模拟潮汐淹浸对红树植物老鼠簕种子萌发及幼苗生长的影响

在温室内用自动控制装置模拟正规半日潮淹浸作用对老鼠簕种子发芽与幼苗生长的影响,设淹水0、3、6、9、12、15、18、21和24h·d-1共9个淹水时间梯度,人工海水盐度为2%,测定不同淹水时间下老鼠簕种子萌发、幼苗株高、叶面积、生物量以及幼苗叶脯氨酸含量、丙二醛(MDA)含量、叶绿素含量和超氧化物歧化酶(SOD)活性等生理生化指标.结果表明,长时间淹水(≥15 h·d-1)会推迟老鼠簕种子萌发的时间,并使发芽率和成苗率降低,淹水＜15 h·d-1适宜老鼠簕种子的萌发.随着淹水时间的增长,脯氨酸含量、MDA含量和SOD活性均先下降后上升,叶绿素含量则逐渐降低.淹水≥3 h·d-1,幼苗生物量、单株叶面积、高生长和叶绿素含量与淹水时间均呈负相关.淹水0～3h·d-1,老鼠簕总叶绿素含量、根、茎、地上部分和总生物量积累均显著大于其他处理,淹水≥18 h·d-1,老鼠筋幼苗总生物量、叶面积、叶绿素含量显著降低,根冠比开始上升.在上述人工培养条件下,淹水0～3h·d-1是老鼠筋幼苗生长的最佳淹水时间,18h·d-1是老鼠簕幼苗生长的一个临界淹水时间,淹水≥18 h·d-1老鼠筋幼苗生长显著受到抑制.     

光照强度对8种红树植物幼苗生长和生物量分配的影响

选取无瓣海桑(Sonneratia apetala Buch-Ham.)、卤蕨(Acrostichum aureum Linn.)、桐花树(Aegiceras corniculatum Blanco.)、老鼠簕(Acanthus ilicifolius Linn.)、木榄(Bruguiera gymnorrhiza Lam.)、秋茄(Kandelia candel Druce.)、银叶树(Heritiera littoralis Ait.)和黄槿(Hibiscus tiliaceus L.)为研究对象,通过遮荫控制实验,研究这8种红树植物幼苗在不同光照强度(自然光强的100%、45%、30%、10%)下的生长和生物量分配特征。结果表明:(1)遮荫对无瓣海桑幼苗相对生长速率、生物量积累、基径的增长和叶片数的增长均有显著的抑制作用;(2)桐花和老鼠簕在遮荫处理下生长状况较好,遮荫对桐花生长的影响不显著,对老鼠簕幼苗的生长则有一定的促进作用;(3)当光照强度降低时,无瓣海桑、秋茄、老鼠簕、桐花树的幼苗都对地上部分投入了更多的生物量,其中秋茄、老鼠簕和桐花树通过提高叶生物量来获取更大的光能捕获能力。研究结果表明,从对光照的生长适应角度来看,桐花、老鼠簕和卤蕨适宜种植在郁闭度较高的林下;秋茄适宜在郁闭度较低的林下种植;真红树无瓣海桑和木榄以及半红树黄槿和银叶树则不适合在林下种植。     

喀斯特土壤上香樟幼苗接种不同AM真菌后的耐旱性效应

为探索喀斯特土壤适生植物香樟幼苗在接种不同AM真菌后的耐旱适应性,进行了香樟幼苗接种幼套球囊霉(Glomus etunicatum)和层状球囊霉(Glomus lamellosum)后水分胁迫处理试验。结果表明：（1）接种AM真菌显著提高了香樟幼苗的生物量积累,AM促进植株生物量效应依次为中度>轻度>正常>重度,同一水分胁迫处理下生物量幼套球囊霉>层状球囊霉。（2）中度干旱下香樟幼苗菌根依赖性最大,幼套球囊霉接种植株的菌根依赖性较层状球囊霉大。（3）接种AM真菌显著提高了植株叶片可溶性糖、可溶性蛋白质和脯氨酸含量,并降低了丙二醛含量;在正常供水下植株叶片可溶性糖、可溶性蛋白质和脯氨酸含量层状球囊霉接种>幼套球囊霉接种>对照,干旱胁迫下表现为幼套球囊霉接种>层状球囊霉接种>对照;干旱胁迫下的幼套球囊霉接种植株丙二醛含量低于层状球囊霉接种植株。（4）总体上,可溶性糖与脯氨酸相关性极显著,可溶性蛋白质与丙二醛之间呈显著负相关性。幼套球囊霉接种香樟幼苗的耐旱性高于和层状球囊霉接种香樟幼苗。     

