The Common Beech (Fagus sylvatica) in the Course of the Year
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| License | No Open Access License: German copyright law applies. This film may be used for your own use but it may not be distributed via the internet or passed on to external parties. | |
| Identifiers | 10.3203/IWF/C-1612eng (DOI) | |
| IWF Signature | C 1612 | |
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| Production Year | 1985 |
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| IWF Technical Data | Film, 16 mm, LT, 206 m ; F, 19 min |
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Transcript: English(auto-generated)
00:22
The beach, Fagus sylvatica, through the seasons.
00:43
As a typical central European tree, the beach is well adapted to the seasonal change from summer to winter. It forms large forests in Europe. The tall trunks are protected against weathering
01:01
by their smooth metallic grey bark. The young shoots are enclosed in buds. The buds at the apex of an annual shoot are largest. Towards the base, they become progressively smaller.
01:23
This is an example of apical dominance. In the scarred zone at the centre of the picture, the twig began its growth in the previous year. In early spring, plants on the beach forest floor are the first to turn green.
01:43
Invisible to our eyes, the sap begins to rise up the stem and into the tips of the highest buds. Morphologically, the beach stem is monopodial because the leading shoot is dominant. This also applies to the horizontally produced lateral shoots.
02:05
The terminal bud in each case continues the growth of the shoot. Short and long shoots are generally clearly differentiated.
02:20
Spring flowering plants take advantage of the period before the trees are in leaf. During the first warm days of March and April, they flower and complete their reproductive cycle very quickly. The forest floor vegetation indicates that the soil of this beechwood is basic and nutrient-rich.
02:47
Lesser celandine and oxlip, hepatica and ivy grow among the wood anemones. Meanwhile, the buds have elongated conspicuously.
03:00
The bud opens, the scales elongate by intercalary growth, those at the tip growing faster than those at the base. The young leaves folded up like fans appear and begin to enlarge and spread out. At the same time, the young shoot elongates
03:21
so that the paired bud scales are pushed farther apart. The shoot is developed after about five days, unfolding of the bud seen once again in time lapse. Within a day or two, the three buds have unfolded their leaves.
03:44
The leaf blades increase their surface area with continual growth movements. At the base of the young shoot, the short bud scales are still to be seen,
04:00
which will later leave behind a characteristic zone of scars. Here, the scars are already suberized, twigs exposed to the sun bear flowering buds. Generally, they are produced on short shoots, as in fruit trees.
04:25
Flowering buds are fatter than leaf buds. They open at the same time. Initially, young leaves appear, followed by male catkins, which push their way out between them. They are lateral branches of annual short shoots.
04:46
The pendant axis of the catkin is thickly beset at the end with individual flowers, each enveloped in a simple perianth. Every flower has some five to ten stamens, which release pollen.
05:07
The perianth, like this one on a young male flower, is fused and hairy. The male catkins hang below the horizontal leaf plane of a twig.
05:21
Wind or vibrations cause pollen to be released. While the male catkins are flowering, the female ones are developing. The female inflorescence is enclosed in membranous bracts
05:42
and in a cupule, having numerous tassellated projections. Within four days, it grows to a size of about one centimeter. Each of the paired female flowers has a pistil bearing three stigmata.
06:02
Papillae on the stigmata capture pollen from neighboring trees. Female and male catkins are born at different areas along the twig. Meanwhile, the young shoots have grown stronger. By May, the succeeding generation of buds has already been laid down.
06:25
At the tip is the leading bud of the twig, behind which is the axillary bud of the topmost leaf. Scales are still attached. Most of the bud scales have already fallen to the ground
06:40
and are lying among the flowering woodruff. The weight loss from an average tree is about two to four kilograms of biomass. At the end of May, the beech foliage has a yellow-green colour, since the cell walls are still translucent and the cells do not yet have their full chlorophyll content,
07:04
but photosynthesis is already well underway. During transpiration, the leaves give off water vapour to the atmosphere and enable the sap to be transported up to the highest twigs of the tree's crown.
07:20
Water and nutrients have in turn to be supplied from the soil via the roots. They frequently fuse with the roots of neighbouring trees, as one can see quite well in this exposed area. Many trees may be joined together in this way
07:41
so that the supply to each individual tree is shared. In the meantime, from April onwards, the previous year's beech nuts are germinating on the forest floor.
08:02
The cotyledons are still enclosed inside the nutshell and the hypocotyl lifts them up. Their whitish undersides contain storage materials which were used up during germination.
08:21
Their upper surfaces are rich in chlorophyll, which equips them well for photosynthesising on the shady forest floor. As the cotyledons spread out horizontally, they make optimum use of the available light. At the same time, the epicotyl extends upwards with the primary leaves.
