光照条件对蒙古栎幼苗生长及形态特征的影响

对生长于不同光照环境(林内和林外)下的蒙古栎幼苗的形态特征进行了比较.结果表明,光照条件对蒙古栎幼苗的生物量及其分配具有明显影响,林外幼苗单株生物量为林外的4.48倍,其中以根系生物量的差别为最大,林外为林内的6.23倍;林外与林内幼苗根冠比分别为2.70和1.11.在不同的光照条件下,蒙古栎幼苗的叶片形态表现出明显不同,林外叶片比叶面积明显低于林内,分别为139.55cm2/g 和284.94cm2/g,林内约为林外的2.04倍;一次生长叶面积林外明显低于林内,总叶面积则高于林内.二次生长使蒙古栎幼苗的叶面积有明显增加,但是经过二次生长后,幼苗的单株生物量没有明显增加,说明二次生长叶片对于蒙古栎幼苗生物量的积累没有明显贡献;光照对于蒙古栎主干及根系的形态具有明显影响,林外幼苗高(包括二次生长)明显低于林内幼苗,而地径则相反,林外幼苗根系的长度和直径则明显高于林内幼苗;林外幼苗顶芽体积明显大于林内幼苗.同时,林外幼苗的二次生长导致顶芽体积明显下降,从而对翌年的高生长量和未来干型产生影响.认为,蒙古栎幼苗通过形态上的一系列可塑性变化来适应不同的光环境以获取最大的碳收益.     

福建漳江口红树林区秋茄幼苗生长动态

通过福建漳江口红树林自然保护区内8个样方24个小样方人工种植600个秋茄胚轴,在3a时间内对秋茄胚轴建立、幼苗生长以及环境因子进行定期观测。研究结果表明：林缘空地的秋茄生长状况良好,白骨壤林内最不利于秋茄幼苗的生长。潮位、盐度、底质土壤理化因子不是造成该样地各样方间秋茄幼苗生长差异的主要原因。动物取食、光照状况以及种间竞争是限制秋茄生长的主要环境因子。秋茄胚轴在长根前易于随潮水漂走,底质土壤中自骨壤致密的根系抑制了秋茄胚轴的定植,导致白骨壤林内秋茄幼苗漂走的数量最多。昆虫和螃蟹等动物的取食是导致林内已经固着生长的秋茄幼苗大量死亡的最主要原因,而林外被取食的幼苗个体极少。此后秋茄幼苗能否继续成长,主要取决于幼苗所接受到的光照条件。3a后,在荫蔽的树冠下,秋茄幼苗无法存活;而在林外,秋茄幼苗已经长成幼树。在林外滩涂上迅速生长的互花米草,也将影响秋茄幼苗的更新和生长。     

秋茄(Kandelia candel)幼苗对多氯联苯污染的生理生态响应

通过盆栽实验,研究了4种不同浓度（180、900、1800和2700μg kg^-1）的多氯联苯（PCBs）对红树植物秋茄幼苗的茎高、茎径、生物量、相对生长速率以及叶片的叶绿素含量、水势、丙二醛含量和游离脯氨酸含量等生理生态指标的影响,结果表明：（1）在所设PCBs浓度范围内,PCBs对秋茄幼苗的茎高、茎径、生物量和相对生长速率等生长指标的生长没有产生不利的影响,相反具有促进作用,红树植物秋茄在PCBs污染情况下能旺盛生长;（2）在所设PCBs浓度范围内,秋茄幼苗叶片能保持相对正常的叶绿素水平和相对稳定的叶绿素a／b值,叶绿素a、叶绿素b和叶绿素a＋b的含量虽然有所降低,但均为对照的70％以上;叶绿素a／b值有所升高,但均未超过对照的15％。（3）随着PCBs浓度的升高,秋茄幼苗叶片水势呈上升趋势,而游离脯氨酸含量和膜质过氧化产物MDA含量均有一定的增加,说明PCBs对秋茄幼苗产生了一定的影响。总体来看,秋茄幼苗能在所设浓度的PCBs范围内正常生长,对PCBs有较强的耐受性和适应性,对PCBs污染的沉积物进行修复是可行的。     

