Summer Dormant Buds Composition And Its Response To Flooding Of Wetland Dominant Plants In Poyang Lake

Wetland supports high abundance of animal and plant resources with the reputation of "the kidney of the earth". Wetland plant is the primary producer of wetland ecosystems. Belowground bud bank is one of the main reproduction strategies. It plays a key role in the maintenance of plant species diversity and vegetation succession. Therefore, wetland bud bank has attracted lots of concerned. With better understanding the characteristics of wetland bud banks and its responses to water level changes, we can better predict the responses of shoreline vegetation to water level fluctuations in the wetlands of Poyang Lake, and provide scientific basis for wetland ecosystem management. The aims of this study were to investigate the characteristics of bud banks for dominant wetland vegetation species in Poyang Lake and the germination of the buds under different water conditions. Main results are as follows.(1) There are 6 families, 11 genera and 12 species of plants investigated in the belowground bud banks. All these species are perennial aquatic plant species. Most of the species was composed of Gramineae, Cyperaceae and Hydrocharis dubia, plants mainly regenerated by rhizomes. The bud bank density was 235.28 ± 57.91(individual. m-2). The buds of Carex cinerascens and Phalaris arundinacea were the dominant species.(2) We also determined the morphological characteristics and the vertical distribution of belowground bud bank for dominant species of Poyang Lake.(1) Bud density decreased with soil depth and it was greatest at 0-10 cm soil.(2) The length of buds decreased with soil depth and was greatest at 0-10 cm soil and least at 20-30 cm.(but bud length of C. cinerascens was greatest at 10-20 cm soil) Although buds of different species usually differed in morphology, but also have some common traits: t most plant buds originate from roots, stems, or both the two organs. But species differed in the morphology of rhizome, position and the growth direction of the buds.(3) We also carried out indoor germination experiment. Bud germination rates were different among dry, wet and water logging water condition treatments. Water logging decreased the bud germination. For most species, the rank of germination rates under different water condition is wet condition > dry condition > water logging condition.Conclusion: in the Poyang Lake, belowground buds of wetland plants showed high diversity in morphology. Species were differed in the bud morphology and bud distribution at different soil depth. The bud germination rate was greatest at wet condition and lowest at water logging condition. At the same water condition, the germination rates were differed among different species.