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1.
设置不同光强梯度(透光率分别为100%、40%、20%、10%和5%,光照强度PPFD分别为201.3、77.0、37.5、19.2、9.8 μmol·m-2·s-1),研究光对杉木种子萌发和幼苗早期生长的影响,分析杉木种子萌发、幼苗存活、生长、形态响应、生物量积累及其分配格局对不同光环境的响应策略.结果表明: 杉木种子的萌发率、存活率、建植率和萌发指数在不同光强梯度下均有显著差异,且40%的透光率是种子最适萌发条件,萌发率最高,而全光照下存活率和建植率最高;随光照强度的减弱,杉木幼苗茎长增大,根长、子叶长、子叶厚、真叶数呈降低趋势,而基径在各光照强度间无显著差异;总生物量、根生物量、茎生物量、叶生物量均表现为全光照下最大.随着光照强度的减弱,光合组织与非光合组织生物量比、叶生物量比呈降低趋势,茎生物量比呈增加趋势,根冠比和根生物量比无显著差异.弱光环境促进杉木种子萌发,不利于杉木幼苗存活和生长.在弱光环境下,杉木幼苗通过增大茎生物量来提高对弱光环境的耐受力.  相似文献   

2.
何彦龙  王满堂  杜国桢 《生态学报》2007,27(8):3091-3098
以高寒草甸克隆植物黄帚橐吾为实验材料,通过遮荫网模拟植被遮荫,研究种子大小与萌发及幼苗生长能力的关系和幼苗对光照条件的反应。结果表明:(1)在自然光照下,黄帚橐吾种子大小对种子萌发的影响显著,大种子的萌发率高于小种子。遮荫生境下,大、小种子萌发率有所降低,但遮荫对小种子萌发的影响比大种子显著。小种子的萌发率下降了近1/8,而大种子的萌发率仅下降了1/11。(2)黄帚橐吾种子大小对幼苗生物量积累影响显著,大种子幼苗总生物量(TB)大于小种子幼苗的。但生物量的分配与播种时间相关,播种后60 d,在自然光照条件下,大种子幼苗对根生物量的分配大于小种子幼苗,而对叶生物量的分配则正好相反。在遮荫环境中,大、小种子幼苗普遍对根的生物量分配增加,大种子幼苗根冠比(R/S)大于小种子幼苗。(3)黄帚橐吾种子大小对幼苗的生长也有明显影响。在自然光照下,小种子幼苗的相对生长速率(RGR)较大于大种子幼苗,但叶面积比率(LAR)、叶面积干质量比(SLA)、叶干质量(LWR)差别不明显。在遮荫条件下,幼苗的LAR、SLA、LWR显著增加,但大、小种子幼苗间差异不显著,幼苗的RGR减小,小种子幼苗的减小趋势大于大种子幼苗。  相似文献   

3.
何彦龙  王满堂  杜国祯 《生态学报》2007,27(8):3091-3098
以高寒草甸克隆植物黄帚橐吾为实验材料,通过遮荫网模拟植被遮荫,研究种子大小与萌发及幼苗生长能力的关系和幼苗对光照条件的反应。结果表明:(1)在自然光照下,黄帚橐吾种子大小对种子萌发的影响显著,大种子的萌发率高于小种子。遮荫生境下,大、小种子萌发率有所降低,但遮荫对小种子萌发的影响比大种子显著。小种子的萌发率下降了近1/8,而大种子的萌发率仅下降了1/11。(2)黄帚橐吾种子大小对幼苗生物量积累影响显著,大种子幼苗总生物量(TB)大于小种子幼苗的。但生物量的分配与播种时间相关,播种后60d,在自然光照条件下,大种子幼苗对根生物量的分配大于小种子幼苗,而对叶生物量的分配则正好相反。在遮荫环境中,大、小种子幼苗普遍对根的生物量分配增加,大种子幼苗根冠比(R/S)大于小种子幼苗。(3)黄帚橐吾种子大小对幼苗的生长也有明显影响。在自然光照下,小种子幼苗的相对生长速率(RGR)较大于大种子幼苗,但叶面积比率(LAR)、叶面积干质量比(SLA)、叶干质量(LWR)差别不明显。在遮荫条件下,幼苗的LAR、SLA、LWR显著增加,但大、小种子幼苗间差异不显著,幼苗的RGR减小,小种子幼苗的减小趋势大于大种子幼苗。  相似文献   