秋茄(Kandelia candel)幼苗对多氯联苯污染的生理生态响应

通过盆栽实验,研究了4种不同浓度(180 、900 、1800 和2700μg kg^-1)的多氯联苯（PCBs）对红树植物秋茄幼苗的茎高、茎径、生物量、相对生长速率以及叶片的叶绿素含量、水势、丙二醛含量和游离脯氨酸含量等生理生态指标的影响,结果表明:（1）在所设PCBs浓度范围内,PCBs对秋茄幼苗的茎高、茎径、生物量和相对生长速率等生长指标的生长没有产生不利的影响,相反具有促进作用,红树植物秋茄在PCBs污染情况下能旺盛生长;（2）在所设PCBs浓度范围内,秋茄幼苗叶片能保持相对正常的叶绿素水平和相对稳定的叶绿素a/b值,叶绿素a、叶绿素b和叶绿素a+b的含量虽然有所降低,但均为对照的70%以上;叶绿素a/b值有所升高,但均未超过对照的15％。（3）随着PCBs浓度的升高,秋茄幼苗叶片水势呈上升趋势,而游离脯氨酸含量和膜质过氧化产物MDA含量均有一定的增加,说明PCBs对秋茄幼苗产生了一定的影响。总体来看,秋茄幼苗能在所设浓度的PCBs范围内正常生长,对PCBs有较强的耐受性和适应性,对PCBs污染的沉积物进行修复是可行的。     

淹水胁迫对秋茄(Kandelia candel)幼苗叶片C、N及单宁含量的影响——一个关于碳素-营养平衡假说的实验

通过在福建厦门同安湾潮间带滩涂种植红树植物秋茄,测定不同滩面高程（黄海高程1．6,1．0,0．4m）下1年生秋茄幼苗叶片单宁、C、N、叶绿素含量及幼苗的生长指标,研究了淹水胁迫对秋茄幼苗次生代谢物质单宁的影响及作用机理。结果表明,随着滩面高程的降低,淹水胁迫增强,秋加幼茁生物量、叶片C／N及单宁含量显著降低,在滩面高程0．4m处,与1．0m和1．6m相比,幼苗生物量分别降低了18．2％和47．0％,叶片C／N比值分别降低了17．5％和20．0％,相应地,叶片单宁含量也分别降低了44．6％和70．5％。秋茄幼苗叶片单宁含量与叶片C／N比值呈显著止相关（R=0．8425）,表明秋茄幼苗叶片中C、N含量及单宁含量对淹水胁迫的响应符合碳素／营养平衡假说。     

模拟微重力条件对植物幼苗生长的影响

与正常重力下生长的植物幼苗对照相比,在竖直平面内径回转器连续做１２０ｈ圆周回转的草莓和香石竹幼苗的生长状况发生如下变化：（１）株高和叶片数有所增加;（２）草莓的叶绿素含量降低４７．５％,香石竹叶绿素含量增加４．３％;（３）回转后两种幼苗的叶绿素的主要吸收峰位不变,而每个峰位吸收强度有所增加;（４）两思苗的叶片快速荧光动力学参数,回转后除ＣＡ／Ｆ０外,Ｆｖ／Ｆｏ、Ｆｖ／Ｆｍ和Ｔ１／２均有提高;（５）     

镉对小麦幼苗脂质过氧化和保护酶活性的影响

小麦幼苗经镉胁迫后,随着镉浓度的增高,叶征和根系中的膜脂过氧化产物丙二醛（ＭＤＡ）的含量和过氧物酶（ＰＯＤ）活性明显升高,超氧物歧化酶（ＳＯＤ）活性也有所提高。叶片中ＭＤＡ积累量和ＳＯＤ活性都高于根,而ＰＯＤ活性则是根高于叶片。随幼苗生长时间延长,叶片和根中的ＭＤＡ积累量增加,而ＳＯＤ活性却降低。     

作物细胞耐旱保护酶系统对外磁场的反应

作物细胞的耐旱保护酶由过氧化物酶（ＰＯＤ） 、过氧化氢酶（ＣＡＴ） 和超氧化物歧化酶（ＳＯＤ） 组成。对小麦种子施加０．１Ｔ 的磁场处理使其萌发时细胞中ＰＯＤ 活性提高,幼苗根系和叶片细胞中的ＰＯＤ 活性也发生了变化,叶片的ＰＯＤ 同工酶谱中多出了两个酶带。使用蛋白质合成抑制剂和转录抑制剂发现,ＰＯＤ 活性提高的原因是磁场处理促进了ＰＯＤ 合成的翻译过程。干旱胁迫下,经磁场处理的幼苗叶片细胞中的ＰＯＤ、ＣＡＴ 和ＳＯＤ 活性均比对照高,膜脂过氧化产物丙二醛（ ＭＤＡ） 含量比对照低,表明保护酶系统的功能有所增强。     

