| Autor: |
Shrestha, Bharat B.1 bhabashre@yahoo.com, Jha, Pramod K.1 pkjha@ecos.wlink.com.np, Zobel, Donald B.2 zobeld@science.oregonstate.edu |
| Předmět: |
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| Zdroj: |
International Journal of Ecology & Environmental Sciences. Jun2006, Vol. 32 Issue 2, p183-192. 10p. 1 Chart, 7 Graphs. |
| Abstrakt: |
Variation in phenology and water relations was studied in Pinus roxburghii Sarg. (chir pine), a co-dominant tree species in the Churia Hills of south-central Nepal. Measurements were carried out from September 1999 to February 2001, at a monthly interval except during the rainy season. Phenology, soil water potential at 15 cm (soilΨ15) and 30cm (soilΨ30) depth, tree water potential (predawn, ΨPD and midday, Ψmd), P-V curve analysis, xylem conductance (specific xylem conductance Ks and leaf specific conductance K1), and wood properties (wood water content WWC and density Dw) were measured. Leaf life span of chir pine was nearly 13 months.- New leaf growth and leaf fall occurred simultaneously during March - April. Lowest soil Ψ (-1.6 MPa) and tree ΨPD (-0.8 MPa) were recorded in March while the tree Ψ md(-1.7 MPa) was lowest in April. Before leaf fall began in February, there was sharp reduction in tree Ψmd (-1.6 MPa). During leaf expansion (March to May) tree ΨPD nearly remained stable (-0.8 to -0.7 MPa). Chir pine of Churia Hills had high dehydration tolerance as compared to other pine species. Higher wood water content and death of leaf tissue at the time of bud break were the important strategies to maintain favorable water status during the dry but phenologically active period. Chir pine showed close resemblance to trees of dry tropical forest in its seasonality of leaf production and shedding in response to soil moisture and tree water status. Greater access to soil water than associated tree species may be one of the major strategies used by chir pine to replace broadleaved dominant species in lower altitude, a succession observed in many forests of Himalayas. [ABSTRACT FROM AUTHOR] |
| Databáze: |
GreenFILE |
| Externí odkaz: |
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