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441.
The ultrastructure of egg cells in Abies alba was examined to elucidate the lack of maternal inheritance of plastids. Before fertilization, maternal plastids are absent
in the perinuclar zone containing mainly mitochondria and smooth endoplasmic reticulum. During egg cell development the maternal
plastids are transformed into large inclusions which are situated mostly towards the periphery of the egg cell, and finally
disintegrate. As a consequence, they do not participate in zygote formation.
RFLP analysis of cpDNA of parental trees and their F1 interspecific hybrids (A. alba×A. numidica, A. alba×A. nordmanniana, A. nordmanniana×A. Alba) using HindIII and BamHI showed a paternal mode of cpDNA inheritance. Paternal inheritance has also been found with PCR/RFLP analysis of cpDNA from
parental trees and their hybrids (A. alba×A. pinsapo, A. pinsapo×A. alba, A. pinsapo×A. numidica) using ApaI and HaeIII digests, as well as in the crosses of A. cephalonica×A. nordmanniana, A. nordmanniana×A. cephalonica, A. cephalonica×A. numidica using TagI digests.
Received: 1 June 1998 / Accepted: 14 August 1998 相似文献
442.
443.
三峡库区世坪森林公园的常绿阔叶林处在中亚热带北部,群落中48.65%的物种具热带性质,35.14%的物种具温带性质;33.78%的物种集中在忍冬科(Caprifoliaceae)、壳斗科(Fagaceae)等7个科,全部38个科中81.58%的科仅有1~2种植物在群落中出现;群落含有具先锋意义的伴生种。这些都反映出该地带的次生常绿阔叶林的一般特点。栲树(Castanopsisfargesi)的重要值在乔木层和灌木层均居第一,特别是在乔木层该值显著高于其它种,说明此处的常绿阔叶林是以栲树为建群种的单优群落,而且栲树种群径级结构符合其正常发育规律,因而群落相对稳定。该群落对于中亚热带地带性植被的生态学和生物多样性的基础研究具有重要意义,对于退化生态系统的恢复和三峡水库的水源涵养具有典范作用。 相似文献
444.
川滇冷杉(AbiesforrestiiCC.Rogers)是冷杉属高大乔木。用水蒸汽蒸馏提取其叶精油,用气相色谱-质谱联用方法进行成分研究,结果表明,α-蒎烯、β-蒎烯和柠檬烯是构成川滇冷杉叶精油的主要化学成分。 相似文献
445.
Abstract. The forest structure in a large, relatively homogeneous area of pristine Picea abies taiga in the southern boreal region west of the Ural mountains was studied along four 500-m long transects. P. abies dominated the forest in association with Abies sibirica and Betula spp. The mean volume of living trees was 216 m3/ha. This value varied among the four transects, from 138 - 252 m3/ha. Mean density of trees (DBH > 1 cm) (and variation over the transects) was 2 064/ha (1670 - 2710). Living trees classified as dying or seriously damaged made up 2.9 (2.5 - 3.5) % of the living tree volume. Betula was an important canopy component and made up 16% of the living tree volume. The number of dead standing trees varied from 195 - 325/ha, corresponding to a volume of 10.8 - 70.7 m3/ha. The density of trees with a broken stem was 90 - 170/ha and their estimated volume 7.6 - 41.3 m3/ha. Standing dead trees and trees with broken stems represented 10.4 and 8.9% of the total standing tree volume (living + dead), respectively. The mean volume of decaying logs on the forest floor was 117 (84.4–156.2) m3/ha, corresponding to 54 (35 - 113) % of the living tree volume. The canopy-forming trees were present in the understory as abundant saplings and suppressed individuals. The size distribution of the dominant tree species resembled the inverse J-shape. Generally, the forest was characterized by a high small-scale structural variation and a larger-scale relative homogeneity. This pattern is consistent with forest dynamics where the forest consists of a small-scale mosaic of patches in different stages of recovery following disturbance. Our results suggest that the ecology and dynamics of extensive areas of natural boreal forests can be driven by small-scale disturbance. 相似文献
446.