提高CO2浓度对两种亚热带树苗光合作用的影响

鼎湖山季风常绿阔叶林的主要优势乔木树种裂壳锥（Ｃａｓｔａｎｏｐｓｉｓｆｉｓｓａ （Ｃｈａｍ ｐ．ｅｘ Ｂｅｎｔｈ．） Ｒｅｈｄ．ｅｔＷｉｌｓ．）和荷木（Ｓｃｈｉｍ ａ ｓｕｐｅｒｂａ Ｇａｒｄｎ．ｅｔＣｈａｍ ｐ．）幼苗,盆栽于自然条件（ＣＯ２ 浓度３５０ μＬ·Ｌ－ １）或高ＣＯ２ 浓度为５００ μＬ·Ｌ－ １和空气ＣＯ２（３５０ μＬ·Ｌ－ １）的半开顶式气罩中。在生长最旺盛的６～９ 月份,高浓度ＣＯ２ 条件下生长的叶片,其光合速率比在自然条件下生长的提高７９％ ～９５％ 。当叶片在３５０ μＬ·Ｌ－ １和５００ μＬ·Ｌ－ １的ＣＯ２ 浓度下测定时,其光合速率无明显差异。高浓度ＣＯ２ 下生长的叶片其光合速率－ＣＯ２ 浓度响应曲线比对照（３５０ μＬ·Ｌ－ １）高,叶绿素和类胡萝卜素含量低,但叶绿素ａ 和ｂ 的比值及类胡萝卜素和叶绿素的比值不变。高浓度ＣＯ２ 下生长的叶片气孔导度明显降低。两种植物在８５ ｄ 的高浓度ＣＯ２ 的生长过程中,并未出现光合速率下调现象     

铝对玉米生长和硝酸还原酶活性的影响

测定了生长在Ａｌ２（ＳＯ４）３１００μｍｏｌ／Ｌ氮素营养液中的两个玉米品种（ＳＣ７０４和ＶＡ３５的根系和叶片）的ＮＡＤＨ－硝酸还原酶（ＥＣ１．６．６．１）和ＮＡＤ（Ｐ）Ｈ－硝酸还原酶（ＥＣ１．６．６．２）活性。     

Acclimation of a dominant mangrove plant (<Emphasis Type="Italic">Kandelia candel</Emphasis>) to soil texture and its response to canopy shade

Kandelia candel, a dominant plant species in Hong Kong mangroves, had different growth strategies during its seedling stage for acclimation to various soil types. Leaves of the seedlings grown in sandy soils (coarse texture) were significantly thicker than those in loamy–sandy and silty soils (fine texture). However, leaf weight per unit leaf area of seedlings grown in sandy soils was similar to that in loamy-sandy soils and was 1.60 times that in silty soils. These indicate that K. candel in sandy soils had developed a more loose leaf structure and a xerophilous characteristic during its seedling stage for acclimation to the features of coarse textured soils, which were low water holding capacity and low mineral content. In addition, for young seedlings grown in sandy and loamy–sandy soils, more biomass was allocated to roots than in silty soils, indicating that K. candel seedlings in sandy soils developed stronger roots for anchorage and water absorption; another xerophilous characteristic to acclimate to loose and coarse textured soils. As the plants became more mature, no significant difference in leaf thickness of the saplings was found between loamy-sandy and sandy soils. In order to acclimate to the low water holding capacity in sandy soils, K. candel seedlings had lower physiological activities including lower chlorophyll content; lower activities of root oxidase, nitrate reductase, peroxidase and superoxide dismutase but higher malonaldehyde contents than those in silty soils. Canopy shade is an important factor affecting the growth and physiology of K. candel. The seedling grew worse under the mangrove canopy than that in the open gap, with smaller leaf area, specific leaf area, leaf number and biomass. The seedlings under the canopy eventually died and no saplings were found under canopy shade, implying K. candel is a shade intolerant species and canopy shade might force its newly recruited individuals to expand out of the forest.     

