中文摘要 了解植體中養分累積情形與土壤中養分的釋放可推估森林生態系中的養分循環,進而對森林經營與管理有更大的助益。七星山區的火山灰土壤性質與一般森林土壤不同,所孕育出來之優勢樹種生物量與養分含量亦值得探討。研究目的為於七星山南坡600-900公尺的海拔範圍,選取十二種優勢樹種生物量估算與元素濃度分佈之特性與表土0-5及5-15公分的土壤性質。 研究結果顯示,七星山地區土壤受到母質影響,造成土壤中有效性磷含量較低,表土5公分土壤的有效性養分明顯高於5-15公分土壤(p<0.05),而海拔高度的不同,也會使土壤之pH、有機碳、可礦化性氮與有效性氮、磷、鉀造成顯著差異(p<0.05)。十二種優勢樹種樹幹與全株生物量,除了樹杞與楊梅外,皆可以Biomass = a (DBH)b之迴歸式來估算,若以本研究區DBH<30公分的十二種優勢樹種來看,可以分別以Y=0.0283 X2.2377與Y=0.0495 X2.0578來加以估算樹幹與全株的生物量。 本研究區優勢樹種的葉片養分濃度大小為N>K>Ca>Mg>P,在樹枝與樹幹則是K>N>Ca>Mg>P。相思樹在植體中可累積大量的氮,樹杞可累積大量的鈣與鎂,江某在葉片可累積鋅,在樹枝可累積鉀,而小花鼠刺的樹葉與樹幹則累積了銅。此四種樹種在本區優勢樹種中皆稱為蓄積型樹種。生態系的養分循環包含輸入、輸出與植物族群對環境間的交互作用。若能補充更多的資料,即可架構出完整的七星山區生態系養分循環。
Abstract It is helpful for us to manage the sustainable forestry if we can understand the nutrient accumulation in the ecosystem of vegetation species and nutrient release from the soil system. The forest soils in Chihsingshan Mountain are characterized by special andic soil properties of volcanic soils and nutrient distribution of dominant tree species, which are quite different with other forest soils in Taiwan. The study site is located in the south slope of Chihsingshan Mountain ranging from 600 to 900 m elevation. The objectives of this study are (1) to establish the biomass regression model and their validation and nutrient contents of twelve dominant tree species, and (2) to study the soil characteristics of surface (0-5 cm) and subsurface (5-15 cm) soil collected in this study area. The result indicated that the available phosphorus was low because of character of parent material, and the contents of soil available nutrients in surface soil (0-5 cm depth) are significantly higher than that in subsurface soil (5-15cm depth) (p <0.05). The elevation can significantly affect the soil properties of soil pH, organic carbon, mineralizable nitrogen, and available N, P, and K (p <0.05). The prediction of trunk and total biomass of dominant species can be estimated by the simulation model, biomass=a (diameter of breast height, DBH)b, except Ardisia sieboldii and Myrica rubra (p<0.05). We also can estimate the trunk and total biomass of all dominant tree species, which DBH is smaller than 30 cm in the study site, calculated by the regression models Y= 0.0283 X2.2377 and Y= 0.0495 X2.0578 (p <0.05). Furthermore, the order of the major nutrient concentrations in the leaf of dominant tree species was N>K>Ca>Mg>P, but the order of the major nutrient concentrations in the branch and trunk of dominant tree species was K>N>Ca>Mg>P. Much higher nutrient accumulators were found in different tree species and listed as followings: N in Acacia confusa, Ca and Mg in Ardisia sieboldii, Zn in the leaves and K in the branch of Schefflera octophylla, and Cu in the leaves and trunk of Itea parviflora. These four special tree species found in Chihsingshan Mountain were regarded as nutrient accumulator species in the dominant tree species in the study area. Nutrient cycling in an ecosystem includes both inputs and outputs of nutrients and involves the interaction of the plant community with its environment. If we can provide more valuable data, then we can establish the whole nutrient cycling model for the forest ecosystem in Chihsingshan Mountain of northern Taiwan.