碩士 / 國立中興大學 / 生命科學系所 / 102 / Taiwan date palm, Phoenix hanceana Naudin (Arecaceae) is a native palm widely distributed in lowland Taiwan. Compared to most palm trees growing in tropical regions, P. hanceana found in subtropical habitats is a chilling tolerant indicator plant of its family. This species can serve as a valuable indicator to study the effects of global warming and changing environments and to provide a better understanding of how these changes affect the future populations of species in Arecacae and their growth strategies. In this study, P. hanceana from seven selected study sites in Taiwan (including western and eastern coastal areas and an outlying island), and cultivated individuals with different treatments, were used to monitor. The aim was to explore the association between growth strategy and leaf functional traits of P. hanceana and compare sapling growth responses. In addition, the tree age modeling and age estimation of local populations of P. hanceana were first reported.
Results showed that the plants growing in eastern Taiwan (Nantian, Guanshan and Baxiandong) had slower leaf growth rates. Among these sites, the plants growing in Baxiandong with relative shaded environments and those in the 21st- 25th plots of Guanshan had higher values of mature leaf length, leaf petiole length, leaf life span, leaf area and specific leaf area (SLA), but smaller leaflet frequency. The plants growing at Tongxiao, Dadu, Ludao (island) and Dulan had higher leaf growth rates. The two western sites (Dadu and Tongxiao) had experienced long term disturbance from human activity and fire, and gave the highest leaf dry matter content and low specific leaf area. Stepwise regression predicted that annual mean temperature, cumulative days of temperature < 12℃ per year, annual max temperature and min temperature were the main factors significantly related to leaf traits. A similar result was found from Canonical Correspondence Analysis (CCA). The seven study sites can be classified as coming from three geographic regions: eastern coastal, Guanshan, and western coastal regions. Among the classified ranks of the plant trunk height, there were no significant differences between leaf traits and trunk heights in western coastal and in Guanshan regions, but the leaf growth rate and leaf area increased with trunk height of the plants growing in eastern coastal region and the 14-16th plots of Guanshan. No matter leaf growth rate or green leaf number of any nursery saplings increase as trunk height increases. Those plants cultivated in eastern Taiwan treated with [sunny + moist] had a higher growth rate and green leaf number; while the plants treated with [sunny + water logging] had the shorter leaf life span than the others. The seasonal growth surveys during 2011 to 2013 showed that the highest leaf growth rate appeared in the summer of 2012, while the slowest one was in the winter of 2012. In summer and in fall of 2012, leaf growth rate was faster than those of the previous year. This study revealed that P. hanceana has different growth strategies in response to different environments and seasonal changes, and these responses may affect the trunk height. Moreover, temperature is the most important factor for palm growth. Light shapes the leaf. Precipitation promotes leaf growth, and the rainy days affect the leaf growth strategies: to increase the leaf number or to elongate leaf length. However, if precipitation is excessive, and the trunk bases are soaked, gas exchange rates are reduced, thus reducing leaf longevity.
Based on the growth modeling of P. hanceana constructed in this study, the young tree will not form a significant trunk until the growth of the 79th leaf. It is estimated that the ages of the existing populations of P. hanceana in Taiwan are at least 94- 273 years. Estimation of the oldest trunk age allows inference of the minimum local population survival time. In summary, these results of growth strategies and plant age composition of this species provide valuable insights for a better understanding of plant adaptive plasticity and for future conservation.
| Identifer | oai:union.ndltd.org:TW/102NCHU5105063 |
| Date | January 2014 |
| Creators | Su-Ya Liao, 廖思雅 |
| Contributors | Chiou-Rong Sheue, 許秋容 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 132 |
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