The growth of Kandelia candel seedlings in mangrove habitats of the Zhangjiang estuary in Fujian, China

Propagules of Kandelia candel collected from the Zhangjiang estuary were planted in mangrove habitats along the intertidal gradient. The rooting rates of K. candel propagules varied spatially. The lowest rate occurred in Avicennia marina forest (69.7%). The rates were higher in K. candel forest (90.0%), at the fringe of the mangrove forest (89.3%) and on the bare tidal flat outside the mangrove forest (82.7%). After one year, the survival rates of seedlings planted under A. marina forest, K. candel forest, at the fringe of the mangrove forest, and on the bare tidal flat were 13.7%, 54.7%, 76.0%, and 34.7%, respectively. Among the surviving K. candel seedlings, those at the fringe of the mangrove forest and on the bare tidal flat had greater height, stem diameter, leaf number, leaf area, and biomass than those under A. marina and K. candel forests. These results demonstrated that establishment and growth of K. candel seedlings occurred successfully at the fringe of the mangrove forest, but were the worst under A. marina forest. The performance of K. candel seedlings was independent of physico-chemical characters of sediment. However, interspecies competition, propagule predation by insects and crabs, and the incident light had significant effects on seedling survival and growth.     

木榄和秋茄对水渍的生长与生理反应的比较研究

研究了不同水渍时间对两种红树植物木榄(Bruguiera gymnorrhiza(L.)Lam)和秋茄(Kandelia candel(L.)Druce)的生长与生理的影响.随着淹水时     

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。     

The Herbivore Assemblage, Herbivory and Leaf Chemistry of the Mangrove Kandelia obovata in Two Contrasting Forests in Hong Kong

The herbivore assemblage, intensity of herbivory and factors determining herbivory levels on the mangrove Kandelia obovata (previously K. candel, Rhizophoraceae) were studied over a 13-month period at two forests with contrasting growing conditions in Hong Kong. Mai Po was part of an eutrophic embayment in the Pearl River estuary and generally offered more favourable conditions for mangrove growth, whereas Ting Kok had a rocky substratum and oceanic salinity. Twenty-four insect herbivore species were recorded on K. obovata, with lepidopteran larvae that consume leaf lamina being the dominant species. While leaf litter production was similar at the two forests, herbivory level at Mai Po (mean = 3.9% in terms of leaf area loss) was more severe than that at Ting Kok (mean = 2.3%). Peak herbivory levels were found in summer at both locations (6.5% for Mai Po and 3.8% for Ting Kok). Young leaves of K. obovata at both locations were generally preferred by the herbivores from the period of late spring to summer. Concentrations of most feeding deterrents (ash, crude fibre, and total soluble tannins) were significantly higher in both young and mature leaves at Ting Kok, whereas leaf nutrients (total nitrogen and water) were the same at the two sites. Young leaves at Ting Kok contained about 30% more tannins than their counterparts at Mai Po. Significant differences in leaf chemistry also existed between young and mature leaves at either site. The differences were concomitant with the observed patterns of leaf herbivory on K. obovata, and suggest a potential relationship between environmental quality and plant defence against herbivory.     

The growth of Kandelia candel seedlings in mangrove habitats of the Zhangjiang estuary in Fujian, China

Propagules of Kandelia candel collected from the Zhangjiang estuary were planted in mangrove habitats along the intertidal gradient. The rooting rates of K. candel propagules varied spatially. The lowest rate occurred in Avicennia marina forest (69.7%). The rates were higher in K. candel forest (90.0%), at the fringe of the mangrove forest (89.3%) and on the bare tidal flat outside the mangrove forest (82.7%). After one year, the survival rates of seedlings planted under A. marina forest, K. candel forest, at the fringe of the mangrove forest, and on the bare tidal flat were 13.7%, 54.7%, 76.0%, and 34.7%, respectively. Among the surviving K. candel seedlings, those at the fringe of the mangrove forest and on the bare tidal flat had greater height, stem diameter, leaf number, leaf area, and biomass than those under A. marina and K. candel forests. These results demonstrated that establishment and growth of K. candel seedlings occurred successfully at the fringe of the mangrove forest, but were the worst under A. marina forest. The performance of K. candel seedlings was independent of physico-chemical characters of sediment. However, interspecies competition, propagule predation by insects and crabs, and the incident light had significant effects on seedling survival and growth.     

