Relationship Between Soil Seed Bank and Aboveground Vegetation Along an Altitude Gradient in the Jiangjia Gully

We established 8 elevation gradients at 200 m intervals in the altitude range of 1300–2900 m in Jiangjia Gully and surveyed the species composition, species diversity and similarity of soil seed banks and vegetations at different altitude gradients. The results showed that species numbers of vegetation were significantly higher than that in the soil seed bank at each altitude gradient. There were lower similarities between vegetation and soil seed banks. There was incomplete synchronization in the dominant species between vegetation and soil seed bank. The vegetation was dominated by perennial herbs except in 1700–1900 m and 1300–1500 m, while the soil seed banks were dominated by perennial herbs only in areas above 2300 m. The soil seed bank in the Jiangjia Gully watershed had a weak ability to recover naturally and regenerate the vegetation. The Margalef richness index, Simpson dominance index and Shannon−Wiener diversity index of soil seed banks and vegetation were significantly positively correlated. The Pielou uniformity index of the soil seed banks was significantly higher than that of the vegetation. The highest values of M, D and H of vegetation and soil seed bank occurred in the temperate humid mountain climate zone, while the lowest value occurred in the subtropical dry-hot valley climate zone, indicating that the difference of hydrothermal conditions in different climate zones may affect the species diversity of vegetation and soil seed bank. The soil seed bank and vegetation were greatly affected by climate change, but they do not respond significantly to the changes of elevation gradients. The results also can provide a theoretical basis for ecological restoration and reconstruction in the watershed of Jinsha River.