Effects of altitude and slope aspect on soil seed banks on natural steep slope of Funiu Mountain, Henan Province of central China

  Objective  Soil seed bank acts as a propagule source for revegetation to affiliate the restoration of degraded lands. The aim of this study was to investigate the responses of soil seed banks to altitude and slope aspect on natural steep slope and the relationship between soil seed banks and aboveground plant communities.

  Method  Plant community investigation and soil seed bank collection were carried out on the shady and sunny slopes of the natural steep slope of Funiu Mountain, Henan Province of central China at an altitude of 600, 800 and 1 000 m. Then, soil seed bank composition and density, species diversity and richness of soil seed banks were estimated using the germination method.

  Result  (1) Aboveground plant communities contained the number of 67 species and Fagaceae species was in the majority. A total of 62 species were identified in the soil seed banks and dominated by herbaceous species, which accounted for 82.26%, much higher than woody species. The species of Compositae occupied the largest proportion (24.19% of the total), followed by Gramineae and Caryophyllaceae (9.68% and 9.68% of the total, respectively). (2) The seed density was between 1 263 and 10 363 grain/m², among which Cyperaceae seeds had the highest reserves, followed by Compositae and Gramineae. In terms of the reserve vertical structure, soil seeds were mainly distributed in 0−5 cm layer rather than 5−10 cm layer. (3) Species richness of arbor and shrub layer was positively correlated with altitude (P < 0.05), while herb layer species richness was negatively correlated with slope aspect (P < 0.05). In addition, there was positive correlation between seed density and altitude and slope aspect (P < 0.05). (4) The species composition of soil seed bank and aboveground plant communities showed relatively large differences with only 17 species in common and low species similarity coefficient ranging from 0.08 to 0.21. However, herb layer and soil seed banks displayed higher species similarity, and the structure of arbor layer and shrub layer appeared to provide certain explanations for the characteristics of seed banks.

  Conclusion  We conclude that the species diversity of aboveground plant communities and soil seed banks generally increase with altitude. Characterized by the highest seed density and species diversity, soil seed banks on the sunny slope at an altitude of 1 000 m possess strong potential for vegetation restoration.