We have adapted a procedure for the isolation of genomic DNA from needles of silver fir (Abies alba) to meet the requirements for large-scale analysis of the population genetics of forest trees. Our modifications permit the
entire procedure to be carried out in Eppendorf tubes, which greatly minimizes time, plant material, and the amounts of chemicals.
DNA is recovered with a mean efficiency of 80 μg/g needles, is suitable for restriction by the common endonucleases, and serves
as a substrate for PCR. 相似文献
447.
Abstract. Post-fire succession was reconstructed for a sector located in the southern part of the Québec boreal forest. Forest composition for different periods since fire was evaluated using a stand initiation map together with ecological maps representing both site conditions and stand types. Nine fires covering at least 100 ha and representing a chronosequence of more than 230 yr were used. Although a relatively clear successional pattern from deciduous to coniferous composition relating to time-since-fire was observed, Pinus banksiana stands showed an erratic distribution not related to succession but possibly to the pre-fire stand composition. A comparison with forest cover maps produced after a recent spruce budworm outbreak, showed that succession toward coniferous dominance appeared to be interrupted by spruce budworm (Choristoneura fumiferana) outbreaks which, by killing Abies balsamea, lead to a mixed deciduous forest composition. A simple empirical model based on a negative exponential distribution of age classes was developed to evaluate how changes in the fire cycle would affect the composition of the forest mosaic. The transition between deciduous dominance and coniferous dominance occurs in a fire cycle > 200 yr. Although pure deciduous stands tend to disappear during long fire cycles, the proportion of mixed stands remains relatively constant. Prediction of the forest composition for longer fire cycles is complicated by the interaction between post-fire composition and stand vulnerability to spruce budworm outbreaks. 相似文献
448.
Toshihiko Sato 《Ecological Research》1994,9(1):77-84
Stand structure and regeneration pattern were examined inAbies sachalinensis coastal forest in northern Hokkaido. In the forest a similar phenomenon to the wave regeneration in subalpine forests has
been found. Wave regeneration has been reported for montaneAbies forests in central Japan and North America. Differences and similarities between wave-type stands in this coastal forest
and wave-regenerated montane forests were clarified.
The shift of dead tree zone, stand structure and regeneration pattern in wave-type stands are the same as in subalpine wave-regenerated
forests. High density of individuals is considered to be an internal factor which causes stand-level dieback and also enables
the stands to persist in the severe environment in both forests.
A difference between wave-regenerated forests andA. sachalinensis wave-type stands is the number of dead tree zones, which is only one in wave-type stands. Changes of regeneration patterns
ofAbies sachalinensis with environmental gradient from seaward to inland were related to this difference. 相似文献
449.
Scott D. Roberts 《Trees - Structure and Function》1994,8(6):263-267
Lack of annual growth ring production at the base of branches in the lower portion of the crown is a commonly observed phenomenon. In this study, branches with missing rings were found on 47 of 49 Abies lasiocarpa trees sampled. The number of missing rings on the lowest live branch in the crown averaged 12, and ranged as high as 28. The lower one-third of the live crown tended to consist of branches without rings; these branches contained an average of 30% of the total crown leaf area. The ratio of foliage weight to total branch weight, in combination with position of the branch in the canopy, was an effective discriminator of non-ring producing branches. This suggests that both structural and environmental factors influence the cessation of ring production. The potential ecological implications of branches that fail to produce rings are discussed. 相似文献
450.
J. Kreike 《Plant molecular biology》1990,14(5):877-879
A method is described for the isolation of DNA from spruce and fir, starting with 3 to 5 apices (5 mg material). Apices are prepared manually from dormant buds harvested in summer and autumn, which are homogenized in 30 l buffer containing 1% SDS. The DNA is extracted with phenol and precipitated with ethanol. Agarose gel electrophoresis and Southern hybridization show that its molecular length is ca. 30–40 kb and that it is readily digested with various restriction enzymes. The method is very fast, it does not need CsCl centrifugation and is therefore suited for the analysis of large numbers of individual trees. Moreover, the buds can be collected all over the year. The yield of the method is up to 30 g of high molecular weight DNA, enough to do several digests and hybridizations. 相似文献