Vegetation Composition and Structure in the Ecotone between Deciduous and Evergreen Broad-leaved Forests in an Upstream Region of Nantzuhsiensi, South-Central Taiwan

台灣中南部楠梓仙溪上游集水區內，於2005年1月至2006年2月間設立一處8.37公頃的森林動態樣區（楠溪樣區）。為了瞭解落葉林與常綠闊葉林交會帶的物種組成與結構，本研究選定楠溪樣區中西側稜脊上的台灣赤楊落葉林及鄰近的常綠闊葉林進行分析，研究範圍共計2.56公頃（256個10×10平方公尺的樣方），區分5個區塊，包含落葉林與兩林相邊界至常綠闊葉林林內的交會帶（0~10公尺、10~20公尺、20~30公尺與30~40公尺等）區塊。本研究估算各區塊中，每個樣方內木本物種的密度與底面積。總密度與總平均底面積在距離落葉林10~20公尺的常綠闊葉林區塊內達到最高。研究結果共記錄了52種木本植物，其中有50%出現在落葉樹林中，而有96%的種類則出現在常綠闊葉林中。台灣赤楊是本落葉林中優勢的物種，在常綠闊葉林則以長尾栲、長葉木薑子與薄葉柃木為優勢。台灣赤楊的密度與平均底面積在落葉林區塊中數量最高，越往常綠闊葉林內數量逐漸下降，至距離落葉林20~30公尺的常綠闊葉林區塊內則完全消失。這些結果反應邊際影響深度(DEI)為從兩種森林邊緣至常綠闊葉林內部20公尺。在落葉林中存在許多常綠闊葉樹的小樹，如長葉木薑子、假長葉楠、狹葉櫟、白新木薑子、大葉石櫟、青葉楠、大頭茶與屏東木薑子等物種。這些闊葉樹種將可能逐漸取代台灣赤楊落葉林，而改變落葉林的結構與物種組成。

關鍵字

生態交會帶；落葉樹林；常綠闊葉樹林；邊際影響深度；楠溪森林動態樣區

並列摘要

The Nansi forest dynamic plot, 8.37 ha, was set up during January 2005 to February 2006 in the upstream region of the Nantzuhsien River in south-central Taiwan. This study was conducted on the mid-western ridge of the Nansi plot in a transitional zone between an Alnus formosana deciduous forest and an evergreen broad-leaved forest to understand differences in species composition and vegetation structure in the ecotone between these 2 forests. We studied a total of 2.56 ha (256 quadrats) on the mid-western ridge of the Nansi plot, which we divided into 5 sections, including 1 section of deciduous forest and 4 ecotone sections (0~10, 10~20, 20~30, and 30~40 m away from the edge into the evergreen broad-leaved forest). Tree density and basal area were calculated based on the quadrat (10×10 m^2) of each section. Both the total density and mean basal area were highest in the section of 10~20 m. Fifty percent of the total recorded 52 species were found in the deciduous forest, and 96% were found in the evergreen broad-leaved forest. Alnus formosana was dominant in the deciduous forest, whereas Castanopsis carlesii, Litsea acuminata, and Eurya leptophylla were dominant in the broad-leaved forest. The density and mean basal area of A. formosana decreased along the gradient from the deciduous forest to the evergreen broad-leaved forest, and disappeared in the section of 20~30 m. These factors reflected the depth of edge influence (DEI) presenting 20 m into the interior of the evergreen broad-leaved forest. In the deciduous forest section, there were many small trees of evergreen broad-leaved species, e.g., L. acuminata, Machilus japonica, Cyclobalanopsis stenophylloides, Neolitsea sericea, Pasania kawakamii, M. zuihoensis, Gordonia axillaris, and L. akoensis. Thus, this A. formosana deciduous forest is likely to be gradually replaced by these evergreen broad-leaved tree species, and its vegetation structure and species composition are likely to change in the future.

並列關鍵字

ecotone ； deciduous forest ； evergreen broad-leaved forest ； depth of edge influence ； Nansi forest dynamic plot

國際替代計量

Vegetation Composition and Structure in the Ecotone between Deciduous and Evergreen Broad-leaved Forests in an Upstream Region of Nantzuhsiensi, South-Central Taiwan

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