引种植物水桦在三峡库区消落带的种子萌发及生长特性

The Seed Germination and Growth Characteristics of Introduced Plant Betula nigrain Hydro-fluctuation Belt of Three Gorges Reservoir Area

【目的】观察研究水桦(Betula nigra)种子在三峡库区消落带的萌发及生长特性,为科学评价引种植物水桦在三峡库区消落带的适应性奠定基础。【方法】在重庆市万州区壤渡镇、开州区澎溪河湿地自然保护区、忠县石宝寨镇、奉节县竹衣河等地高程为170,175,178m的消落带区域分两次播种水桦种子,研究不同土壤类型、高程对种子累计萌芽率、存活率的影响,调查水桦株高、地径、冠幅、开花结实情况并测定水桦光合参数。【结果】1)在不同的土壤条件下种子萌芽力不同。2)种子萌发后当年存活率较高,但淹水出陆后全部死亡。3)两年生水桦种植在消落带在高程170,175m处2年后始花,但开花结实数少,果实不能自然萌发;种植4年后两处水桦的株高分别为6.22,6.95 m,两者差异具有统计学意义(p<0.01)。4)消落带春季出陆后,在170 m高程处的水桦净光合速率日均值逐渐增强,至秋季蓄水前期达23.10μmol·m-2·s-1;在高程175m处的水桦净光合速率日均值为14.64μmol·m-2·s-1;两者差异具有统计学意义(p<0.05)。【结论】水桦在消落带的种群个体数量不能自然增长,初步判断该物种不具有生态入侵性;冬季淹水时间长短对水桦生长有明显影响,但水桦可通过增强光合能力来适度补偿长时间淹水的影响,以达到适应三峡库区消落带这一特殊生境的目的。

[Purposes]In order to scientifically evaluate the adaptability of introduced piant Betula nigra in hydro-fluctuation belt of Three Gorges reservoir area, the germination and growth characteristics of t3. nigra seeds were observed. [Methods] Betula nigra seeds were sowed two times in the Rangdu town of Wanzhou district, Pengxihe wetland nature reserve of Kaizhou district, Shibaozhai town of Zhongxian county, Zhuyihe of Fengjie county in Chongqing city. The effects of different soil types and elevation on the seed cumulative germination rate and survival rate were studied. Plant height, ground diameter, crown width, flowering and fruiting were investigated, photosynthetic parameters were measured. [Findings]1）B. nigra＇s seed germination under different soil conditions was different. 2）The survival rate of Betula nigra after seed germination was high, but all died after flooding. 3）Biennial seedling of B. nigra bloomed after two-year growth, but the number of flower and fruit was small. There＇s no seed germinated and no plants grew after the fruit dropped. The height of B. nigra which planted on the hydro-fluctuation belt of elevation 170 m and 175 m was 6.22 m, 6.95 m after four-year growth. There was a significant difference （p〈0.05）. 4） The daily mean net photosynthetic rate of 13. nigra at the elevation of 170 m increased gradually after outcrop in spring. It can increase up to 23.10 μmol · m^-2 · s^-1 in storage period in autumn. It was significantly higher than it in the elevation of 175 m （14.64 μmol · m^-2 · s^-1） （p（0.05）. [Conclusions]B. nigra＇s individual species can＇t grow naturally. Introduced plant 13. nigra which planted on the hydro-fluctuation belt of Three Gorges reservoir don＇t have ecological invasion by preliminary judgment. The length of flooding time in winter has a significant influence on the growth of B. nigra. But B. nigra can enhance photosynthesis ability to compensate the long-time effects of flooding on plant growth and finally it can adapt to the special environment of the anti-season flooding in hydro-fluctuation belt of Three Gorges reservoir area.