青藏高原东部尕海湿地种子库沿水位梯度的分布格局

Abstract

In recent years, wetland biodiversity and vegetation on the Qinghai-Tibet Plateau have been severely degraded. The seed bank is one of the most important resources available to aid recovery of degraded wetland plant communities. Studies of seed bank heterogeneity are crucial for understanding population formation, vegetation succession, and dynamics. In this study, we investigated the seed bank along water gradients of the Gahai Lake wetland on the eastern Qinghai-Tibet Plateau. We established three sampling lines in lakeside zones and two sampling lines in submerged zones, and looked for differences between lakeside and submerged zones. Seed bank species number and evenness were the same among different sampling lines and different zones, whereas Shannons ( H ) and Simpsons ( D ) formulas revealed that diversity was higher in the lakeside zone than in the submerged zone. A comparison based on Sorensens index indicated the least diverse along the first sampling line. DCA and TWINSPAN analyses separated the sampled species into two clusters: a group consisting of the first and second sampling lines and the first sample of the third line, and a group comprising the remaining samples. Based on species rarefaction curves, more species were found to occur in submerged zones than lakeside zones, although frequency of presence of species found in both zones was similar. Comparisons of species life histories and plateau endemicity revealed that the number of endemic species in the fourth and fifth sampling lines was higher than in the first three lines. Our results indicate that a vegetational zonation pattern based on water gradients exists around Gahai Lake.