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绒毛白蜡1年生容器播种苗密度试验结果表明,苗木高、径生长量及大径级苗木株数随育苗密度的减小而增加。育苗密度与各径级苗木株数紧密相关,据此建立了预测模型,编制出密度控制表。 相似文献
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水曲柳(Fraxinus mandshurica Rupr.)是东北地区三大珍贵硬阔叶用材树种之一,也是东北地区的重要造林树种。研究了不同育苗密度对水曲柳床播苗木生长的影响,结果表明,当密度达到100株/m^2时,为最优育苗密度,其苗高、地径、主根长、侧根数、生物量最优,有利于优质壮苗的培育。 相似文献
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《林业科学》2021,57(3)
【目的】探究密度和行距配置对毛白杨苗木生长、养分含量和光截获的影响,筛选毛白杨苗木适宜的密度和行距配置,为提高毛白杨苗木质量、节约毛育苗成本提供参考。【方法】以毛白杨新品种"北林雄株1号"苗木为试验材料,采用双因素完全随机区组设计,设置高、中、低3种育苗密度[50 000(A_1)、41 667(A_2)和31 250(A_3)株·hm~(-2)]和3种行距配置[行状配置B_1(行距0.8 m)、带状配置B_2(2行1带,窄行距0.6 m+宽行距1.0 m)和带状配置B_3(2行1带,窄行距0.4 m+宽行距1.2 m],测定毛白杨苗木生长指标、养分含量、光截获和叶面积指数。【结果】1)密度和行距配置对毛白杨苗木生长指标影响显著(P0.05),中密度带状配置A_2B_3的苗高、根生物量和总生物量最大,分别为294.65 cm、151.92 g和328.77 g,较高密度行状配置A_1B_1分别提高30.21%、62.78%和26.96%;2)密度和行距配置显著影响毛白杨叶氮浓度,A_3B_3的叶氮浓度最大(16.43 g·kg~(-1));带状配置较行状配置可显著提升苗木茎根的氮浓度;3)密度和行距配置的交互作用对毛白杨苗木光截获影响不显著(P0.05),行距配置对毛白杨苗木光截获和叶面积指数影响极显著(P0.01),带状配置显著增加毛白杨苗木光截获和叶面积指数,带状配置B_3的光截获和叶面积指数最大,分别为0.87和3.59,显著高于行状配置B_1;4)不同密度和行距配置下,光截获显著影响毛白杨生长指标(P0.05),光截获与毛白杨苗高、地径、地上生物量、地下生物量和总生物量呈极显著正相关(P0.01),与茎根比呈显著负相关(P0.05),其中光截获与生物量的决定系数(R~2)最高,达0.408。【结论】在不同密度和行距配置下,光截获是影响苗木苗高、地径、地上生物量、地下生物量和总生物量的关键因素。密度和行距配置不同,苗木生长指标以及养分浓度均表现出相应变化。从苗木质量上考虑,中密度带状配置B_3毛白杨的生长指标、养分含量和光截获最佳,苗木质量最佳。从生产经济上考虑,高密度带状配置B_2、高密度带状配置B_3、中密度带状配置B_2、中密度行带状配置B_3的密度和行距配置模式均较佳。 相似文献
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<正> 科学研究和实践经验证明,使用移植苗或三、四年生播种苗营造的林分,遭受杂草灌木不良影响的程度比较小,所需抚育的次数也最少,并且在定植的头几年,生长速度就显著地超过一、二年生播种苗所营造的林分。由于这个缘故,近年来采用松树大苗造林,在林业上得到普遍地推广。这类苗木可由密集的大苗区供应,也可在密度较小的播种苗区,通过截断苗木根系的办法进行培育。 相似文献
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In order to identify the optimum cutting density for producing the highest number of plantable seedlings of poplar clones,
a split-plot randomized block design was used to establish four cutting densities in plots. Based on data on the survival,
leaf area, seedling height, caliper, and biomass of 1-year-old seedlings of clones Nanlin-95, Nanlin-895, Nanlin-1388 and
NL-80351, the growth characteristics and seedling quality under four cutting densities were analyzed. Results indicated that
the leaf area, stem and leaf biomass, and caliper of seedlings of all four poplar clones increased with the decrease in cutting
density. Leaf area index reached its highest level at the spacing of 40 cm×40 cm, while the aboveground biomass of the seedling
on an area basis increased as the cutting density increased. Seedling quality at low cutting density was higher than that
at closer cutting density. The quantity of first-grade seedlings (grade I) for clones Nanlin-95 and Nanlin-895 was achieved
at the spacing of 40 cm×50 cm; for NL-1388 and NL-80351, it was 50 cm×50 cm. According to the seedling quality and the number
of plantable seedlings produced, the suggested cutting density for these four poplar clones was 50,000 stems/hm2. 相似文献
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Shortleaf pine (Pinus echinata Mill.) seedlings in 24 open-top chambers were exposed to combinations of ozone (carbon-filtered (control), ambient, 1.7 x ambient, and 2.5 x ambient) and acidic precipitation (pH 5.3, 4.3 and 3.3) for 16 months (1989 harvest) or 28 months (1990 harvest). Although the effects of acid rain were generally not significant, there was a trend toward increased aboveground biomass and leaf area in seedlings subjected to the low pH treatments. Because N