福山天然闊葉林25公頃永久樣區土壤性質之空間變異

Abstract

土壤之地形與植被因子直接作用於土壤，對土壤生成化育的影響很大。在不同的地形位置所形成的土壤之性質不盡相同，因而化育出不同的植被型態，而樹種的分佈差異對於土壤鹽基含量與養份的補充亦有不同。台灣東北部福山地區設置25公頃天然闊葉林永久樣區之目的之一，在於提供一個可供長期亞熱帶森林動態學研究的大型樣區。本研究的目的在於建立福山天然闊葉林永久樣區基本的土壤資料庫，以探討研究區內土壤性質分布及其變動與地形位置或植群分佈的關係，並試圖說明土壤養分狀況與植群分布間的關聯。 研究樣區分為80個土壤採樣網格區，採樣時將每個網格區分為四個相同分區，以土鑽在不同的深度0-5 cm、5-15 cm、15-30 cm進行採樣，並將四分區採集的土壤再混合成採樣網格區之代表性土壤樣品。再依五個不同的地形位置，包括平坦區、山頂區、斜坡區、溪流區及西北方山谷區域，對採樣網格進行數據分組及各種土壤性質之數據統計分析比對，檢視不同地形位置及植群分佈下土壤性質之差異及空間變化。 研究結果顯示，在不同的地形位置(平坦區、山頂區、斜坡區、溪流區及山谷區)其土壤的性質間有顯著差異(p<0.05)。地表5 cm的土壤有機碳含量與其他土壤性質具有顯著相關(p<0.05)，指出福山森林表層土壤性質深受土壤有機質含量之影響。有機碳有累積於地勢較低漥的地區的趨勢。此外，植被生育地類型的有機碳含量則顯著高於其他類型。根據地形因子與有機質的相關分析，顯示有機質可能亦受到植被的影響。有效磷與有效鉀含量在西北山谷區顯著較高(p<0.05)。樣區的三種森林生育地類型之分布與樣區不同的地形位置確實有關，顯示林相的分布與地形位置或土壤性質有關，應可進ㄧ步探討分析。

Both landscape and vegetation directly affect the soil formation and soil characteristics. The soils derived from different landscape positions and vegetation types are not exactly resemble on soil physical and chemical characteristics. One of the purposes of establishing Fushan permanent research site is to understand the dynamics of subtropical forest ecosystem. The objective of this study is to examine the relations between the change of soil properties and dominant landscape positions or distribution of main vegetation types. The research site was divided into 80 subplots for sampling. A subplot was divided into 4 equal parts by auger to sample the soil samples at 0-5 cm, 5-15 cm, and 15-30 cm soil depth. The study area was also divided into five different landscape-based regions including Slightly flat region, Summit region, Slope region Creek region, and Northwestern valley, to compare the difference of soil properties at different landscape regions or among different regions of vegetation types. The results of this study showed that there are significant differences of soil properties located at different landscape regions (p<0.05). The soil properties of surface 5cm depth are strongly related to it’s organic carbon content. The organic carbon content is higher in the lowland. Furthermore, the organic carbon content in vegetation Type1 is significantly higher than other vegetation Types. Pearson correlation coefficient between topographic factors and soil properties revealed that the organic carbon content could be related to the vegetation. Available P, available K are relative higher at the Northwestern valley region. The distribution of three vegetation types is related to the distribution of landscapes. Although the relations between soil properties and landscape have been better understood, further studies are required to clarify the relationships between soil nutrient status and the distribution of vegetation types in this permanent site.