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-les, ki se tvori v mladostnem obdobju, odvisno od vrste, 5-30 let.

- problematičen pri vrstah, ki v mladosti hitro rastejo (topol, breza), medtem ko je pri počasi rastočih»sencovzdržnih« (jelka) njegov vpliv zanemarljiv. -les, ki se tvori v mladostnem obdobju, odvisno od vrste, 5-30 let.

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-les, ki se tvori v mladostnem obdobju, odvisno od vrste, 5-30 let.

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  1. - problematičen pri vrstah, ki v mladosti hitro rastejo (topol, breza), medtem ko je pri počasi rastočih»sencovzdržnih« (jelka) njegov vpliv zanemarljiv. -les, ki se tvori v mladostnem obdobju, odvisno od vrste, 5-30 let. -krajša vlakna z velikim mikrofibrilarnim kotom, ki povzroča zelo veliko osno (vzdolžno) nabrekanje in krčenje. juvenilni/mladostni les srčevina • Zaradi tehnološko manjvrednega juvenilnega lesa, mnogokrat visoke koncentracije reakcijskega tkiva in razkroja, je srčevina oz. debelna sredica tehnološko manj vredna in jo pred nadaljnjo predelavo lesa v vrednejše izdelke praviloma odstranimo.) Nima kasnega lesa. Zato se branike neizrazite, gostota lesa pa večinoma nižja od zrelega (adultnega) lesa. Je produkt mladega kambija in dobre oskrbljenosti z rastnim hormonom. Juvenilnemu lesu v debelni sredici je analogen krošnjev les.

  2. JUVENILNI LES Juvenile wood has a tendency for development

  3. JUVENILNI, ZRELI, STAROSTNI LES

  4. the height growth of a tree is traceable to production of new cells at the tip of the main stem and branches, and that diameter growth results from cell division in a 1-cell-wide layer of cells that sheath the main stem, branches, and roots. Because of this, the distance of any one growth increment from the center of the tree varies by height along the stem. For instance, a new growth ring found near the ground level or butt of a very large tree might represent the 100th year of growth at that height above ground, but only the third growth ring near the top of the main stem. Thus, much of the wood comprising the ring will be “normal, mature” wood, while the portion of the ring (that closest to the top of the tree) will be juvenile wood. This is true regardless of tree age. As long as a tree continues to grow in height, it continues to produce juvenile wood it shrinks and swells along the grain as moisture content changes, and strength is lower, and in some cases much lower, than mature wood of the same tree.

  5. juvenilni/mladostni les srčevina

  6. RAZPOKE -sušilne Zaradi krčenja lesa med sušenjem – napetosti v lesu! POŠKODBE -notranje razpoke Notranje napetosti v deblu. -mrazne Pogostejše pri listavcih z izrazitimi trakovi. -krožne Po letnici – spodnji del debla; jelka, hrast, kostanj, jesen, bukev,…

  7. KOLESIVOST - KROŽNE RAZPOKE radialne natezne napetosti•šibko mesto v živem drevesu

  8. BARVNE SPREMEMBE LESA Diskoloriran les/ mokrina Dvojna beljava Redko! Parenhimske pege breza, jelša, topol modrivost

  9. Obarvana jedrovina pri macesnu (a) in hrastu (b) ter neobarvana jedrovina pri jelki (c) in smreki (d). MOKRO SRCE okuženo z bakterijami, visoka vlažnost, Spremenjena permeabilnost, po sušenju lesa izgine. K. Čufar Normalen, neobarvan les bukovine (a, b) in diskoloriran les (c, d).

  10. UČNO GRADIVO • http://www.cpi.si/files/cpi/userfiles/Lesarstvo_tapetnistvo/5-NAPAKE_LESU.pdf

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