concentrations in the soils generally increased with decreasing pH, we concluded that the effects of acid rain on aboveground biomass and leaf area were a consequence of an increasing concentration of soil N. In the 1989 harvest, seedlings in the 2.5 x ambient ozone treatment had significantly less biomass in all aboveground plant components and significantly less total leaf area than seedlings in the 1.7 x ambient ozone treatment. In the 1990 harvest, there were no significant effects of ozone on total aboveground biomass, although there was a trend toward reduced biomass in seedlings in the 2.5 x ambient ozone treatment. Both total leaf area and leaf biomass were significantly less in seedlings exposed to 2.5 x ambient ozone for 28 months than in both control seedlings and seedlings in the 1.7 x ambient ozone treatment. The greater, but not always significant, aboveground biomass and leaf area of seedlings in the 1.7 x ambient ozone treatment compared with control seedlings may be associated with the observed increase in soil nitrate concentration as a result of increased rates of leaf senescence and litterfall. 相似文献
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Wood density, a gross measure of wood mass relative to wood volume, is important in our understanding of stem volume growth, carbon sequestration and leaf water supply. Disproportionate changes in the ratio of wood mass to volume may occur at the level of the whole stem or the individual cell. In general, there is a positive relationship between temperature and wood density of eucalypts, although this relationship has broken down in recent years with wood density decreasing as global temperatures have risen. To determine the anatomical causes of the effects of temperature on wood density, Eucalyptus grandis W. Hill ex Maiden seedlings were grown in controlled-environment cabinets at constant temperatures from 10 to 35 degrees C. The 20% increase in wood density of E. grandis seedlings grown at the higher temperatures was variously related to a 40% reduction in lumen area of xylem vessels, a 10% reduction in the lumen area of fiber cells and a 10% increase in fiber cell wall thickness. The changes in cell wall characteristics could be considered analogous to changes in carbon supply. Lumen area of fiber cells declined because of reduced fiber cell expansion and increased fiber cell wall thickening. Fiber cell wall thickness was positively related to canopy CO2 assimilation rate (Ac), which increased 26-fold because of a 24-fold increase in leaf area and a doubling in leaf CO2 assimilation rate from minima at 10 and 35 degrees C to maxima at 25 and 30 degrees C. Increased Ac increased seedling volume, biomass and wood density; but increased wood density was also related to a shift in partitioning of seedling biomass from roots to stems as temperature increased. 相似文献
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不同滩面高程和光照条件下白骨壤幼苗的早期生长差异 总被引：1，自引：0，他引：1
对厦门杏林曾营海岸低、中、高3个高程(分别为厦零3.35 m、3.74 m和4.15 m)滩面上红树人工幼林林内、林外自然生长的白骨壤2月龄幼苗的生长状况进行对比分析。结果表明:在林外,中高程滩面上的白骨壤幼苗单叶面积、基径、茎高、叶生物量、茎生物量和总生物量均最大;低高程滩面上叶片较厚,肉质化程度高,叶片数最多;3个高程的根生物量差异不显著。在林内,不同高程间幼苗生长差异主要体现在叶片和茎高,低、中高程之间差异不大,但比高高程的叶片厚,肉质化程度高,叶片数多。除茎高外,林外3个高程的其它指标都明显高于林内。光照对幼苗生长的影响大于高程的影响。综合分析结果表明,厦门海域白骨壤红树林生态恢复的适宜高程为厦零3.74 m(相当于本研究的中高程样地),且白骨壤为不耐阴植物,人工造林时,应为后代幼苗的自然更新预留空间。 相似文献
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《Scandinavian Journal of Forest Research》2012,27(4):322-328
