不同潮汐和盐度下红树植物幼苗秋茄的化学计量特征

借助室内潮汐模拟系统,分析秋茄幼苗的叶片、茎,根在不同淹浸时间梯度和盐度梯度下N、P、K、Ca、Cl、Mg、Al、Fe、Zn、Cu、B等元素的化学计量特征变化.结果表明水文因子能够显著影响秋茄不同器官的化学计量特征;幼苗的元素化学计量在盐度和淹浸两类水文因子下表现出不同的响应特征:特别是N、K、Ca、Cl、Mg、Na、Zn,Cu元素含量在不同程度的水文胁迫下存在明显的差异;盐度组内,幼苗对Na,Cl的选择性吸收随盐度增高而增强,同时对K、Ca,Mg的吸收减弱;随盐度的增大,盐分(Na、Cl、K、Ca、Mg)在不同器官中的含量表现出趋同效应;淹浸组N:P比为3-11,盐度组N:P比为6-15,明显小于同类研究.综合分析认为秋茄幼苗受到N元素限制,而P元素始终未成为限制因子,随水文胁迫的加强,N限制也加大,且盐度胁迫比淹浸胁迫表现的更明显.通过化学计量学和水文学的分析,为摸清中国红树林保护和恢复的主要红树植物秋茄的适生环境提供科学依据.     

Seasonal changes in element contents in mangrove element retranslocation during leaf senescene

The concentrations of nitrogen (N), phosphorus (P), potassium (K), sodium (Na), calcium (Ca), magnesium (Mg) and chlorine (Cl) were followed monthly in pre-senescence leaves and post-abscission leaves of Kandelia candel (L.) Druce at the Jiulongjiang estuary, and Fujian, China. The element retranslocation efficiency (RE) was studied during leaf senescence. The element RE's evaluated using different methods were compared and a new method was put forward to evaluate element RE during leaf senescence in evergreen trees without concentrated leaf fall. The results showed that during leaf senescence, 77.22% N, 57.53% P, and 44.51% K were translocated out of senescing leaves. Translocation of nutrients out of senescing leaves back into shoots was an important nutnent-conservation mechanism for N and P, was less important for K, and did not occur for Ca, Mg, Na, or Cl. One of the reasons for the high primary productivity of mangroves in nutrient poor sites (especially with low N) is the high nutrient use efficiency.     

红树植物秋茄分子生物学研究进展

秋茄Kandelia obovata Sheue,LiuYong是分布于热带、亚热带海岸带与河口潮间带的常绿红树植物,在海岸生态系统中具有重要的功能和价值。文中综述了近年来国内外关于秋茄分子生物学方面的研究进展,主要包括基于分子标记的秋茄亲缘地理关系与遗传多样性研究,基于双向电泳技术的蛋白质组学研究,以及逆境胁迫响应基因的克隆与功能验证研究;最后还结合当前研究现状展望了秋茄分子生物学未来研究工作的方向。     

Variation in the δ<Superscript>13</Superscript>C of Two Mangrove Plants is Correlated with Stomatal Response to Salinity

To better understand the relationship between salinity and the carbon stable isotope composition (expressed as δ¹³C) of mangrove plants and to test whether the patterns of variation in δ¹³C of mangrove plants differ from those of nonhalophytes as response to salinity, the effect of salinity on leaf δ¹³C in two dominant mangrove species, Aegiceras corniculatum and Kandelia candel, was studied. Furthermore, to determine whether the variation in δ¹³C of mangrove species is adjusted by stomatal conductance, K. candel was selected as an example, and leaf gas-exchange characteristics of the seedlings were measured. It was observed that both mangrove species had a lower leaf δ¹³C under their optimum salinity (1.50% for Ae. corniculatum and 2.00% for K. candel). This variation in δ¹³C of mangrove plants was attributable largely to stomatal adjustment as for nonhalophytes in which a strong correlation between δ¹³C and relevant photosynthetic properties is observed. This result suggests that the different response pattern in δ¹³C was a consequence of the variation in stomata in relation to the different tolerance to salinity. The optimum salinity inferred by leaf δ¹³C provides a feasible method for comparing salt tolerance between mangrove plants belonging to different species, which is useful for mangrove restoration.     

Forest structure of a subtropical mangrove along a river inferred from potential tree height and biomass

The hypothesis was tested that potential tree height and biomass in mangroves decrease downstream with the tidal gradient along the Okukubi River in Okinawa Island, Japan. The mangrove stands consisted of Bruguiera gymnorrhiza (L.) Lamk. and Kandelia obovata (S., L.) Yong (Rhizophoraceae). Four sites were selected considering the distance from the mouth of the river. Soil salinity increased downstream, while soil total nitrogen content decreased. The soil redox potential did not vary along the river. Maximum gross photosynthesis and tree height for each species decreased downstream. The potential tree height (H_max) inferred from the stem diameter (D_0.1)–tree height (H) relationship ( a, h, coefficient) in each species decreased downstream. The tree density (ρ)–mean tree size () relationships ( K, α, coefficient) determined for four sites revealed that the mean tree size at any given tree density decreased downstream, which indicates the decrease of potential biomass. Furthermore, an index for biomass () was homogeneous within a site regardless of tree density, i.e. the value of α at each site did not differ significantly from 1.0 (p > 0.05). The decreases in potential tree height and biomass may be partially ascribed to the stressful environments at the downstream sites characterized by high salinity (>2.6%) and nitrogen-poor soils (<0.25 ppt) in our study area.     