低温胁迫下棉花幼苗对外源水杨酸的生理响应

以棉花幼苗为试材,通过叶面喷施不同浓度水杨酸的处理方法,研究外源水杨酸对低温胁迫下棉花幼苗的缓解效应。结果表明,0.6~0.8 mmol＆#183;L-1水杨酸预处理可以显著降低棉花幼苗叶片相对电导率（REC）和丙二醛（MDA）的积累量,从而缓解低温对质膜的过氧化伤害,并通过提高超氧化物歧化酶（SOD）、过氧化物酶（POD）、过氧化氢酶（CAT）的活性和可溶性糖、可溶性蛋白、脯氨酸等渗透调节物质的含量来适应低温环境。     

长期喷施ABA对云杉幼苗生长和生理特性的影响

采用单因素盆栽实验,通过叶面喷施5、10、15和20mg·L^-1 4个浓度的ABA溶液,研究了长期外源ABA处理对云杉（Piceaasperata）幼苗生长及生理特性的影响。5年的研究结果表明：长期不同浓度ABA处理显著影响了云杉幼苗的多种生长及生理生化指标。当ABA浓度为5、10和15mg·L^-1叫时有利于云杉幼苗根重、茎重和总生物量的积累,并且提高了叶片中可溶性蛋白和脯氨酸的含量,降低了MDA含量：20mg·L^-1 ABA处理使幼苗的叶重、总生物量、脯氨酸及可溶性糖含量显著下降,明显增加了叶片中MDA含量。此外,各浓度ABA处理均显著降低了云杉幼苗的株高、叶绿素含量以及SOD和APX活性。本研究结果显示,长期ABA处理对云杉幼苗生长和生理特性的影响与所喷施的ABA浓度有关,长期高浓度ABA（20mg·L^-1）处理不利于云杉幼苗生长。     

高温胁迫下2，4-表油菜素内酯对甜瓜幼苗生理及光合特性的影响

研究了高温胁迫下不同浓度2,4-表油菜素内酯（EBR）处理对甜瓜幼苗生长、叶片抗氧化酶活性和光合作用的影响。结果显示0．5～1．5mg·L-1 EBR处理能有效缓解甜瓜幼苗高温胁迫下受到的伤害,显著促进了幼苗生长,提高了叶片抗氧化酶活性、脯氨酸和可溶性蛋白含量、净光合速率（Pn）和气孔导度（G5）;降低了丙二醛（MDA）含量,胞间CO2浓度（Ci）和蒸腾速率（Tr）。研究结果表明,EBR缓解甜瓜幼苗高温胁迫具有剂量效应,以1．0mg·L-1 EBR的效果较好,有利于甜瓜幼苗在高温胁迫下抗氧化酶活性的维持和对光能的捕获与转换,促进生长。     

水分胁迫对白刺幼苗生物量和渗透调节物质积累的影响

以PEG-6000模拟不同程度的水分胁迫对白刺幼苗进行处理,研究了其植株干重及其K 、Na 、丙二醛、游离脯氨酸、可溶性糖的含量变化.结果表明,15%PEG胁迫下白刺幼苗的生物量最高,丙二醛含量最低,且二者与对照的差异均显著;随着水分胁迫程度的增强,K 含量逐渐降低并与对照差异显著,Na 含量先减少后增加而其总积累量无显著变化;游离脯氨酸和可溶性糖含量随着水分胁迫程度的增强而显著增加.因此,轻度水分胁迫有利于白刺幼苗的生长,有机溶质游离脯氨酸和可溶性糖是白刺适应干旱环境的主要渗透调节物质.     

