| Summary: | 碩士 === 中興大學 === 森林學系所 === 99 === In recent years, it advocates ecosystem management and the restoration of degraded plantations in Taiwan. Therefore, we selected the understory of regeneration seedlings Schefflera octophylla and Psychotria rubra as test materials at the Dakeng area of Jiadongliao in Taichung. It treated with the different light environments such as full light, 40%, 20%, 5%, and the field of seedlings as the control group which measured the adaptation of different light environment on the morphology and physiology of seedlings, to offer the reference of restoration and the gardening landscape of tree species selecting.
The characteristics of morphology indicated the S. octophylla had better growth at the relative light intensity of 20-40% , P. rubra had better growth at the relative light intensity of 40%, the growth of S. octophylla and P. rubra at full light are limited. The characteristic of photosynthesis indicated the seedlings of S. octophylla and P. rubra growthing at the relative light intensity of 40% show maximum photosynthetic rate were 9.41 and 8.78 μmol CO2 m-2s-1 respectively, and the light saturation point of S. octophylla is between 500-800 μmol photon m-2s-1 in summer, while the light saturation point of P. rubra is between 200-400 μmol photon m-2s-1 in summer. The results of chlorophyll fluorescence indicated S. octophylla and P. rubra had lower Fv''/Fm'' (0.45) at the light intensity of 5% during the high light stage of artificial light-induced, and ΦPSⅡ were below 0.39 and 0.46 respectively. The daily variation of chlorophyll fluorescence indicated that S. octophylla influenced by light greater than temperature, and that P. rubra both influenced by high light and low temperature obviously. When the light increases, S. octophylla improve NPQ to dissipate excess heat, while P. rubra is through the xanthophyll cycle to dissipate excess heat, the value of PRI was lower in winter than in summer. The leaf pigment of S. octophylla and P. rubra increase with light intensity, and improve chl a/b and caro/chl, to adapt to different light environment.
Summarizig the above results, it suggested that S. octophylla being suitable for planting to the relative light intensity of 20-40%. However, P. rubra shows the characteristic of shade tree, being suitable for planting below the light environment of semi-shade.
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