台中地區稜果榕物候之研究

Abstract

本研究探討台中地區樹德公園與大坑地區雌雄異株稜果榕 (Ficus septica Burm. f.) 於不同生育地的物候反應、雌雄株族群物候及榕果生產策略之性別分化，以及稜果榕與稜果榕小蜂 (Ceratosolen jucundus Grandi) 共生授粉生態之探討。於台中地區共發現4種稜果榕非授粉蜂，分別為Philotrypesis sp1.、Philotrypesis sp2.及Sycoscapter sp.及一種unknown genus sp.。物候調查由2007年11月至2009年4月，結果顯示台中地區之稜果榕成熟葉量呈明顯季節變化，春、夏2季成熟葉量最高，在冬季最低，展、落葉主要發生於冬春季與夏秋季交際時期。不同生育地、不同性別族群之葉候無明顯差異，榕果物候呈現明顯性別分化，樹德公園與大坑地區稜果榕雌株之榕果生產與2氣象因子無顯著相關，樹德公園之雄株總榕果量與2氣象因子呈顯著正相關，而大坑地區稜果榕雄株與氣溫呈顯著負相關，與累積降雨量相關不顯著。兩生育地之稜果榕雌株總榕果生產量與完整果季量皆低於雄株。稜果榕之榕果生長曲線、在物質(重量)與體積關係亦反映出性別分化現象，雌株對於單一榕果之生產投入較多的資源，隨著榕果發育，榕果乾重與乾體積比例亦增加；雄株對單一榕果生產之投資較少，隨榕果發育，榕果乾重與乾體積比例大致呈一定值。樹德公園稜果榕雌、雄株雌花期榕果幾乎全年不間斷，雌、雄株雌花期榕果量呈現顯著正相關，榕果生產高峰多有重疊現象。雄株雄花期榕果出現時期皆能與雌、雄株之雌花期榕果配合，且調查結果顯示雌、雄株雌花期榕果大多能成功授粉或被產卵發育至間花期，反映樹德公園之授粉蜂族群數量可達良好授粉共生關係。雄株於乾燥、低溫的冬季仍可生產雌、雄花期榕果，由雄花期羽化之授粉蜂可於樹德公園延續自身族群。大坑地區雌、雄花期榕果生產高峰時期大致與樹德公園相似，但花期較短暫零星，雄花期榕果出現較多且較長之開花休止期，顯示在此時期缺乏授粉蜂羽化，反映大坑地區稜果榕與其授粉蜂的授粉共生關係可能需要更多的雄株維持。結果顯示不同生育地稜果榕的榕果生產亦不同，其對授粉蜂族群維持有直接的影響，在較佳生育地環境，稜果榕族群可以較少的雄株維持其授粉蜂族群世代延續；而於干擾較大的生育地環境下，雄榕果生產減少易使授粉蜂族群數量受威脅，進而降低雌榕果授粉，影響稜果榕與其授粉蜂之授粉共生關係。

During November. 2007. to April. 2009. (totally 18 months). Dioecious Ficus septica Burm. f. has been choosed to be the material in this study. The purposes of the study is to investigate the affection of phenology at different habiat. We discuss the effect of different sexual population phenology, the different investment strategy between female or male syconia production and the pollination ecology between F. septica Burm. f. and they pollinator wasp (Ceratosolen jucundus Grandi) at Taichung. The results shows that F. septica Burm. f. occur tender leaves and falling leaves from spring to summer and autumn to winter also. In spring and summer, F. septica Burm. f. have the largest number of mature leaves in Taichung. The mature leaves and total syconia number at Shu-Te Park with average temperature and precipitation during the investigation day have remarkable positive correlation; and the number of mature leaves and total syconia has remarkable positive correlation too, which has the same influence in the quantity variability. The number of mature leaves at Dacan area with two meteorological factors have remarkable positive correlation. However, the number of total syconia with two meteorological factors has remarkable negative correlation. The leaf phenology result shows that there has no remarkable difference at sexual population in different habitat, but shows that obvious sexual specialization at syconium phenology and syconia production. Female trees' total syconia with two meteorological factors have no correlation between Shu-Te Park and Dacan area. The numbers of total syconia of male trees at Shu-Te with with two meteorological factors have remarkable positive correlation. The number of total syconia of male trees at Dacan with average temperature have remarkable negative correlation and with precipitation have no correlation. The quantity of total syconia production and the times of round syconia production of male population are much higher than female population. The growth curve and the syconia (wet or dry) volume versus syconia (wet or dry) weight for female tree reflect the sexual specialization at the investment of production on syconia. Female tree pay more resource in single female syconium. When female syconium developed, the dry volume and weight ratio will increase in a geometric progression. Male tree pay few resource in single male syconium, when a male syconium developed, the dry volume versus weight ratio is immovable. The quantity of B phase syconia at Shu-Te Park showed that they could almost produced continually. There has remarkable positive correlation between the number of B phase female and male syconia, and they often occur the overlap period when the peak of high quantity. The D phase high quantity peaks in male trees always could match the high quantity peaks of B phase syconia in female or male trees, and the B phase syconia almost could developed successfully to C phase syconia at Shu-Te Park. The result reflect the pollinator population quantity at Shu-Te Park had a stable state and had a fine pollination ecology with F. septica Burm. f.. Male tree could produce B or D phase syconia even in winter that the period has lower temperature and rainfall so that the pollinator could oviposition by entence local male trees with D phase syconia to maintain the pollinator population at Shu-Te Park. The high quantity peaks of B and D phase syconia at Dacan area were similar with She-Te Park, but the period of female or male flower season are seldom, and male population had more intervals with non D phase flower season. This shortage would the loss number of pollinator wasp. The phenomenon showed that to maintain the pollinator population would need more male trees to support and fine pollination ecology between F. septica Burm. f. and their obligate pollinator. The statistics showed the production of syconia were different between different habitat that will affect the population of pollinator directly. In better habitat F. septica Burm. f. could use few plants to maintain the pollinator filial generation; in highly disturbed habitat (ex: suffered insect pest), the production of male syconia decrease in male trees could endanger the local pollinator population size and decrease the pollination in female syconia, and affect the symbiosis pollination ecology between F. septica Burm. f. with their obligate pollinator. Four species of non pollinator wasps were discovered on F. septica Burm. f., they are Philotrypesis sp1., Philotrypesis sp2., Sycoscapter sp. and a unknow species.