| – |
• Existing growth and yield plots of pure and mixed stands of Norway spruce (Picea abies (L.) H. Karst.) and European beech (Fagus sylvatica L.) were aggregated in order to unify the somewhat scattered sources of information currently available, as well as to develop
a sound working hypothesis about mixing effects. The database contains information from 23 long-term plots, covering an ecological
gradient from nutrient poor and dry to nutrient rich and moist sites throughout Central Europe. 相似文献
2.
Die bisher erarbeiteten Ergebnisse lassen sich wie folgt zusammenfassen:
| 1. |
Bei der Fichte korrelieren Jahrringbreite und Holzdichte und damit die wesentlichen Festigkeitseigenschaften, wie Biegefestigkeit,
Biege-E-Modul, Druckfestigkeit.
|
| 2. |
Die Holzdichte als wesentliche Eigenschaft steht in enger Beziehung zum Sp?tholzanteil.
|
| 3. |
Die Astst?rke korreliert direkt mit der Wachstumsgeschwindigkeit, d. h. ebenfalls mit der Jahrringbreite.
|
| 4. |
Astst?rkensumme und Jahrringbreite zusammen erkl?ren einen gro?en Teil der technischen Holzeigenschaften.
|
| 5. |
Durch Wert?stung kann ein Teil der negativen Wirkungen des schnellen Wachstums auf die Festigkeitseigenschaften ausgeglichen
werden.
|
| 6. |
Dies bedeutet allerdings nicht, da? die Holzdichte als wesentliches Merkmal an Bedeutung verliert.
|
| 7. |
Eine weitgehend zu erwartende Reihung ist also aus holztechnologischer Sicht eindeutig festzustellen:
|
| – |
— engringig und wertge?stet auf dem 1. Platz, verspricht also h?chsten Holzwert,
|
| – |
— engringig, nicht wertge?stetes Holz steht an 2. Stelle,
|
| – |
— weitringig, wertge?stet im Mittelfeld, nur knapp nach Position 2
|
| – |
— weitringiges, nicht wertge?stetes Holz verliert, mit Abstand an letzter Stelle stehend.
|
Results achieved till now may be summarized as follows:
| 1. |
With spruce, annual ring width is correlated with wood density, and thus with the essential strength properties such as bending
strength, bending-E-module, and tensile strength.
|
| 2. |
Wood density as an essential property is closely related to the share of late wood.
|
| 3. |
There is a direct correlation between knot size and growth rate, i. e. also annual ring width.
|
| 4. |
The sum of knot diameters and annual ring width together explain a large part of the technical wood properties.
|
| 5. |
High pruning may compensate for some of the negative effects of rapid growth on strength properties.
|
| 6. |
This, however, does not imply that wood density is becoming less important as an essential property.
|
| 7. |
From the wood-technological viewpoint, a largely to be expected ranking can be clearly established:
|
| – |
— narrow growth rings and high-pruned stands in first place, thus promising the highest timber value,
|
| – |
— narrow growth rings but not pruned comes second,
|
| – |
— wide growth rings and high-pruned ranks about in the middle, only slightly behind position 2,
|
| – |
— wood showing wide growth rings and not being from pruned trees falls way behind.
|
相似文献
3.
Der Wald ist für den Naturschutz
| – |
— aus grunds?tzlichen Erw?gungen,
|
| – |
— wegen seines hohen Wertes als Lebensraum für Pflanzen und Tiere,
|
| – |
— im Hinblick auf seinen gro?en Fl?chenanteil, auch in seiner Form als Wirtschaftswald von besonderer Bedeutung.
|
Die naturschutzfachlichen Anforderungen an eine naturvertr?gliche Waldbewirtschaftung lassen sich insbesondere mit Hilfe des
Arten- und Biotopschutzprogramms und anderer konzeptioneller Arbeiten immer besser formulieren; es bedarf aber noch weiterer
Grundlagenerhebungen, insbesondere einer ?kologischen Werterfassung im Wald. 相似文献
4.
| – |
• We aimed to better understand the genetic architecture of growth in E. globulus undergoing inbreeding by comparing families from selfing (SELF), open pollination (OP) and unrelated polymix crossing (POL)
of common parents. Stem diameter at breast height (DBH) was assessed at 4, 6 and 10 years after planting in a field trial. 相似文献
5.
| – |
• Carbon isotope composition (δ13C) is a complex trait involved in acclimation, adaptive processes and related to water use efficiency (WUE) and/or productivity. 相似文献
6.
| – |
• We present the results of a two-year (2007–2008) greenhouse study investigating the effect of water availability and nitrogen
fertilization on the growth, biomass partitioning, and foliar nutrient content of Abies fraseri (Pursh) Poir. 相似文献
7.
| – |
• Paternity was established in a field trial of Abies nordmanniana with open-pollinated (OP) offspring from a clonal seed orchard (CSO) comprising 23 clones. 相似文献
8.
| – |
• Fine root responses to potential climate change are relatively unknown in spite of their central role in ecosystem functioning. 相似文献
9.
| – |
• Mixed forests feature competitive interactions of the contributing species which influence their response to environmental
change. 相似文献
10.
| – |
• Radiata pine (Pinus radiata D. Don) is the main exotic plantation tree species grown in New Zealand for wood production and as such represents a significant
component of the terrestrial carbon cycle. 相似文献
11.
| – |
• Canarian Juniper woodlands, now very scarce, are rich in endemic and endangered plants. However, many aspects of juniper
regeneration are almost unknown. 相似文献
12.
| – |
• Effects of thinning on epicormics have rarely been demonstrated especially due to inaccurate surveying methods. 相似文献
13.
| – |
• The aim of our work was to homogenise the meteorological dataset of German ICP Forests Level II sites (n = 73) by the aid of interpolations based on climate data from the German meteorological network (DWD). 相似文献
14.
| – |
• Previous studies on competitive interactions among silver birch, Scots pine, and Siberian larch have not addressed the direct
importance of the species identity of nearby competitors. 相似文献
15.
| – |
• This study investigated the short-term changes in neutral genetic variation that would occur if a mature, second-growth,
black walnut (Juglans nigra L.) stand was harvested following either a diameter-limited or value-limited cutting regime. 相似文献
16.
| – |
• Multivariate statistical analysis was used to define different developmental stages for stone pine (Pinus pinea L.) considering tree size and cone production, without site-specific information. 相似文献
17.
| – |
• The vibration damping coefficient (tanδ) of wood is an important property for acoustical uses, including musical instruments.
Current difficulties in the availability of some of the preferred species call for diversification, but this comes up against
the lack of systematic damping coefficient data. 相似文献
18.
| – |
• We combined stem volume increment analysis with dendroecological tools to address two unresolved issues concerning oak dieback
in Mediterranean areas: early detection of changes in stand growth, and identification of mechanisms for observed growth declines. 相似文献
19.
| – |
• The Spanish fir (Abies pinsapo Boiss.) is a conifer endemic to southern Spain and belongs to a Mediterranean basin group of firs considered to be relict.
Megagametophyte storage proteins are a useful tool for the evaluation of genetic variability due to the haploid nature of
megagametophytes in conifers. 相似文献
20.
| – |
• To withstand and to recover from severe summer drought is crucial for trees, as dry periods are predicted to occur more
frequently over the coming decades. 相似文献
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