4.
选择毛乌素沙地优势灌木中间锦鸡儿为研究对象,人为控制4种降水量水平来测定中间锦鸡儿幼苗的形态,。生物量干重,气体交换和叶绿素荧光参数,结果表明,不同施水量显著影响幼苗株高,基径,叶数,叶面积,生物量干重,净光合速率,蒸腾速率,气孔导度以及水分利用效率,157.5mm和630mm施水的幼苗以上参数显著低于472.5mm施水的幼苗,157.5mm和630mm施水量的幼苗PSIII光化学效率和最大荧光与初始荧光比显著小于472.5mm施水量的幼苗;不同施水量对幼苗生物量干重分配有显著影响;随着施水量增加,根冠生物量干重比显著减少。  相似文献   

5.
不同水分条件对毛乌素沙地油蒿幼苗生长和形态的影响   总被引:13,自引:1,他引:12  
肖春旺  周广胜  赵景柱 《生态学报》2001,21(12):2136-2140
选择毛乌素沙地优势半灌木油蒿为研究对象,人为控制4种施水量水平来观察油蒿幼苗的生长和形态对全球降水量变化的响应。结果表明,不同施水量显著影响了幼苗生物量及其分配,枝叶形态和细根分布。随着施水量的增加,幼苗生物量、株高、总枝数和长度、总叶片数、总叶面积、比叶面积和细根长逐渐增大,而生物量根冠比、硬叶特征和叶肉质化程度逐渐减小。  相似文献   

6.
该文在玻璃温室内的遮阴环境下,采用盆播方法研究了辽东栎种子特征(大小和种皮)和播种深度(0、3、6、10 cm)对种子萌发和幼苗生长的影响。结果表明:(1)辽东栎大种子萌发率、萌发速率、萌发值和萌发指数在所有播种深度均高于小种子。其中非去皮种子萌发率、萌发速率和萌发指数在0 cm播种深度的不同大小种子间差异显著,去皮种子所有萌发参数在6和10 cm播种深度的不同大小种子间均差异显著;去皮可促进大种子萌发,但抑制小种子萌发;不同大小种子所有萌发参数均在0 cm播种深度最大,在10cm播种深度最小。(2)不论有无种皮,大种子萌发幼苗的叶片数、单株叶面积、总干物质质量和根冠比在所有播种深度均大于小种子萌发幼苗;去皮种子萌发幼苗的株高、基径、叶片数、单株叶面积和总干物质质量在所有播种深度均不同程度地小于非去皮种子萌发幼苗,但前者根冠比在0、3、6 cm播种深度大于后者;随着播种深度增大,幼苗株高、叶片数、单株叶面积、总干物质质量和根冠比等生长参数均呈减小趋势,但基径随播种深度增大而增大。  相似文献   

7.
研究气候变暖导致的温度升高和降水格局的变化对典型植被类型建群种植物种子萌发和幼苗存活的影响,对于预测森林群落的发展趋势、种质资源保育及森林抚育更新具有重要意义.以寒温带针阔混交林的建群种和优势种红松Pinus koraiensis、蒙古栎Quercus mongolica种子和幼苗为研究对象,采用空间替代法模拟温度升高和降水变化,观察其种子萌发和幼苗生长情况.结果表明:与种源地相比,蒙古栎种子在温度升高与降水增加(年均温+4.9℃,+330 mm)或降水减少(年均温+2.8℃,-249 mm)的条件下萌发率分别下降了13%和18%,但差异不显著.红松种子在温度升高与降水增加的情况下萌发率比种源地提高了2.29倍,而降水减少时则下降了64%,不同的地点对红松的萌发率差异极显著;不同的温度、降水组合对红松和蒙古栎幼苗的生长均产生不同影响,在温度升高与降水增加与降水减少的情况下,1年生蒙古栎幼苗的株高、基径和主根长度均有明显下降,与种源地差异显著,而对红松幼苗生长的影响差异不显著;温度升高和降水增加或降水减少的交互作用使蒙古栎幼苗和红松幼苗总生物量下降,尤其是在温度升高与降水增加的条件下两种幼苗的生物量最小,分别比种源地下降了62%和20%.但统计分析表明,红松幼苗生物量在3个样地间没有显著差异.温度升高和降水变化均降低了两种幼苗的根冠比,而比叶面积没有显著差异.  相似文献   