格木幼苗对硝普钠-酸铝互作的生理响应

以格木（Erythrophleum fordii Oliv.）幼苗为材料,采用双因素完全随机设计实验方法,测定不同处理幼苗的光合色素和可溶性糖等生理指标,研究格木幼苗对硝普钠（SNP）-氯化铝（AlCl₃）互作的生理响应。结果显示,格木幼苗叶片中叶绿素a、叶绿素b和类胡萝卜素含量均在处理4（0.2 mmol/L AlCl₃、0.1 mmol/L SNP）时最高,在处理9（0.8 mmol/L AlCl₃、0 mmol/L SNP）时含量最低,而叶片中丙二醛（MDA）、游离脯氨酸含量则相反;叶片可溶性糖、可溶性蛋白含量在处理4时最高,在处理9时最低;处理10（0.8 mmol/L AlCl₃、0.1 mmol/L SNP）的超氧化物歧化酶（SOD）、过氧化物酶（POD）和过氧化氢酶（CAT）活性最高。施加SNP后,格木幼苗叶片中的叶绿素a、叶绿素b、类胡萝卜素、可溶性糖、可溶性蛋白含量及SOD、POD、CAT活性均显著高于未施加SNP处理。相关性分析表明,叶绿素a、类胡萝卜素、总叶绿素和可溶性蛋白含量等指标间均呈极显著正相关（P < 0.01）。本研究结果得出,低浓度AlCl₃（0.2 mmol/L）胁迫可促进格木幼苗的生长,添加外源SNP对高浓度AlCl₃（0.8 mmol/L）胁迫格木幼苗产生的毒害具有一定的缓解作用,可在格木幼苗的培育及抗性研究中推广应用。     

硝普钠对缺铁和硝酸盐胁迫下番茄幼苗生长及生理特性的影响

采用营养液培养方法,研究外源NO供体(硝普钠,SNP)对缺铁和硝酸盐胁迫番茄幼苗生长、养分吸收及抗氧化酶活性的影响.结果表明: 处理7 d后,缺铁使番茄幼苗生长受到抑制,叶绿素a、b、类萝卜素含量显著降低,出现明显失绿症状;降低叶片中超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)的活性,电解质渗漏率、丙二醛含量明显增加,脯氨酸和可溶性糖含量变化不显著,幼苗叶片和根中N、P、K、Ca、Mg、Fe含量比对照处理有不同程度的减少.硝酸盐和缺铁双重胁迫对番茄幼苗生长抑制加剧,叶绿素a、b、类萝卜素含量、SOD、POD和CAT活性显著降低,电解质渗漏率、脯氨酸、可溶性糖和丙二醛含量明显增加;番茄幼苗叶片和根中N、P、Mg、Fe含量显著减少,而K、Ca含量显著增加. 与不添加处理相比,添加0.1 mmol·L^-1 SNP处理使胁迫番茄幼苗的生长抑制明显缓解.添加0.1 mmol·L^-1 SF(亚铁氰化钠)的处理在SOD、POD和CAT等指标上也表现出一定程度的缓解或促进作用,但其他生理指标没有表现出缓解或促进作用,原因是SF中也含有铁离子.     

大气增温对杉木幼树叶片及细根生理特征的影响

为揭示亚热带森林对未来全球变暖的生理响应特征,本研究以杉木为研究对象,利用开顶式增温方式模拟气候变暖,研究其对叶片和细根丙二醛含量、活性氧代谢、渗透调节物质含量以及抗氧化酶活性的影响。研究结果显示：（1）增温显著增加杉木叶片和细根的丙二醛含量,且叶片丙二醛含量显著高于细根,说明增温加剧了杉木叶片和细根氧化损伤,且叶片氧化损伤程度高于细根;（2）增温后,杉木叶片脯氨酸和可溶性蛋白含量降低,细根脯氨酸和可溶性蛋白含量则增加;（3）增温显著提高了杉木叶片过氧化物酶活性,对杉木细根抗氧化酶活性无显著影响;（4）增温后,杉木叶片和细根活性氧含量未发生显著变化,杉木叶片活性氧含量显著高于细根。综合分析表明,尽管增温增加了杉木叶片和细根的氧化损伤,但杉木可以通过提高抗氧化保护酶活性（叶片）和积累较多的渗透调节物质（细根）来维持体内活性氧代谢平衡。可见,杉木地上和地下部分器官间的相互合作与协调使杉木能有效地适应高温环境。     

