臺灣中部常綠闊葉林小尺度植物種類豐富度的決定因子

DETERMINANTS OF FINE-SCALE PLANT SPECIES RICHNESS IN AN EVERGREEN BROAD-LEAVED FOREST IN CENTRAL TAIWAN

胡元瑋(Yuan-Wei Hu) ； 郭礎嘉(Chu-Chia Kuo) ； 曾喜育(Hsy-Yu Tseng) ； 曾彥學(Yen-Hsueh Tseng)

《中華林學季刊》 50卷3期 (2017/09) Pp. 279-308

摘要

為瞭解森林小尺度植物種類豐富度(SR)的決定因子，於臺灣中部北東眼山常綠闊葉林設置1 ha內容100個100 m^2的連續樣區，測定地表高程、光度、土壤有機質(OM)、土壤pH值、土壤總碳量(TC)、土壤總氮量(TN)、樹木胸高斷面積(BA)和植物SR(喬木、灌木和草本)。以皮爾森相關係數評定各環境因子之相關性，以路徑分析測試環境變數對植物種類豐富度的影響，以典型對應分析檢視植物種類分布與環境梯度間的相關性。在正相關係數中，以土壤性質間的相關性最高，其次為喬木SR與灌木SR、草本SR與高程；負相關係數中，以土壤pH值與土壤性質間的相關性最高，其次為喬木SR與土壤pH值、草本SR與光合作用光子通量密度(PPFD)。路徑分析可解釋11.2-28.5%的環境變量對植物種類變異，層級模式為︰喬木SR影響灌木SR、喬木BA影響灌木SR，植物SR和喬木BA之間的關係並不顯著。典型對應分析可解釋6.1-14.0%的環境變異，以高程和光度的相關係數較大，但整體來說樣區內的環境條件差異不大且物種組成相近，無法用單一因子來解釋其變異。有幾個可能的影響因子在此並未考慮，像是種子散播、種間的交互作用、小尺度的干擾、資源及非生物條件的異質性、動物和微生物的作用等。

關鍵字

典型對應分析 ； 常綠闊葉林 ； 路徑分析 ； 光合作用光子通量密度 ； 種類豐富度 ； 土壤肥力

並列摘要

In order to understand the determinants of fine-scale plant species richness (SR) in forest, elevation, irradiance, soil organic matter (OM), soil pH, soil total carbon (TC), soil total nitrogen (TN), tree basal area (BA) and plant SR (trees, shrubs, and herbs) were determined in 1 ha containing 100 contiguous 100 m^2 quadrats in an evergreen broad-leaved forest in Peitungyen mountain of central Taiwan. The correlations among environmental factors were assessed using Pearson coefficient of correlation. The effects of environmental factors to plant SR were tested using path analyses. The correlations between plant species distribution and environmental gradient were inspected using canonical correspondence analysis (CCA). The positive coefficients among soil properties are highest, and then are the ones between tree SR and shrub SR, herb SR and elevation. The negative coefficients between soil pH and soil properties are highest, and then are the ones between tree SR and soil pH, herb SR and photosynthetic photon flux density (PPFD). The path analyses explained 11.2-28.5% of the variance for environmental factors to plant SR. The hierarchical model is soil tree SR affects shrub SR, tree BA affects shrub SR. The correlation between plant SR and tree BA is not significant. CCA explained 6.1-14.0% of the variance in environment. The coefficient of elevation and irradiance is higher than others. As a whole, the environment factors and species composition are similar and couldn't be explained by single factor. Several factors not considered here might affect fine-scale species richness, such as seed dispersal, interspecific interactions, fine-scale disturbances, heterogeneity in resources and abiotic conditions and the effects of animals and microorganisms, etc.

並列關鍵字

Canonical correspondence analysis ； Evergreen broad-leaved forest ； Path analysis ； Photosynthetic photon flux density ； Species richness ； Soil fertility