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不同光度環境對三種海岸林樹種苗木生理之反應 Physiological Responses of Three Coastal Tree Species Seedling on Different Light Environments
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| 作者 |
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許立勳 |
| 學校系所 |
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中興大學森林學系所 |
| 地點 |
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全臺 全部
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| 研究內容 |
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[ 摘要 ]
為改善木麻黃純林之林分結構，許多學者提出複層林之營造，以達到海岸林穩定林相之目的。本研究以人為不同遮陰之處理，探討海檬果(Cerbera manghas)、恆春山枇杷(Eriobotrya deflexa f. koshunensis)和蘭嶼羅漢松(Podocarpus costalis)等三種不同生態習性之海岸樹種對不同光度之生理反應，提供海岸複層林營造時，依不同孔隙選擇樹種之參考。
研究結果顯示海檬果於各光度處理均有較大的苗高及地徑淨生長量，別達到29 cm及6 mm；而蘭嶼羅漢松則呈現較低的生長量。在植株單一葉片形態變化上，恆春山枇杷表現出最高的形態可塑性。光合特性顯示三樹種以全光處理者之光飽和點都介在700〜900 μmol photon m-2 s-1之間，而海檬果及恆春山枇杷全光處理者也表現出較大之最大光合作用速率，分別為10.26及10.78 μmol CO2 m-2 s-1。葉綠素螢光日變化顯示三樹種全光處理者皆明顯受到光抑制，其正午之Fv/Fm值皆下降至0.75以下，而ΦPSⅡ值則下降至0.70以下。以95 %遮光處理之三樹種進行人工光誘導光抑制，結果則顯示海檬果對高光之忍受及調節能力較強，在最強光照階段時，其光化學消散比例仍可維持在0.5左右。而反射光譜之結果則顯示海檬果及蘭嶼羅漢松之高光處理者有較高程度的葉黃素循環，其PRI值大約在-0.15左右。葉片色素方面，蘭嶼羅漢松表現出最高的生理可塑性。
綜合上述之結果，海檬果表現出耐陰性樹種之特性，適於栽種於木麻黃林下相對光度5〜40 %之間的孔隙環境；而恆春山枇杷及蘭嶼羅漢松則具有較佳的形態及生理可塑性，可廣泛應用於不同光度的林下環境，適於栽種於木麻黃林分中相對光度40〜60 %之間的孔隙或是林緣處。
[ 英文摘要 ]
In order to improve the stand structure of Casuarina pure stand, many scholars proposed the building of multi-storied stand to obtain the purpose of stabilizing the seacoast forest stand. This study discussed the physiology response of Cerbera manghas, Eriobotrya deflexa f. koshunensis and Podocarpus costalis having different ecology habit to different light intensity by different artificial treatment of shading, to provide the reference of the tree species selecting when building multi-storied stand in different gaps.
The experiment results indicate that C. manghas in each light treatment having the greater net height growth and basal diameter growth, the maximum value were 29 cm and 6 mm respectively; P. costalis shows the lower growth. The change of morphology of single leaf, E. deflexa f. koshunensis shows the highest morphology plasticity. The characteristic of photosynthesis indicate that light saturation point of three species seedling growthing under full sunlight were between 700〜900 μmol photon m-2 s-1, and the seedlings of C. manghas and E. deflexa f. koshunensis growthing under full sunlight show greater maximum photosynthetic rate were 10.26 and 10.78 μmol CO2 m-2 s-1 respectively. The part of diurnalvariation of chlorophyll fluorescence indicate that three species seedling growthing under full sunlight were all show that suffering photoinhibition obviously, and their midday value of Fv/Fm and ΦPSⅡat were below 0.75 and 0.70 respectively . The result of artificial lighting-induced photoinhibition indicate that in each species seedling growthing under 5 % full sunlight, C. manghas has better ability of enduring high light and adjustment, their energy allocation of photochemical quenching could maintain about 0.5 at the strongest light intensity level. The result of spectral reflectance indicate that seedling growing under high light of C. manghas and P. costalis had higher xanthophyll cycle level, their value of PRI were about -0.15. The part of leaf pigment indicate that P. costalis shows the highest physiological plasticity.
Summarizing the above result, C. manghas shows the characteristic of shade-tolerant tree species, being suitable for planting at the gaps of beefwood stand which light intensity were between 5〜40 % full sunlight; E. deflexa f. koshunensis and P. costalis having better plasticity of physiology and morphology, could adaptate much different light environment, being suitable for planting at the gaps or edge of beefwood stand which light intensity were between 40〜60 % full sunlight. |
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