Tèxte anglés de traduire :
Sequoia sempervirens
Descripcion
Ecologia
Tèxte original
Coast redwoods are resistant to insect attack, fungal infection, and rot. These properties are conferred by concentrations of terpenoids and tannic acid in redwood leaves, roots, bark, and wood.[16] Despite these chemical defenses, redwoods are still subject to insect infestations; none, however, are capable of killing a healthy tree.[16] Redwoods also face predation from mammals: black bears are reported to consume the inner bark of small redwoods, and black-tailed deer are known to eat redwood sprouts.[16]
The oldest known coast redwood is about 2,200 years old;[17] many others in the wild exceed 600 years. The numerous claims of older redwoods are incorrect.[17] Because of their seemingly timeless lifespans, coast redwoods were deemed the "everlasting redwood" at the turn of the century; in Latin, sempervirens means "ever green" or "everlasting". Redwoods must endure various environmental disturbances to attain such great ages. In response to forest fires, the trees have developed various adaptations. The thick, fibrous bark of coast redwoods is extremely fire-resistant; it grows to at least a foot thick and protects mature trees from fire damage.[18][19] In addition, the redwoods contain little flammable pitch or resin.[19] If damaged by fire, a redwood readily sprouts new branches or even an entirely new crown,[18][16] and if the parent tree is killed, new buds sprout from its base.[16] Fires, moreover, appear to actually benefit redwoods by causing substantial mortality in competing species while having only minor effects on redwood. Burned areas are favorable to the successful germination of redwood seeds.[18] A study published in 2010, the first to compare post-wildfire survival and regeneration of redwood and associated species, concluded fires of all severity increase the relative abundance of redwood and higher-severity fires provide the greatest benefit.[20]
Redwoods often grow in flood-prone areas. Sediment deposits can form impermeable barriers that suffocate tree roots, and unstable soil in flooded areas often causes trees to lean to one side, increasing the risk of the wind toppling them. Immediately after a flood, redwoods grow their existing roots upwards into recently deposited sediment layers.[21] A second root system then develops from adventitious buds on the newly buried trunk and the old root system dies.[21] To counter lean, redwoods increase wood production on the vulnerable side, creating a supporting buttress.[21] These adaptations create forests of almost exclusively redwood trees in flood-prone regions.[16][21]
The height of S. sempervirens is closely tied to fog availability; taller trees become less frequent as fog becomes less frequent.[22] As S. sempervirens' height increases, transporting water via water potential to the leaves becomes increasingly difficult due to gravity.[23][24][25] Despite the high rainfall that the region receives (up to 100 cm), the leaves in the upper canopy are perpetually stressed for water.[26][27] This water stress is exacerbated by long droughts in the summer.[28] Water stress is believed to cause the morphological changes in the leaves, stimulating reduced leaf length and increased leaf succulence.[24][29] To supplement their water needs, redwoods utilize frequent summer fog events. Fog water is absorbed through multiple pathways. Leaves directly take in fog from the surrounding air through the epidermal tissue, bypassing the xylem.[30][31] Coast redwoods also absorb water directly through their bark.[32] The uptake of water through leaves and bark repairs and reduces the severity of xylem embolisms,[33][32] which occur when cavitations form in the xylem preventing the transport of water and nutrients.[32] Fog may also collect on redwood leaves, drip to the forest floor, and be absorbed by the tree's roots. This fog drip may form 30% of the total water used by a tree in a year.[28]
Traduccion del tèxte anglés :Partida eissida de l'article anglés
De mai, los sequòias contenon pauc de pega o de resina inflamabla. S'es damatjat per un incendi, un sequòia fach aisidament germenar de nòvas brancas o autanplan una corona entièrament nòva. Se l'arbre parent es tuat, de nòus borrons gisclan de sa basa. De mai, los incendis semblan en realitat profechar als sequòias en provocant una mortalitat substanciala en çò de las espècias concurrentas tot en avent sonque d'efièches menors sul sequòia. Las zònas cremadas son favorablas a la germinacion capitada de granas de sequòias. Un estudi publicat en 2010, la primièra a comparar la subrevida e la regeneracion dels sequòias e de las espècias associadas après un incendi, a conclusit que los incendis de tota gravetat aumentavan l'abondància relativa dels sequòias e que los incendis de gravitat mai elevada estançonen los mai benefics.
coast Douglas fir = avet de Douglas costièra (sosespècia de l'avet de Douglas)
Pacific madrone = arboç pacific" ???
tanoak = chêne à tan (fr) = "garric de tan" ?
western hemlock = "Tsuga de l'Oèst" e "Pin d'Oregon" ?
redwood sorrel = "agreta/vinheta del sequòia" ?
spotted owl = "cavèca pigalhada" ?
marbled murrelet = "guilhaumet marbrat" ?
black bear /
american black bear = "ors negre" o "ors negre american" (d'
Ors (mamifèr))
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