溪頭地區柳杉人工林不同冠層開闊度之微環境變化、種子發芽及苗木之生長表現

Microenvironmental Variation, Seed Germination and Seedling Growth under Different Canopy Openness in a Sugi（Cryptomeria japonica）Plantation at Shitou, Central Taiwan

張照群(Chao-Chun Chang)

指導教授 ： 郭幸榮

國立臺灣大學/生物資源暨農學院/森林環境暨資源學研究所/碩士(2008年)

https://doi.org/10.6342/NTU.2008.01790

摘要

本研究於台大實驗林溪頭營林區第二林班被插植麻竹的柳杉人工林分進行。試驗地於2005年砍伐散植的麻竹及整理藤蔓、雜草約1.8公頃，其後沿橫坡走向設置4條取樣帶，其中設立45個樣區，且於各樣區栽植青剛櫟(Cyclobalanopsis glauca)、狹葉櫟(Cyclobalanopsis stenophylloides)、三斗石櫟(Pasania ternaticupula)、栓皮櫟(Quercus variabilis)、瓊楠(Beilschmiedia erythropholia)及大葉釣樟(Lindera megaphylla)6種台灣原生闊葉樹種，每2個月觀察各樣區冠層開闊度的變化及所栽植苗木之生長表現。另於45個樣區中篩選設置11個微環境觀測站及10個種子播種區。微環境觀測站在試驗期間以連續性觀測光合作用有效輻射、氣溫、相對溼度、土壤溫度及土壤水勢5項因子。結果顯示冠層開闊度為影響陽光入射量的最主要因子，也影響日夜溫差、相對溼度和土壤溫差等微環境因子的變化。然土壤水勢並未受冠層開闊度的顯著影響。
5種闊葉原生樹種的發芽試驗顯示在林地的發芽率未顯著降低，但發芽速率則只有狹葉櫟未顯著延長，青剛櫟、川上氏石礫(Pasania kawakamii)、瓊楠及台灣雅楠(Phoebe formosana)4樹種則明顯延遲。各個樹種發芽當年的幼苗在不同冠層開闊度下皆有70％以上的存活率，且樣區間並無顯著差異。幼苗的當年生長量可能受種子所貯存的養分較多之影響，未受微環境因子及雜草競爭影響而改變，因此高生長及直徑生長量在不同開闊度下無明顯變化趨勢。
栽植苗木中，青剛櫟、狹葉櫟及三斗石櫟的苗高及苗徑生長量皆隨日平均光量之上昇而增加，表示在此期間光量為影響生長的主要因子。三斗石櫟及瓊楠的高生長皆與日平均光量和土壤水勢的複因子效應建立良好相關性。而大葉釣樟的直徑生長則與土壤水勢有線性相關。

關鍵字

原生闊葉樹種 ； 冠層開闊度 ； 微環境 ； 光合作用有效輻射 ； 氣溫 ； 相對溼度 ； 土壤溫度 ； 土壤水勢 ； 種子發芽

並列摘要

The study site was located at Chitou district, Experimental Forest, National Taiwan University. Ma bamboos was cleared from about 1.8 ha of the study site and then the seedlings of 6 native hardwood tree species, Ring-cupped oak, Arishan oak, Nanban tanoak, Chinese cork oak, Red bark slugwood and Large-leaved lindera were planted on each of 45 sampling points of 4 sampling regions along the traverse direction. The canopy openness and seedling growth were measured every 2 months. Eleven microenvironmental observatories and 10 germination plots were set up among sampling points. The microenvironmental observations included continuous photosynthetically active radiance, air temperature, relative humidity, soil temperature and water potential. The results showed that the amount of incident radiation was largely affected by canopy openness. Canopy openness also influenced other micro-environmental factors such as diurnal differences in air and soil temperature and relative humidity, but not water potential.
The seed germination was tested for 5 native hardwood tree species, Ring-cupped oak, Arishan oak, Kawakami tanoak, Red bark slugwood and Taiwan phoebe. The germination rates did not differ between field germination plots and laboratory, whereas the germination vigor was significantly lower in field germination plots in all species but Arishan oak. Germinated seedlings of all species had similar survival rate higher than 70% regardless of canopy openness or germination plots. The growth of germinated seedlings was probably affected more by the nutrients stored in seeds than by microenvironmental factors and weed competition. Therefore, height and diameter growth showed no clear pattern with the changes in canopy openness.
The height and diameter growth of the planted seedlings of Ring-cupped oak, Arishan oak and Nanban tanoak increased with average photosynthetic active radiation (PAR), suggesting that PAR was the major factor of growth. Factorial analysis showed that the height growth of Nanban tanoak and Red bark slugwod was significantly related to the daily average quantum and water potential. The diameter growth of Large-leaved lindera was significantly correlated with water potential.

並列關鍵字

Native hardwood tree species ； Canopy openness ； Microclimate ； Photosynthetically active radiance ； Air temperature ； Relative humidity ； Soil temperature ； Water potential ； Seed germination

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