中国东南沿海15个秋茄种群遗传多样性的SRAP分析

为进一步保护和恢复红树林资源提供分子方面的基础资料和科学依据,本研究采用SRAP标记对15个中国东南沿海红树植物秋茄种群的亲缘关系进行了分析.从120对参试引物组合中选出46对重复性好、条带清晰的引物组合对供试的15份材料基因组DNA进行PCR扩增,得到大小在50～1 000 bp之间条带270,其中多态性条带107条,多态性位点率为39.63%.15个秋茄种群的遗传相似系数在0.004～0.845之间,平均为0.412,说明中国东南沿海秋茄种群存在较丰富的遗传多样性.聚类分析把15份供试种群材料划分为4个类群.15个秋茄种群的遗传多样性没有明显的地域性差异,同一样地域的不同种群之间具有遗传上的差别.建议在今后我国的红树林保护中,应加强对海南东寨港、深圳福田、湛江东北大堤和湛江附城的秋茄种群保护.     

人工红树林中黑口滨螺和黑线蜒螺分布的差异性

研究了福建九龙江河口不同林龄、不同红树种类的人工林中黑口滨螺（Littoraia elanostoma）和黑线蜒螺（Nerita lineata）的分布情况.结果表明,黑线蜒螺主要分布于秋茄林内,且其生物量随林龄增加而增加;桐花树林内黑口滨螺的生物量和密度均大于林龄相近的秋茄林,但个体大小则小于秋茄林.黑口滨螺的生物量在桐花树林内随林龄增加呈现先增加后减少的趋势,而在秋茄林内则随林龄增加而减少.这种差异性反映了人工红树林植物种类及其演替过程对腹足类动物分布的影响.     

三种红树植物叶片的比较解剖学研究

研究了采自福建九龙江口的3种红树植物,秋茄(Kandeliacandel)、木榄(Bruguieragymnorrhiza)和红海榄(Rhizophorastylosa)的叶片结构并探讨了其生态学意义。结果表明,这3种红树植物叶片都具有适应海生环境的结构,较厚的角质层,表皮之内有内皮层,内皮层属贮水组织;气孔都分布在下表皮,下陷,并有大的孔下室;中脉有发达的维管束,其导管粗大。从叶片的横切面来看,秋茄叶片具有对称的结构,为等面叶;木榄和红海榄的叶片结构不对称,为异面叶。3种植物叶内都含有较丰富的单宁,以秋茄最高,红海榄次之,木榄最少。这些结构差异可为物种鉴定提供依据。     

盐度对秋茄凋落叶分解过程中物质与能量动态的影响

在室内人工模拟潮汐, 研究了4种盐度(0、10‰、25‰和35‰, 分别代表淡水、低盐、中盐和高盐)下秋茄(Kandelia candel)凋落叶分解过程中物质与能量动态的差异。结果表明, 高盐处理下的失重率和平均分解速率显著低于淡水和低盐处理, 而高盐下的半分解理论值则高于其他处理; 盐度对分解过程中的残叶氮磷变化动态有显著影响, 其中, 残叶氮的释放速率在实验后期会随着盐度的升高而上升, 高盐度下残叶总氮含量显著低于低盐或淡水处理; 而在分解第1周, 淡水或低盐处理能加速磷的释放, 但中高盐度残叶中总磷含量最终会低于淡水和低盐处理; 盐度同样能对残叶热值产生显著影响, 淡水和低盐处理下的碎屑热值要显著高于高盐处理下的残叶热值, 但不同盐度下分解的能量损失差异不显著。     

Accumulation and Dynamics of Cu,Pb, Zn and Mn Elements in Kandelia candel (L.) Druce Mangrove Community of Jiulong River Estuary of Fujian

The accumulation and biocycle of Cu, Pb, Zn and Mn elements were studied in Kandelia candel (L.) Druce mangrove community of Jiulong River Estuary of Fujian. The pool amounts of Cu, Pb, Zn and Mn elements in the forest soil (0～30 cm in depth) were 6.86, 4.23, 25.64 and 134. 67 g · m-2, respectively. The respective element contents ranged from in different parts of the plant, 1.85～6.97, 0.37～3.74, 16.0～25.2 and 140～1405 μg· g-1 of Cu, Pb, Zn and Mn. The pool amounts of elements in standing crop of the community were 87.98, 40. 34, 335.34 and 8006.99 mg · m-2 for Cu, Pb, Zn and Mn respectively. The pool amounts of Cu, Pb, Zn and Mn elements in residues were: 593.06, 49.27, 2450.79 and 43486.70 μg · m-2 respectively. The biocycle of the elements in the community were described as follows: Annual uptake of Cu was 10. 17, Pb 4.32, Zn 49. 14 and Mn 2268. 16 mg · m-2; Annual return of Cu was 2.21, Pb 0.70, Zn 18.63 and Mn 1574.98 mg· m-2; Annual retention of Cu was 7.96, Pb 3.62, Zn 30. 51 and Mn 693.18 mg · m-2. The turnover periods of Cu, Pb, Zn and Mn were 40, 58, 18 and 5 year, respectively. The absorption, utilatizion and cycle coefficients were in the order of Mn〉Zn〉Cu〉Pb.