08:44
Their blades expand by surface growth and they develop chlorophyll. Initially, along with the cotyledons and later on their own, they accumulate reserves during the summer for the following year.
09:06
The shoot ends its growth for the current year with the formation of a terminal bud. Fourteen days have elapsed since this seedling germinated.
09:28
Following last year's, beech seedlings appear in large numbers. This five-year-old plant, with its sparse growth, shows how hard it is for young plants to survive their early years
09:44
on the shady woodland floor. At the beginning of June, even the leaves in the crown are in competition for sunlight. The directional growth of the leaf stalks leads to the formation of a leaf mosaic,
10:02
which enables individual leaves to expose themselves optimally to the available sunlight. Young trees, which are shaded by older trees, spread their entire crown on one level. The stratification in the lower regions of older trees
10:22
is on the same principle. By contrast, the upper branches of the crown stand up like a besom in adaptation to direct insulation throughout the day. Favourable lighting conditions at ground level promote young plant growth
10:42
and thus contribute to renewal of the woodlands. Meanwhile, it is summer. The beech foliage is now dark green and leathery. The surface area of the leaves is no longer increasing.
11:05
Growth in length and girth of this year's shoot has long since finished. The cupules have also grown to maturity. Only the next year's buds continue to grow.
11:28
Growth increment in the beech depends on the quality of its situation. The beech can root deeply in this lussic soil. It is waterlogged below a depth of 60 cm as is shown by the small brown spots at the lower edge of the picture.
11:44
The loess is covered by a 6 cm layer of humus. It, in turn, is strewn with last year's forest litter. It is being decomposed by small animals, fungi and microorganisms.
12:07
Beech roots penetrate deep into the soil. The fine rootlets ramify throughout mul and topsoil. Their tips, seen here in close-up, have developed a symbiotic relationship with certain species of fungi
12:21
forming mycorrhiza. The fungal hyphae closely surrounding the young roots replace the root hairs. Mycelial strands extend from the fungus mantle surrounding the root. By the beginning of August, the beech cupules have become woody and brown.
12:46
During the ensuing weeks, maturation continues. The fruit of the arum are ripe. Summer is merging into autumn.
13:02
The martygon lily is also in fruit. It is now October. The nuts inside the cupules are ripe. The husk splits into four valves within about two days. It is a hygroscopic process brought on by desiccation.
13:32
An abscission layer is formed at the base of the beech nut. After release, two scars are left at the bottom of the cupule.
13:49
As the days grow shorter, the leaves begin to change colour. Chlorophyll decomposes. Xanthophylls and carotenoids remain behind. The final brown colour is produced by complex oxidation processes.
14:04
Afterwards, the leaves fall. The leaves on one tree do not all change colour simultaneously. The outermost leaves, most exposed to the sun,
14:20
begin to fade earlier than the shaded leaves at the base of the twigs inside the crown. Valuable constituents of the leaf, such as nitrogen and magnesium, are first withdrawn into the interveinal areas and finally transported back down the main vascular bundles.
14:42
Once the abscission layer at the base of the petiole has been formed, the leaf may fall. A fresh scar remains behind. The stumps of the vascular bundles can be distinguished. The lower scars are already suberised.
15:06
The materials which have been withdrawn are stored in the stem and branches in readiness for next year's growth. When drought or early frost affects the leaves,
15:21
there's no time for the substances to be removed properly. In such cases, an abscission layer may not be formed and the leaves remain on the branch throughout the winter. Each year, a tree disposes of up to 50 kilograms of foliage. In addition, it sheds small branches, cupules and beech nuts.
15:43
This cast-off biomass decomposes over the years and its mineral constituents are again made available to the beech trees via the soil and the mycorrhizal symbionts. By November or December, the forest is leafless. The beeches are dormant.
16:00
Their tissues show only a minimum of activity. Cracks in the bark allow gaseous interchange to take place. The bark of a five-year twig has crevices
16:22
in which resting stages of insects or, as here, a greenfly egg are able to overwinter. The twigs of the current year are also enclosed in bark to guard them against desiccation and cold. Only small pores, known as lenticels,
16:41
allow gases to circulate in and out. On removing the bud scales, one can see that next year's leaves and flowers are already present.
17:02
Embedded in hairs, a male inflorescence nestles in the leaf axil. Another male inflorescence and, terminally, a female one. In this way, the buds are admirably equipped for overwintering.
17:21
Now, neither frost nor rime alternating with winter sunshine can damage them. The covering of snow over the soil is like an insulating blanket, sheltering the tree roots and the small organisms and protecting the woodlands during the winter.