Chin J Plant Ecol ›› 2009, Vol. 33 ›› Issue (3): 546-554.DOI: 10.3773/j.issn.1005-264x.2009.03.013

• Research Articles • Previous Articles     Next Articles

PLANT DISTRIBUTION IN FRESHWATER LAKESHORE: RELATIVE IMPORTANCE OF SPECIES POOL LIMITATION VS. NICHE LIMITATION

XU Yang1,2, LIU Wen-Zhi1, LIU Gui-Hua1,*()   

  1. 1Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, China
    2Graduate University of Chinese Academy of Sciences, Beijing 100049, China
  • Received:2008-07-02 Accepted:2009-02-09 Online:2009-07-02 Published:2009-05-31
  • Contact: LIU Gui-Hua

Abstract:

Aims Much research has focused on the effects of competition and stress tolerance on plant zonation in wetlands, but few studies have explored the role of propagule availability. This study examined the relative importance of niche limitation and species pool limitation in structuring lakeshore plant communities.

Methods We sampled the soil seed banks from the hygrophyte, emergent-plant and submerged-plant zones in a subtropical lakeshore marsh, Longgan Lake, China and used the seedling germination method to examine the density and species composition of seed banks. To assess the effects of species pool and water depth on community establishment, we exposed seed bank samples to three water-level treatments (depths of 0, 25 and 50 cm) and, 45 and 90 days later, compared the species richness and functional groups of the communities that established.

Important findings Species of the seed banks were grouped according to their ability to tolerate or respond to water-depth gradients. The established vegetations varied significantly among sites and treatments. For all three sites, mud-flat and emergent communities established at the 0 water-level treatment, while submerged communities established at the 25 and 50 cm water-level treatments, show-ing that the species belonging to different functional group have different tolerances to water depths and that water depth (niche limitation) was important in shaping plant zonation in freshwater marsh. Only the simplest community developed when the seed bank of the emergent-plant zone was exposed to the 25 and 50 cm water-level treatments, as well as when the seed bank of submerged-plant zone was exposed to the 0 water-level treatment. This shows that community species richness depends primarily on the composition and viability of the seeds in the soil seed bank. These findings suggest that the structure and distribution pattern of the wetland community were determined by both niche limitation and species pool limitation. Their relative importance may depend on the stability of the water regime.

Key words: marsh vegetation, niche, seed bank, zonation distribution, water level