8.
为了探讨珍稀树种对短期氮素添加的响应,该文研究了氮素添加(0、0.1、0.2、0.4和0.6g·kg~(-1)土)对观光木、棱角山矾和半枫荷幼苗生长和生物量分配的影响。结果表明:3个树种幼苗对外源氮素添加的反应不同,施氮显著促进观光木幼苗株高、基径、冠幅以及全株生物量和各部分生物量的增加,中低氮促进半枫荷幼苗的生长,但高氮抑制其生长;少量施氮对棱角山矾幼苗的形态和生物量参数没有产生显著影响,中量施氮抑制其生长。氮素营养的改变显著影响3种植物幼苗的生物量分配,观光木幼苗的根生物量比和根冠比均随施氮量的增加而显著降低;除高氮处理外,半枫荷幼苗的根生物量比和根冠比均随供氮量的增加而显著升高;棱角山矾的根生物量比和根冠比均随供氮量的增加而显著升高,可能与施氮抑制其茎叶的生长有关。总的来看,观光木幼苗更能耐受高氮条件,半枫荷幼苗次之,而棱角山矾幼苗不耐高氮;但到当年生长季末,各氮处理半枫荷幼苗的株高、基径和总相对生长速率均显著大于其它两种植物。  相似文献   

9.
目的:开展干旱胁迫对紫茎泽兰种子萌发的影响研究,为其入侵机制的揭示和田间防治提供借鉴。方法:采用聚乙二醇(PEG-6000)梯度溶液模拟干旱胁迫环境,研究紫茎泽兰(Ageratina adenophora)种子萌发和幼苗生长对干旱胁迫的响应。结果:随着PEG-6000浓度的增加,紫茎泽兰种子的发芽率、发芽势、发芽指数和幼苗根长、根冠比均呈先升后降的趋势,而种子活力指数、幼苗胚根长度、胚轴长度、株高相对增长速率和叶片光合色素含量均呈持续下降趋势。结论:轻度干旱胁迫有利于紫茎泽兰种子萌发,而中度和重度干旱胁迫均不利于紫茎泽兰幼苗生长。紫茎泽兰在种子萌发阶段对干旱具有一定的抗逆性。  相似文献   

10.
气候变化将增加地表平均气温、改变降水格局, 会影响到种子出苗和幼苗生长, 进而影响物种的更新动态。为探讨增温和降水变化对东灵山地区建群树种辽东栎(Quercus mongolica)种子出苗和一年生幼苗生长和适应状况的影响, 该文利用环境控制生长箱开展了温度和降水量的双因素控制实验, 温度设置3个梯度: 月平均气温(对照)、增温2 ℃和增温6 ℃; 降水量设置3个梯度: 月平均降水量(对照)、减水30%和加水30%。结果表明: 1)辽东栎的种子出苗率和一年生幼苗的生长对增温和降水变化的响应不一致, 种子出苗率主要受到降水及其与温度交互作用的影响, 幼苗生长仅受到温度和降水独立作用的影响; 2)春季增温2 ℃或降水量增加均使辽东栎种子出苗期提前; 增温6 ℃与降水量减少的水热组合延迟了种子出苗期并使其存活率和出苗率显著降低, 但在此温度下增加降水量则增加了出苗速率和出苗率。3)增温2 ℃对其生长无显著影响, 增温6 ℃则在不同水分条件下显著地增加了幼苗的比叶面积、抑制了叶的伸长生长, 同时也显著降低了各器官生物量积累, 并减少了幼苗生物量向根的分配; 降水量减少降低了幼苗根生物量, 但未影响总生物量和根冠比, 降水量增加显著促进了幼苗地上部分的生长, 特别是叶的生长。因此, 适当地增温或增加降水量将增加辽东栎幼苗的更新潜力, 但增温和降水量减少导致的干旱化将显著降低幼苗的更新潜力。  相似文献   

11.
Rainfall and soil moisture variability have a strong effect on plant survival and seed germination in arid environments, yet very little is known about the effects on roots and growth of woody seedlings. Here we focused on the effects of variability in both amount and frequency of water supply on juvenile root and leaf functional traits and growth of seven Mediterranean shrub species occurring in arid SE Spain, Anthyllis cytisoides, Atriplex halimus, Ephedra fragilis, Genista umbellata, Lycium intricatum, Retama sphaerocarpa, and Salsola oppositifolia. In a 14-month greenhouse experiment we manipulated water supply expecting that reduced water amount and pulses of watering of different magnitude affected functional traits and seedling growth, even if the amount of water provided was the same. Different watering patterns altered soil drying dynamics, with reduced supply of water amount and frequent watering becoming the driest treatment. We found that roots of all species responded to alterations in water supply by changing biomass allocation patterns (i.e., higher root-to-shoot mass [R:S] ratio in droughted plants), and by altering fine roots diameter, measured in terms of specific root length. Indeed, differences in growth rate among species were significantly linked to fine roots diameter and biomass allocation, which relates to uptake capacity of roots. However, relative growth rate and leaf traits such as specific leaf area were insensitive, likely because prolonged droughts over longer periods of time seem necessary to constraint growth in all these arid shrubs.  相似文献   

