| Autor: |
Shrestha, Bharat B.1 pkjhaprof@yahoo.com, Luite, Dol R.1,2, Lamichhane, Dipak1,3, Jha, Pramod K.1 |
| Předmět: |
|
| Zdroj: |
International Journal of Ecology & Environmental Sciences. Dec2007, Vol. 33 Issue 4, p263-271. 9p. 1 Chart, 4 Graphs. |
| Abstrakt: |
Phenological activities of two canopy tree species (Engelliardia spicata Leschen. ex Blume and Fraxinus floribunda Wall.) and two subcanopy species (Myrica esculenta Buch.-Ham. ex D.Don and Lyonia ovalifolia (Wall.) Drude) of subtropical forest in central Nepal were examined for one year. Myrica esculenta is an evergreen species while other three species are deciduous. Water relations attributes were obtained from pressure-volume (P-V) analysis and the measurement of relative water content of leaves (RWCL) in each month. Canopy species put out their leaves earlier than subcanopy species but the latter retained leaves for a longer period during dry summer. Delayed greening in Lyonia ovalifoIia may prevent resource loss from young leaves by herbivory. Deciduous species, which either showed elastic adjustment (e.g. Engeihardia spicata) or had inherent drought tolerance (e.g. Lyonia ovalifolia), retained leaves during the early dry season (winter). Drought intolerant, deciduous Fraxinusfioribunda remained leafless for longer period (December - February) than other deciduous species but this plant produced new organs earlier during dry summer. Osmotic adjustment in the evergreen Myrica esculenta helped the plant to retain mature leaves and begin new growth during the dry season. There was trade off relationship between osmotic capacity to absorb water and tissue elasticity. No clear consistency exists in the differences of measured water relations parameters between canopy height and leaf forms with the apparent exception of relative water content at turgor loss point (RWCtlp) and osmotic adjustment. [ABSTRACT FROM AUTHOR] |
| Databáze: |
GreenFILE |
| Externí odkaz: |
|
