台南市安平港復育五梨跤稚樹在不同光環境下之形質生長研究

Morphological growth of rehabilitated Rhizophora stylosa saplings under different light environment in Anping Harbour, Tainan City, Taiwan

安平港紅樹林復育計畫在1996及1998年兩次直插五梨跤（Rhizophora stylosa）胎生苗，本研究繼續於2005年7月調查分析9年及7年生稚樹在不同光環境下，樹高、地際直徑、枝下高、樹冠幅、各部位乾重、總乾重、生物量分配、枝條及地上部支持根形態之差異。結果顯示：生長在全光（相對光度100%）及半遮蔭環境（相對光度約67%）之9年生稚樹，無論樹高、枝下高、樹冠幅及各部位乾重等，均較生長在遮蔭處（相對光度約11%）者高；其中全株總乾重分別為5941.3及5191.6g，較遮蔭處者高約7-8倍。7年生之稚樹亦有相似結果，全光及半遮蔭環境生長之樹高分別達326.7及260.0cm，2者之生物量較遮蔭處者大約12倍。在不同光環境下生長之9及7年生稚樹葉重率（LWR）並無明顯差異，但生長於全光及半遮蔭環境之稚樹莖重率（SWR）明顯較低，而支持根重率（RWR）則較高。在全光及半遮蔭環境之2種年齡稚樹，枝條數、地上部支持根數及支持根角度均較高，而在不同光環境下之枝條平均角度則無顯著差異。以上這些特性顯示五梨跤稚樹在高光環境下會有較佳生長。 Anping harbour mangrove rehabilitative project involved the direct sowing of Rhizophora stylosa viviparous seedlings in 1996 and 1998. We surveyed and analyzed such items of sapling on tree height, root collar diameter, clear length, crown diameter, dry weight of each components, biomass allocation, branch and above-ground prop root characters of rehabilitated 9-year-old and 7-year-old R. stylosa saplings under different light environments in July 2005. The results indicated that the mean height, clear length, crown diameter, dry weights of each components of 9-year-old sapling which grown in full light (relative light intensity was 100%) and semi-shade (relative light intensity approximately 67%) environment were significantly higher than those grown under shade environment (relative light intensity approximately 11%). The total dry weight reached 5941.3 and 5191.6 g, respectively, a rate of growth nearly 7-8 times as fast as saplings growing under shade environment. The 7-year-old saplings had similar results, the biomass of saplings grown in full light and semi-shade environment nearly 12 times as much as saplings gown under shade environment. The leaf weight ratio (LWR) of saplings showed no significant difference between 3 light regimes, however stem weight ratio (SWR) of saplings were significantly lower than saplings grown under shad environment, but the prop root weight ratio (RWR) was increased. The branching number, prop root number and angles of saplings were significantly higher when grown in a fully light and semi-shade environment. However, the branching angles of saplings showed no significant difference between saplings grown in different light environment. These characters indicated that R. stylosa saplings have better growth performance when grown in higher light environment.

Anping harbour mangrove rehabilitative project involved the direct sowing of Rhizophora stylosa viviparous seedlings in 1996 and 1998. We surveyed and analyzed such items of sapling on tree height, root collar diameter, clear length, crown diameter, dry weight of each components, biomass allocation, branch and above-ground prop root characters of rehabilitated 9-year-old and 7-year-old R. stylosa saplings under different light environments in July 2005. The results indicated that the mean height, clear length, crown diameter, dry weights of each components of 9-year-old sapling which grown in full light (relative light intensity was 100%) and semi-shade (relative light intensity approximately 67%) environment were significantly higher than those grown under shade environment (relative light intensity approximately 11%). The total dry weight reached 5941.3 and 5191.6 g, respectively, a rate of growth nearly 7-8 times as fast as saplings growing under shade environment. The 7-year-old saplings had similar results, the biomass of saplings grown in full light and semi-shade environment nearly 12 times as much as saplings gown under shade environment. The leaf weight ratio (LWR) of saplings showed no significant difference between 3 light regimes, however stem weight ratio (SWR) of saplings were significantly lower than saplings grown under shad environment, but the prop root weight ratio (RWR) was increased. The branching number, prop root number and angles of saplings were significantly higher when grown in a fully light and semi-shade environment. However, the branching angles of saplings showed no significant difference between saplings grown in different light environment. These characters indicated that R. stylosa saplings have better growth performance when grown in higher light environment.