【摘要】 为了分析大米草(Spartina anglica)在中国海岸带衰退过程中对潮汐淹没时间的生态适应性,通过人工模拟潮汐控制试验,对不同潮汐淹水时间处理(淹水时间分别为每天2 h,4 h,6 h,8 h和10 h)条件下大米草叶片的脯氨酸含量、可溶性糖含量、叶绿素含量和光合速率等生理指标及总生物量的影响进行研究。结果表明,随着淹水时间的延长,大米草叶片可溶性糖、光合速率及总生物量呈增加趋势,淹水6 h后又呈下降趋势,各指标均在6 h淹水时间处理条件下最大,显著高于其他处理(p<0.05);而叶片脯氨酸含量从淹水4 h后,呈现显著增加趋势,淹水10 h时达到最高;淹水处理对叶片叶绿素b及叶绿素c含量影响显著,分别以淹水时间4 h叶绿素b含量和10 h时叶片叶绿素c含量最低,而对叶绿素a及叶绿素a/b值的影响无显著差异。综合分析大米草的生理指标对模拟潮汐淹水时间处理的适应性,推断大米草种群较适宜的潮汐淹水时间为6 h/d左右,而由于大米草在中国沉积型海岸带分布区高程的变化使大米草种群长期不能达到最适淹水时间,是大米草种群自然衰退的主要原因之一。更多还原

【Abstract】 Environmental factors,especially waterlogging influence the plant distribution and zonation in coastal salt marsh.Waterlogging affects plant growth and distribution because soil inundation and partial(or total) submergence of vegetation drastically affects gas exchange in both plant and soil.Spartina anglica is an important grass inhabiting in the inter-tidal area for it enables enhanced metabolic efficiency and facilitates internal oxygen transport by means of root aerenchyma.The physiological responses to waterlogging time of coastal plants are important part in wetland ecology.Effects of simulated tidal waterlogging time on the physiological responses of Spartina anglica were investigated in the glasshouse with population coming from the Xinyang Harbor in Jiangsu Province,China.In April 2006 S.anglica plants were collected from sites of Xinyang Harbor in Jiangsu Province,China(33°37.8′N,120°34.6′E,).Individual ramets,each consisting of a single tiller with attached roots,were separated.Then similar-sized ramets(6.0±0.5) cm high were selected and planted into pots(26 cm in diameter and 21 cm in height),containing 15-cm-deep sand and loam mixture at a volume ratio of 1∶1.The pots were placed into the trays.5 treatments were set up with 2 h,4 h,6 h,8 h and 10 h tidal waterlogging time each day by simulated devices.There were five replicates for each treatment.The five tidal trays were used for each waterlogging treatment.The tidal trays were set on the bench and tidal inundation was simulated by submersible pumps operated by auto-electronic time clocks.The auto-electronic time clocks were set based on the tide table occurring at Xinyang Harbor in Jiangsu Province.The tidal regimes were fully adjustable by means of the time clocks.Free praline content,soluble sugar content,chlorophyll a,chlorophyll b,chlorophyll c,chlorophyll a/ chlorophyll b,leaf photo synthetic rate and total biomass were measured for plants in every treatment.The results showed that soluble sugar content,leaf photo synthetic rate and total biomass tended to increase with the increasing waterlogging time,then decrease in the experiment.These values of 6 h waterlogging time reached the maximal,which were significant higher than those of other treatments.Free praline content increased with longer waterlogging time from 4 h waterlongging treatment;the free praline content of 10 h waterlogging time was largest among all treatments and that of 4 h waterlogging time was lowest,which was significantly lower than those of other treatments.There were significant differences among treatments in chlorophyll b and chlorophyll c content except chlorophyll a and chlorophyll a/b.The chlorophyll b content of 4 h waterlogging time and chlorophyll c content of 10 h waterlogging time were lowest among all treatments,which were significantly lower than those of other treatments.The results indicated that S.anglica grew best in 6 h waterlogging time every day condition.For S.alterniflora has accelerated new land formation by expanding through sediment accretion,which resulted in the niche of S.anglica moving back and only high tide could reach the niche.Thus the change in hypsography and less waterlogging duration would explain the decline of S.anglica to some extent.更多还原