岷江冷杉林林窗小气候及其对不同龄级岷江冷杉幼苗生长的影响

对川西亚高山原始岷江冷杉(Abies faxoniana)林林窗内和林冠下小气候及岷江冷杉幼苗生长和生物量进行了两个生长季的连续观测。结果表明:6月林窗内与林冠下太阳辐射的日积累量没有显著性差异,而7~8月的日积累量则有显著性差异。整个生长季节,林窗内太阳辐射的平均积累量为8.10×MJ·m^-2,而林冠下太阳辐射的平均积累量为5.02×MJ·m^-2,两个位点太阳辐射积累量的显著差异主要来自7~8月日积累量的不同;林窗内5和15 cm层土壤的日平均温度比林冠下相应深度分别高2.1和2.7℃,差异显著。林窗内和林冠下3~8年岷江冷杉幼苗高增长率分别为1.2±0.3 cm·a^-1和1.1±0.3 cm·a^-1,差异不显著;9~20年岷江冷杉幼苗高增长率分别为6.2±2.4 cm·a^-1和3.0±0.9 cm·a^-1,差异显著。林窗内岷江冷杉幼苗根、主茎和总生物量与林冠下幼苗根、主茎和总生物量没有显著差异。不同年龄的岷江冷杉幼苗叶和侧枝生物量积累对林窗微环境的响应不同。     

Mapping and characterization of mangrove plant communities in Hong Kong

Ecological surveys were carried out to investigate the distribution and characterization of remaining mangrove stands in Hong Kong. The field studies indicate that 43 mangrove stands, excluding Mai Po Nature Reserve, still remained along the coastline of Hong Kong despite tremendous reclamation and development which occurred in the past 40 years. Most mangrove stands were found in Deep Bay (western part)and Sai Kung District (eastern coasts). The total areas occupied by these mangrove stands were 178 ha,varying from a very small stand (with 1–2 mangrove shrubs) to fairly extensive mangroves in Deep Bay (> 10 ha). It appeared that mangrove stands located in Deep Bay area were larger than those in the eastern coasts. Twenty plant species were identified from these stands, with 13 being exclusive or associate mangrove species. The major constituent species were Kandelia candel, Aegiceras corniculatum, Excoecaria agallocha and Avicennia marina. Rare species such as Heritiera littoralis were only found in a few mangrove stands. Out of the 43remaining mangrove stands, 23 were more worthwhile for conservation and their plant community structures were further investigated by transect and quadrat analyses. The importance values (sum of relative abundance,frequency and dominance) show that K. candel was the most dominant species. Species richness and Simpson's indices together with tree height, tree density and canopy area fluctuated significantly between mangrove stands. These values were used to prioritize the conservation potential of the remaining mangrove stands in Hong Kong. This revised version was published online in August 2006 with corrections to the Cover Date.     

毛乌素沙地优势灌丛对两种松树幼苗的保育作用

选择毛乌素沙地优势灌丛柠条(Caragana intermedia)、紫穗槐(Amorpha fruticosa)和沙柳(Salix psammophila)作为保育植物,选择2年生油松(Pinus tabulaeformis)和樟子松(Pinus sylvestris)幼苗作为目标植物,将其分别种植在开阔地、柠条、紫穗槐和沙柳4种微生境下,连续3a监测油松和樟子松幼苗的存活和生长动态,从而确定毛乌素沙地优势灌丛是否对植物幼苗的定居有促进作用。结果表明:柠条、紫穗槐和沙柳冠层下光照强度、大气温度和土壤温度都显著低于开阔地,致使土壤湿度增高,油松幼苗总存活率均显著高于开阔地,而樟子松幼苗总存活率仅紫穗槐冠层下显著高于开阔地(P0.05)。紫穗槐冠层下油松和樟子松幼苗总存活率均最高(P0.05),外来种紫穗槐可选为保育植物。保育灌丛下松树幼苗的主枝生长良好,并未受到抑制,但第1年主枝生长长度最小。光照强度和土壤湿度是决定主枝生长长度的重要因素。保育灌丛高度和冠幅面积与油松和樟子松幼苗存活率呈显著正相关(P0.05)。固氮灌丛(紫穗槐和柠条)对松树幼苗存活有持续的促进作用,但柠条冠幅结构紧密,可能因为对光的竞争,减弱了促进作用。沙柳灌丛下松树幼苗的存活率较低。油松幼苗具有一定程度的耐阴性,樟子松幼苗喜光性强,保育灌丛下油松幼苗存活率显著高于樟子松幼苗(P0.05)。总的来说,保育灌丛对松树幼苗的定居有促进作用,保育植物技术可作为一种有效的恢复措施,应用在毛乌素沙地的植被恢复中来。但是,保育灌丛的选择要考虑是本土种或外来种,以及灌丛的高度、冠幅大小、冠幅结构和化学效应,恢复物种的选择要考虑其自身的生物学特性及其与保育植物的相互作用。