本研究主旨為評估人工林內孔隙栽植闊葉樹種苗木其生長潛力及形態性狀之變化。試驗地（北緯23°40’33”，東經120°46’23”）位於臺大實驗林溪頭營林區，為1938 年所建造之柳杉林，砍除間植麻竹後形成45 個大小、形狀不同之孔隙，冠層開闊度自13.2％至30.6％不等。在2005 年春天，每個孔隙栽植由6 種臺灣原生樹種瓊楠、大葉釣樟、狹葉櫟、青剛櫟、三斗石櫟及栓皮櫟各一株苗木所組成之栽植群。自2005 年至2009 年期間連續觀測各孔隙的冠層開闊度，另選其中11 個孔隙連續監測微環境因子之動態。2009 年調查苗木的生長表現及形態性狀。結果顯示，冠層開闊度在4 年間沒有顯著變化。栽植苗木的高度及直徑生長大致是在小孔隙生長較劣，且與冠層開闊度呈正相關，隨著孔隙的擴大而生長較佳。幹形也以大孔隙苗木較為粗壯，側枝數則以栽植在大孔隙者較多的傾向。進一步分析光入射量與土壤水分狀況對苗木生長及形態之影響，顯示二者各具其效應。樹種間則存有遺傳差異，致生長表現及形態變化在不同大小孔隙間或微環境因子下之變化趨勢並不全然相同。

The purposes of this study were aimed to assess the growth potential and morphological changes of broad-leaved tree seedlings planted in the various size gaps in a plantation, which was located at Chitou, Experimential Forest, NTU, central Taiwan (23o40’33”N, 120o46’23”E). Most trees in this plantation were Japanese sugi (Cryptomeria japonica), which was established in 1938.Forty-five various size and shape gaps were created after cutting Ma bamboo (Dendrocalamus latiflorus)which was irregularly propagated in the plantation. The canopy openings of those gaps were ranged from 13.2% to 30.6%. In spring of 2005, one seedling of every 6 native broad-leaved trees were planted in each gap, named Beilschmiedia erythrophoia, Lindera megaphylla, Cyclobalanopsis stenophylloids, Cyclobalanopsis glauca, Pasania hancei, and Quercus variabilis. During 2005 to 2009, we set the sensors to monitor the microenvironmental conditions in 11 of 45 gaps. In 2009, we measured the growth performances and morphological traits of planted seedlings. The results indicated that the canopy openings based on 9 time observations were changed negligibly. The height and diameter growth and the morphological traits in small gaps were poor and mostly improved as gap
size increased. We also assessed the effects of incident light and soil moisture on the growth and morphology of all planted seedlings, the regression curve showed that the differences in some traits of seedlings were attributed to the light intensity and also the increased amount of available soil moisture in gaps. However, species were differently affected by the combined effects of genetic control and microenvironmental conditions.