<Emphasis Type="Italic">Daphnia galeata</Emphasis> in the deep hypolimnion: spatial differentiation of a “typical epilimnetic” species

One of the most serious threats to tropical mangrove ecosystems caused by shrimp farming activities is the poor management of pond waste materials. We hypothesise that mangroves can tolerate chemical residues discharged from shrimp farms and can be used as biofilters, but the capability of mangroves to cope with solid sediments dredged from shrimp ponds is limited. Our study in Pak Phanang, Thailand, confirmed that the excess sediments discharged from nearby shrimp ponds reduced mangrove growth rates and increased mortality rates. A series of transformed multi-temporal satellite images was used in combination with the field data to support this claim. In addition, a comparison between four dominant mangrove species revealed that Avicennia marina could tolerate sedimentation rates of >6 cm year⁻¹, while Bruguiera cylindrica tolerated sedimentation rates of 5 cm year⁻¹ (total sediment depth = 25 cm) before dying, while Excoecaria agallocha and Lumnitzera racemosa performed intermediate. This outcome implied that in our situation A. marina and to lesser extent E. agallocha and L. racemosa could be more effective as biofilters than B. cylindrica, as they may survive the sedimentation longer in the disposal areas. Further studies on the impact of sedimentation and chemical pollution of shrimp farm wastes on mangrove mortality and growth are required.     

Mangroves as filters of shrimp pond effluent: predictions and biogeochemical research needs

Preliminary estimates of the ratio of mangrove forest: shrimp pond area necessary to remove nutrients from shrimp pond effluent are made using budgets of nitrogen and phosphorus output for semi-intensive and intensive shrimp ponds combined with estimates of total net primary production in Rhizophora-dominated mangrove forests in tropical coastal areas. If effluent is delivered directly to mangrove forest plots, it is estimated that, depending on shrimp pond management, between 2 and 22 hectares of forest are required to filter the nitrogen and phosphorus loads from effluent produced by a 1 hectare pond. While such ratios may apply to small scale, integrated shrimp aquaculture — mangrove forestry farming systems, the variability in mangrove hydrodynamics makes it difficult to apply such ratios at a regional scale. Before mangroves can be used to strip shrimp pond effluent more research is required on the effects that high ammonia and particulate organic matter loads in pond effluent have on nutrient transformations in mangrove sediments and on forest growth.     

Physical processes in the Rufiji delta and their possible implications on the mangrove ecosystem

The physical processes such as coastal currents, estuarine circulation and monsoon winds prevailing in the Rufiji delta are discussed. The relationship between these processes and the occurrence of long-term trapping of the river discharge and the outflow of waters from the mangrove swamps into the nearshore zone has been observed. The trapped waters in the nearshore zone significantly reduce the mixing between the estuarine and offshore waters, leading to the two waters having distinctive properties. The existence of the trapped waters in the nearshore zone is supported by evidence from a satellite image and aerial photograph and measurements of salinity and suspended sediment concentration. The trapping phenomenon is discussed in the light of its possible implications on the ecology of mangrove ecosystems. Trapping may explain the enhanced growth of the mangrove in the delta compared to other areas. This trapping effect may be providing more time for nutrient retention in the mangrove zone, incorporation of the decomposed leaf litter and fine sediments in the substrate, and settling of fruits and seedlings in the swamps, thereby enhancing the regeneration of the mangrove.     