12.
南亚热带森林24种乔木的种子萌发和幼苗生长   总被引:7,自引:0,他引:7  
以膨胀珍珠岩为基质,在光和暗的条件下,对24种南亚热带森林乔木的种子萌发和幼苗生长进行了研究。种子的形态和重量与种的演替阶段有关,种子的重量也与不同的种有关。不同种的萌发率差异较大,种子较大的种,萌发率较高。肉质果实的种子,开始萌发的时间较长。光和暗条件对萌发率和萌发速度无明显影响。幼苗高度和种子重量呈正相关,这一相关在光条件下比暗条件下更明显。暗条件明显地引起群落演替早期的树种的茎徒长,限制根的生长,而对演替后期种无显著的影响。幼苗地上部分和根系生物量的分配与种的演替阶段有关,也与不同的科有关。幼苗地上部分和根系生物量的分配也受光暗条件的影响,而不受种子重量的影响。根和叶的生物量分配和种在其群落演替阶段有关。幼苗的生物量与种子重量有显著的正相关。幼苗的相对生长率相差较大,在没有营养供应的生长基质中,以演替中间阶段的种的相对生长率较大。幼苗从种子的物质利用效率与种子重量呈负相关,而与种的演替阶段无明显的相关。  相似文献   

13.
为探讨全球变化温度升高对外来入侵植物薇甘菊(Mikania micrantha)化感作用和入侵能力的影响,研究不同温度(22、26和30℃)处理对其种子萌发、幼苗生长、生物量分配、挥发物成分和化感作用的影响。结果表明,薇甘菊种子在温度为22、26和30℃时的萌发率分别为29.2%、52.4%和75.2%。30℃条件下薇甘菊种子萌发率最高,萌发速度快。温度升高显著增加薇甘菊茎的生长、增加对茎的生物量分配。GC-MS和GC测定显示,温度升高改变了薇甘菊挥发物的化学成分。同时,生物测定表明,温度升高增强薇甘菊挥发物对萝卜(Raphanus sativus)和油菜(Brassica campestris)的化感作用。说明温度升高促进了薇甘菊种子的萌发和生长,同时增强了该植物的化感作用,温度升高可能加速薇甘菊的生物入侵。  相似文献   

14.
Improving natural regeneration of bamboos after they die following mass flowering is critical for conservation of giant pandas. However, little is known about factors that affect seed germination and seedling growth of bamboos. We studied seed germination and seedling growth in Fargesia qinlingensis, which mass flowered in a giant panda habitat in the Qinling Mountains of China in early 2000, in laboratory and greenhouse conditions. Seed germination rate was tested under light and dark conditions 5 and 12 months after seed collection. Germination rate displayed no significant difference under light or dark conditions 5 months after seed collection, but was significantly greater in the dark than under light 12 months after seed collection, suggesting light inhibition of seed germination. A 2×2 factorial design was conducted to test the effects of nitrogen (N fertilization and non-N fertilization) and light [full sun and shade (i.e., 14% full sun)] on seedling growth and biomass allocation. N fertilization significantly increased seedling growth, resulting in greater seedling height, more branches, more leaves, greater stem biomass, and greater leaf biomass. Seedlings under 14% full sun conditions had a significantly lower percentage of biomass allocated to the stem. The root/shoot ratio was significantly greater in non-N/shade than non-N/full sun, while there was no significant difference in this ratio between N/shade and N/full sun, suggesting that nitrogen fertilization compensated for the effect of shade on biomass allocation. Our results suggest that N fertilization could be employed in restoration of F. qinlingensis stands after die-off following mass flowering.  相似文献   

15.
Root:shoot (R:S) biomass partitioning is one of the keys to the plants' ability to compensate for limiting resources in the environment and thus to survive and succeed in competition. In adult plants, it can vary in response to many factors, such as nutrient availability in the soil or reserves in the roots from the previous season. The question remains whether, at the interspecific level, reserves in seeds can affect seedlings' R:S ratio in a similar way. Proper allocation to resource‐acquiring organs is enormously important for seedlings and is likely to determine their survival and further success. Therefore, we investigated the effect of seed mass on seedling R:S biomass partitioning and its interaction with nutrient supply in the substrate. We measured seedling biomass partitioning under two different nutrient treatments after 2, 4, 6, and 12 weeks for seventeen species differing in seed mass and covering. We used phylogenetically informed analysis to determine the independent influence of seed mass on seedling biomass partitioning. We found consistently lower R:S ratios in seedlings with higher seed mass. Expectedly, R:S was also lower with higher substrate nutrient supply, but substrate nutrient supply had a bigger effect on R:S ratio for species with higher seed mass. These findings point to the importance of seed reserves for the usage of soil resources. Generally, R:S ratio decreased over time and, similarly to the effect of substrate nutrients, R:S ratio decreased faster for large‐seeded species. We show that the seed mass determines the allocation patterns into new resource‐acquiring organs during seedling development. Large‐seeded species are more flexible in soil nutrient use. It is likely that faster development of shoots provides large‐seeded species with the key advantage in asymmetric above‐ground competition, and that this could constitute one of the selective factors for optimum seed mass.  相似文献   

