| Summary: | 碩士 === 中興大學 === 森林學系所 === 95 === Broussonetia papyrifera is an expansive distribution tree species from medium to low elevation of Taiwan. The habitat of B. papyrifera has extreme differentiation in light environments. In order to understanding adaptation mechanism of B. papyrifera to different light intensity and water status, we set various light and water treatments and observed the responses on phenology and physiology.
Results revealed that, B. papyrifera had well performance in shade and shown several characteristics such as high specific leaf area（323.90 cm2 g-1）, low light compensation point（7.01µmol m-2s-1） and chlorophyll a/b ratio （2.46）of shade-tolerance species. B. papyrifera also shown the ability of fast recovery after irradiated by high light. Therefore, B. papyrifera which grown in high light environment shown the well photosynthetic capacity and mechanism of dissipation. So B. papyrifera acclimated broadly to different light environment and distributed from sunlit openness area to understory of windbreak forest.
B. papyrifera had the best performance in well-watered treatment. Plants in water-stressed shown more tolerance in photosynthetical ability and better modulated ability to low water potential . The Ci/Ca ratio was between 0.5 and 0.8, so that the reduction in photosynthetic rate by water stress can be attributed to stomatal limitation. When suffered drought stress, B. papyrifera prevented water lose by closing stomata, it’s hairy leaf and defoliation may also assist in acclimatized to drought.
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