Dissolved iron elution from mangrove ecosystem associated with polyphenols and a herbivorous snail

Interest in the systems supplying dissolved forms of iron to the sea from upland forests and wetlands has increased because iron is abundant on land but has low bioavailability in seawater. This can be a limiting factor for the growth of marine phytoplankton. Organic complex iron, a typical form of iron dissolved in seawater, is supplied to the ocean through rivers from forest and wetland soils. As a related study, we focus on mangrove ecosystems located at the boundary between the land and sea and on polyphenols present in leaves as ligands for the formation of iron complexes. When mangrove leaf litterfalls on the wet forest floor, phenolic compounds leach out from the leaves and might solubilize insoluble iron in the sediments (i.e., iron complexation). However, the reaction mechanism is not simple in the field, and it might be made more complex by tidal currents and intervention by crabs and snails, which consume mangrove leaf litter. In the present study, we focused on a detritivorous snail, Terebralia palustris, as a facilitator of iron solubilization associated with phenolic compounds, and examined how the snail contribute to iron solubilization processes. Our results indicated that the amounts of phenolic compounds in mangrove sediments are strongly related to iron solubilization. Furthermore, the average dissolved iron and phenolic contents in sediments from areas inhabited by the snail were significantly higher than those of sediments where the snail was not present. We additionally report that the solubilization of iron was promoted when snail feces were added to mangrove sediments. In conclusion, we propose that iron solubilization in mangrove sediments is promoted by the interaction between i) iron in the sediment, ii) phenolic compounds derived from mangroves, and iii) the consumption of leaves and the deposition of feces by the snail.     

Shrimp ponds lead to massive loss of soil carbon and greenhouse gas emissions in northeastern Brazilian mangroves

Mangroves of the semiarid Caatinga region of northeastern Brazil are being rapidly converted to shrimp pond aquaculture. To determine ecosystem carbon stocks and potential greenhouse gas emissions from this widespread land use, we measured carbon stocks of eight mangrove forests and three shrimp ponds in the Acaraú and Jaguaribe watersheds in Ceará state, Brazil. The shrimp ponds were paired with adjacent intact mangroves to ascertain carbon losses and potential emissions from land conversion. The mean total ecosystem carbon stock of mangroves in this semiarid tropical landscape was 413 ± 94 Mg C/ha. There were highly significant differences in the ecosystem carbon stocks between the two sampled estuaries suggesting caution when extrapolating carbon stock across different estuaries even in the same landscape. Conversion of mangroves to shrimp ponds resulted in losses of 58%–82% of the ecosystem carbon stocks. The mean potential emissions arising from mangrove conversion to shrimp ponds was 1,390 Mg CO₂e/ha. Carbon losses were largely from soils which accounted for 81% of the total emission. Losses from soils >100 cm in depth accounted for 33% of the total ecosystem carbon loss. Soil carbon losses from shrimp pond conversion are equivalent to about 182 years of soil carbon accumulation. Losses from mangrove conversion are about 10‐fold greater than emissions from conversion of upland tropical dry forest in the Brazilian Caatinga underscoring the potential value for their inclusion in climate change mitigation activities.     

Mangrove growth in New Zealand estuaries: the role of nutrient enrichment at sites with contrasting rates of sedimentation

Mangrove forest coverage is increasing in the estuaries of the North Island of New Zealand, causing changes in estuarine ecosystem structure and function. Sedimentation and associated nutrient enrichment have been proposed to be factors leading to increases in mangrove cover, but the relative importance of each of these factors is unknown. We conducted a fertilization study in estuaries with different sedimentation histories in order to determine the role of nutrient enrichment in stimulating mangrove growth and forest development. We expected that if mangroves were nutrient-limited, nutrient enrichment would lead to increases in mangrove growth and forest structure and that nutrient enrichment of trees in our site with low sedimentation would give rise to trees and sediments that converged in terms of functional characteristics on control sites in our high sedimentation site. The effects of fertilizing with nitrogen (N) varied among sites and across the intertidal zone, with enhancements in growth, photosynthetic carbon gain, N resorption prior to leaf senescence and the leaf area index of canopies being significantly greater at the high sedimentation sites than at the low sedimentation sites, and in landward dwarf trees compared to seaward fringing trees. Sediment respiration (CO₂ efflux) was higher at the high sedimentation site than at the low one sedimentation site, but it was not significantly affected by fertilization, suggesting that the high sedimentation site supported greater bacterial mineralization of sediment carbon. Nutrient enrichment of the coastal zone has a role in facilitating the expansion of mangroves in estuaries of the North Island of New Zealand, but this effect is secondary to that of sedimentation, which increases habitat area and stimulates growth. In estuaries with high sediment loads, enrichment with N will cause greater mangrove growth and further changes in ecosystem function.     