16.
王俊  王卓晗  杨龙  任海 《应用生态学报》2008,19(10):2097-2102
黧蒴锥是华南用于人工造林和生态恢复的优良乡土树种.选取浇水频率和凋落物覆盖量两个控制因子,研究在不同的土壤湿度和凋落物覆盖量条件下,黧蒴锥种子萌发及幼苗存活和生长特征.结果表明: 凋落物对黧蒴锥种子萌发和幼苗生长的影响与环境的潮湿程度相关.当浇水频率为每天1次时,凋落物覆盖会抑制黧蒴锥种子萌发和幼苗早期生长,导致种子萌发率降低、幼苗死亡率提高; 在浇水频率为2 d 1次和3 d 1次时,凋落物覆盖可以改善土壤的水分状况,有助于种子萌发和幼苗存活.凋落物覆盖还可以显著地提高幼苗的生物量.在通过播种来实现亚热带灌木林地更新时,可利用凋落物覆盖促进黧蒴锥的种子萌发和幼苗存活.  相似文献   

17.
Artificial defoliation has been used commonly to simulate defoliation by insect herbivores in experiments, in spite of the fact that obvious differences exist between clipping foliage and natural defoliation due to insect feeding. We used a greenhouse experiment to compare the effects of artificial and western spruce budworm (Choristoneura occidentalis Freeman) defoliation on the growth and biomass allocation of 3-yr old half-sib seedlings from mature Douglas-fir [Pseudotsuga menziesii (Mirb.) Franco variety glauca] trees that showed phenotypic resistance versus susceptibility to budworm defoliation in the forest. Artificial clipping of buds mimicked the effects of budworm feeding on total seedling biomass when 50% of the terminal buds were damaged. However, artificial defoliation decreased seedling height, relative growth rate of height, and shoot: root ratio more than budworm defoliation, whereas budworm defoliation decreased stem diameter relative growth rate more than artificial defoliation. Half-sib seedling progeny from resistant maternal tree phenotypes had greater height, diameter, biomass, and shoot: root ratio than seedlings from susceptible phenotypes. We concluded that careful artificial defoliation could generally simulate effects of budworm defoliation on total biomass of Douglas-fir seedlings, but that the two defoliation types did not have equal effects on biomass allocation between shoot and root. Further, an inherently higher growth rate and a greater allocation of biomass to shoot versus root are associated with resistance of Douglas-fir trees to western spruce budworm defoliation.  相似文献   

18.
六盘山区辽东栎的实生苗更新及其影响因子   总被引:3,自引:2,他引:1       下载免费PDF全文
 研究了六盘山区辽东栎(Quercus liaotungensis)灌丛的种子产量、土壤种子库组成、湿沙和风干贮藏对种子寿命的影响以及动物取食子叶对种子萌发和幼苗建立的影响。结果表明, 辽东栎灌丛种子的完好率为27.51%, 被动物取食或搬运种子的比例(41.51%)显著高于其他类型种子(p < 0.01); 辽东栎次生林土壤种子库中萌发和虫蛀种子分别占35.16%和38.29%, 完好种子仅占13.65%, 捕食动物主要通过贮藏或搬运而影响土壤种子库中的种子密度。湿沙贮藏60天的辽东栎种子自动萌发率高达96.67%, 短期贮藏可加快种子的萌发进程, 提高萌发率和萌发指数, 但随着贮藏时间的延长, 种子萌发进程延迟, 萌发率、萌发指数和活力指数均不同程度地降低。排除动物取食处理的幼苗在林窗和林下生境的存活率分别为80%和83%, 而不排除动物取食幼苗在2种生境中分别仅有25%和31%能够存活, 表明子叶在幼苗建立中具有重要作用。林窗中幼苗子叶的动物取食率(85.00%)高于林下(71.00%), 子叶留存的幼苗在林窗中的存活率(6.00%)低于林下(15.50%), 而子叶被取食幼苗的存活率在两种环境中基本相等(分别为18.50%和18.00%)。  相似文献   

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