Abstract Actual climate models for central Europe predict prolonged summer droughts. Knowledge on how the interaction between light and water availability affects regeneration will hence be of major importance. In an experiment carried out under controlled conditions, newly emerged beech seedlings were grown in pots with sand during 54 days. Three treatments applying three different light levels (2, 9 and 43% relative light intensity) were combined with two soil water treatments (control and drought). At the end of the experiment, seedlings were separated into leaves, stem and root and the seedlings’ dry mass, leaf area and stem length was determined. Low irradiance (2%) had a strong negative effect on dry weights of seedling components, leaf area and specific leaf mass. Drought clearly affected biomass partitioning for seedlings at high irradiance levels (43%). An interaction between irradiance and drought on biomass partitioning in beech seedlings was observed at medium irradiance level (9%). Within a wide range of light levels in the forests, both light and drought may affect biomass partitioning in young seedlings. 相似文献
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The adaptation responses to different water conditions and the drought tolerance of Sophora davidii seedlings were assessed in a greenhouse experiment. Two-month-old seedlings were subjected to the following water supplies
for 95 days: 100, 80, 60, 40 and 20% of field water capacity. The seedlings at 100% FC had the greatest productivity, height,
basal diameter, branch number, leaf number and leaf area. Water supply <80% FC was the threshold of drought-initiated negative
effects on seedling growth, yield and physiological processes; these parameters were severely reduced at 20% FC, however,
there was no plant death during the experiment. Moreover, water stress decreased leaf relative water content, specific leaf
area, leaf area ratio, and water-use efficiency (WUE), whereas it increased the biomass allocation to roots, which resulted
in a higher root:stem mass ratio under drought. The S. davidii seedlings tolerated drought by maintaining high leaf relative water content and by reducing branching and leaf expansion.
However, low productivity and WUE at 20% FC suggested that seedlings did not produce high biomass under severe drought. Therefore,
prior to introducing S. davidii in forestation efforts, a water supply >40% FC is recommended for seedlings to maintain growth and productivity. These results
provide insights into limitations and opportunities for establishment of S. davidii in arid regions. 相似文献
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不同光环境下喜树与四川大头茶幼苗的表型可塑性 总被引：2，自引：1，他引：1
研究不同光环境对常绿阔叶林中喜树和四川大头茶幼苗生长的影响.结果表明:1)落叶阔叶树种喜树幼苗通过提高自遮荫程度、增大叶悬挂角、增加根生物量比和减小比叶面积适应旷地环境,在旷地中具有最大的相对生长速率,而常绿阔叶树种四川大头茶幼苗没有表现出对旷地光环境的良好适应;2)四川大头茶幼苗在林窗中通过增加叶片数、提高单叶面积、比叶面积和叶生物量比接受更多光能,相对于旷地和林下具有较快的高度生长,喜树幼苗比四川大头茶幼苗在林窗中具有更大的单叶面积、叶柄长度、总叶面积和总叶面积增长率;3)在3-8月,喜树在林窗中的株高增加约35.3 cm,约为四川大头茶(约6.6 cm)的5.3倍,喜树在林窗中具有明显的光资源竞争优势,表现出比常绿阔叶树种四川大头茶更高的相对生长速率,这就是喜树存在于常绿阔叶林的一个重要原因;4)郁闭林下的光资源有限,2个树种幼苗都不能在林下良好生长;5)喜树幼苗叶性状在不同光环境的可塑性指数远大于四川大头茶,这是喜树能够在常绿阔叶林中存在的另一重要原因. 相似文献
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水分胁迫对白杨杂种无性系生理和生长的影响 总被引：7，自引：0，他引：7
为探索水分胁迫对白杨杂种无性系气体变换和生长的影响,以白杨双杂交杂种新无性系Ｂ４３０苗木为试验材料,在３种水分胁迫条件下,对各无性系生理和生长指标进行了分析。结果表明,在不同水分胁迫下,无性系苗木的Ｐｎ、Ｔｒ,Ｇｓ,Ｌａ,Ｃｉ等日变化模式基本一致,但受胁迫的苗木各生理过程受到明显抑制。各生长指标对水分胁迫的敏感性不同,苗高和单叶叶面积对水分胁迫最敏感,叶片数和生物量的敏感性较差,随着水分胁迫加强, 相似文献