1960-2010年广西红树林空间分布演变机制

为全面摸清1960—2010年广西红树林空间分布及其演变机制,采用多源遥感数据提取不同年度的红树林空间分布信息,分析了广西红树林空间分布动态特点,采用基于斑块的红树林空间演变机理分析方法,研究了1960/1976—2010年广西红树林空间演变机制。结果表明:1960/1976年、1990s年、2001年、2007年和2010年广西红树林斑块数量分别为1020、829、1094、1718个和1712个,面积分别为9062.5、7430.1、7015.4、6743.2、7054.3 hm2,近50年间红树林面积减少了22.16%,年均减少0.53%,斑块数量增加了67.8%;斑块平均面积由1960/1976年的8.9 hm2减小至2010年的4.1 hm2,大斑块数量显著减少,斑块破碎化严重;不同时期、不同区域和海湾,红树林面积和斑块数量的变化量、变化速率均不同;1960/1976年的斑块中,只有24个斑块至2010年时尚保持稳定,占2.4%,绝大部分斑块都发生了某种程度的变化。进一步分析结果表明:1960/1976—2010年,斑块消失(46.1%)、碎化(40.4%)、萎缩(13.5%)是面积减少的主要途径,新增(70.0%)和碎化(29.9%)是斑块数量增加的主要途径,但在不同时期,斑块数量和面积在各个途径上发生的变化量不尽相同;养殖塘和盐田建设(80.0%)、工程建设(10.9%)和围垦(9.1%)是面积净减少的驱动因子,自然过程(92.6%)和人工造林(7.4%)是斑块数量净增加的驱动因子,不同驱动因子在不同时期对斑块数量和面积变化的影响程度不同;斑块数量变化主要由自然过程作用下通过新增(39.6%)、消失(-9.1%)两个途径,以及养殖塘和盐田作用下通过消失(-15.3%)、碎化(14.5%)两个途径发生,斑块面积变化主要由自然过程影响下通过新增(17.5%)、扩张(12.6%)、消失(-6.1%),以及养殖塘和盐田建设驱动下通过斑块消失(-14.8%)、碎化(-13.9%)、萎缩(-6.6%)3个途径发生。     

Mariculture development in Kenya: alternatives to siting ponds in the mangrove ecosystem

Pond culture of brackishwater prawns and shrimps has recently generated much interest in Kenya. The mangrove areas are the target zones for the construction of these ponds. With the increasing awareness of the unique ecological role played by the mangroves, there is an urgent need to stop the conversion of mangrove swamps into aquaculture ponds. To develop pond aquaculture without destroying the mangroves, a shift from tide-fed to pump-fed pond systems is recommended in order to divert the farming from the mangroves to higher grounds. Mangrove-friendly mariculture practices like pen, cage and raft culture are discussed. Methods of efficiently utilising the already destroyed mangrove areas are considered.     

挖捕泥丁对红树植物白骨壤幼苗生长影响的模拟

沿海群众为了增加收入挖掘林下滩涂海洋经济动物可口革囊星虫,这是导致中国红树林退化的一个重要原因.本文研究了挖掘深度、弧度和频率3个因素对1年生白骨壤幼苗的苗高、基径、单叶面积、比叶面积、生物量和死根干质量等生长指标的影响,了解挖掘活动对红树林生长的影响机理,并筛选出红树林健康状况的评估指标.结果表明:挖掘活动使白骨壤幼苗的苗高和基径增长量、单叶面积、比叶面积和生物量显著减少,而死根干质量显著增加;挖掘深度和弧度对幼苗生长具有明显影响,但频率的影响不显著;当挖掘深度＜5 cm、弧度＜240°、每月2次以下时,对幼苗的伤害较轻,而挖掘深度＞5 cm则会对幼苗造成严重影响.