| Summary: | 碩士 === 國立臺灣師範大學 === 生命科學研究所 === 99 === Typhoon is the most common natural disturbance in Taiwan. Typhoon disturbance often caused high quantity of leaflitter accompanied by the loss of nutrients and reduced photosynthesis. Will the damaged trees adjust nutrient retranslocation to enhance photosynthesis and as such compensate typhoon damage? We studied the pattern of retranslocation of Helicia formosana Hemsl、Litsea acuminata (Bl.) Kurata , Meliosma squamulata Hance , and Castanopsis cuspidata (Thunb. ex Murray) Schottky var. carlesii (Hemsl.)Yamazaki cf. sessilis (Nakai) Liao in Watershed #1 of Fushan Experimental Forest between August and December 2010 which includes period before and after typhoon disturbance. Two typhoons affected Taiwan during the study period, one is typhoon Fanapi landed Taiwan in 19 September 2010 and typhoon Megi approached Taiwan in late October 2010. Both typhoons brought large amount of precipitation but high winds only occurred when typhoon Fanapi affected Taiwan. The result indicates that the two typhoons affected Fushan Experimental Forest differently with typhoon Fanapi had a greater impact than typhoon Megi. There was another leaflitter peak in November unassociated with typhoon disturbance. Helicia formosana and Litsea acuminata had high quantity of leaflitter following typhoon Fanapi whereas leaflitter of Meliosma squamulata and Castanopsis cuspidata peaked in November. In terms of nutrient retranslocation, following typhoon Fanapi the retranslocation efficiency of N and K declined, the efficiency of Ca and Mg increased and the efficiency of P showed little change. No clear pattern of changes in retranslocation was observed following Typhoon Megi. Several weeks after typhoon Fanapi, N retranslocation efficiency did not return to levels before the typhoon. Possibly the energy consuming retranslocaiton is not preferred at Fushan where typhoon disturbance may occur several times a year as such investment in retranslocation may lead to large nutrient and energy loss. Tree species differed significantly in typhoon versus non-typhoon induced leaflitter and even in different collections in non-typhoon period. The result indicates that species-specific leaf-litter collection is required for a full understanding of typhoon effects on nutrient retranslocation. Both the retranslocaiton efficiency and retranslocation proficiency of P were greater than N indicating that P is a more limiting element at Fushan Ecosystem.
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