The Seed Rain in a Subtropical Rain Forest, Fushan, Northern Taiwan

• Main Authors: Chia-Hao Chang-Yang, 張楊家豪
• Other Authors: Chang-Fu Hsieh
• Format: Others
• Language: zh-TW
• Published: 2004
• Online Access: http://ndltd.ncl.edu.tw/handle/94434963877609276224

碩士 === 國立臺灣大學 === 生態學與演化生物學研究所 === 92 === The purpose of this study is to understand the temporal and spatial variation of the seed rain in a subtropical rain forest of Fushan, northern Taiwan, and try to probe into the reproductive strategies and regeneration mechanisms of dominant tree species. A total of 87 0.5-m2 seed traps were placed in a 25-ha plot established in Fushan Subtropical Rain Forest. All seeds, fruits, seed-bearing fruit fragments, and flowers > 1 mm in diameter falling into the traps have been collected every week from Sept. 2002 to Mar. 2004. All samples were identified to species and separated into mature fruits, mature seeds, capsules, fruit fragments, immature fruits, and flowers. The viabilities of all mature seeds were also investigated in the meantime. All seeds were counted and sorted into 67 species, belonging to 37 families and 58 genera. There were 6877 seeds collected from 87 seed traps, and the biomass of falling fruits and flowers was 0.26 t/ha and 0.11t/ha during 2003. The highest biomass of the seed rain belongs to Limlia uraiana and the largest amount belongs to Schefflera octophylla. The onset and duration of seed rain varied considerably among each species in this forest and that can be categorized into three types: (1) Apr. to Jun., (2) Sept. to Dec., and (3) fruit falling all the year. There are only 3 species whose fruits fall all year round, 5 species during Apr. to Jun. and others during Sept. to Dec. Species with the largest potential fruit amount was Limlia uraiana, and the next was Castanopsis carlesii, but the successful fruiting rates of these two species were less than 0.1%. Species with the highest successful fruiting rate was Lagerstroemia subcostata, and the next was Glochidion acuminatum. A large proportion of fruits are immature fruits in species. Percentage of seed viability is quite different among main species, and ranges from 26% to 99%. The reproductive strategies of the dominant forest tree species are quite different from each other. Species like Schefflera octophylla and Glochidion acuminatum produce lots of seeds but with worse quality to overcome the hazards in each stage of fruiting. On the other hand, Machilus thunbergii, Machilus zuihoensis, and Litsea acuminate produce better quality seeds for their regeneration. The successful fruiting rates of Limlia uraiana and Castanopsis carlesii are extremely low. More researches are needed to understand the role of seed rain in their regeneration.