belt (JHB) and Baxian Mountain (BM).The research on basic characteristics of SSBs showed that storage of SSBs was very rich and the biodiversities were of high level, which laid the foundation for the application of SSBs in vegetation restoration of urban green space. The vegetation restoration research focused on possible ways and methods of using SSBs for vegetation restoration in urban green spaces of Tianjin. Main conclusions were as follows:(1) The storage of SSBs Banks of Tianjin was rich. The quantity and density of viable seeds were very significant, that were685-8803particles and3.65×105-4.69×106particles/m2. The order of seed density was:BW> GFP> NU> JHB> H> WLP> BM, and the order of woody plants’seeds was:WLP> GFP> BM> NU> H>BW>JHB.(2) The diversities of SSBs of Tianjin were distinct. In general, the diversity indexes of SSBs were lower than that of the ground vegetations. The species richness was14-42species. The Shannon.Wiener diversity indexes were1.000±0.775～2.649±0.139, while the Simpson ecological dominance indexes were0.453±0.361～0.888±0.019, and Pielou evenness indexes were0.422±0.300～0.793±0.037. These four indexes of Baxian Mountain were the highest, which indicated that Baxian Mountain was in the highest succession stage. Sorensen similarity indexes of SSBs and the ground vegetations were between0.248and0.621, ordering from big to small was:BW>GFP>NU>JHB>H>WLP>BM.(3) SSB had its access into vegetation restoration in urban greening. Combining its storage and diversity and the ecological function and value in vegetation restoration, the SSB possessed the property of important germplasm storage and natural resource. By summarizing the researches and practices about SSBs have been used in vegetation restoration and reconstruction, we accessed the demands of urban greening of Tianjin and found an access into green spaces by the method of vegetation restoration in the urban reconstructing, the suburb urbanizing, the coastal wetlands developing and road construction and so on. Compared to the disadvantages of traditional greening methods, using SSBs for vegetation restoration in urban green space could be of much more value, especially when consideration the biodiversity maintaining and indigenous plants conservation.(4) The effect of using SSBs in urban-greenland revegetation was remarkable. Using the SSBs of Wuqing Low-carbon Park as main material, we arranged an orthogonal test to revegetate on a bare urban-greenland, adopting the way of "ex situ restoration". There were three factors (the soil thickness, the coverage thickness and the quantity of tree seeds) and three levels of each factor. The results showed that the optimal combination of factors level should be A2B2C3(namely soil thickness was3cm, coverage thickness was3cm, and tree seed density was300particles per m2). Then an envaluation index system including11indexes was established to assess the results of vegetation restoration. The results showed that plot8had the optimal recovery effect, the combination of factors level was A3B2C1(soil thickness was5cm, coverage thickness was3cm, seeding density was100particles per m2), which had slightly difference with the range analysis results.(5) Soil seed germination experiment showed that the seeds germination presented germination rate-time curve, which formed "S" or "J" shape. Seed germination often started in a short period of3～7days, and reached the maximum germination rate after18～30days. Considering the community succession after the vegetation restoration expetiment, we found that the species richness index showed a trend of decrease; while the diversity indexes showed a trend of rise after the first reduce, which rosed to same level of that of ground vegetation after3years. The restored community coverage showed obvious seasonal change, coverage could reach90%in the growing season. The Sorensen similarity index of recovered community was low, while the community succession similarity index increased gradually. In conclusion, the community recoveried by SSBs obtained stable structure and the community succession reached a high stage after three years.