林火對於東卯山區台灣二葉松林地土壤冲蝕量及養分流失量之影響

EFFECTS OF FIRE ON THE SOIL EROSION AND NUTRIENT LOSS OF TAIWAN RED PINE FOREST AT MT. TONG-MAO

10.29417/JCSWC.198611_17(2).0005

林昭遠(Chao-Yuan Lin)；陳明義(Ming-Yih Chen)；呂金誠(King-Cherng Lu)

中華水土保持學報

17卷2期（1986 / 11 / 01）

42 - 49

繁體中文

本試驗係以東卯山區台灣二葉松林之火燒個案，藉土壤、水質及植物體之觀測與分析來探討林火對於台灣二葉松林地土壤冲蝕量及養分流失量之影響。初步結果摘要如下：1.火燒區土壤除了有機質含量降低外，pH值、有效性磷及交換性鉀、鈉、鈣、鎂之含量均提高，以有效性磷增加之幅度尤大。2.火燒區之地表逕流量大於對照區。經過約九個月之觀測，火燒區地表冲蝕深度平均爲1.67 cm。3.逕流水之pH值，火燒區小於對照區。火燒區與對照區逕流水之含磷量皆甚低，檢定不出其濃度，惟由火燒區地表冲失之土壤，其有效性磷含量平均爲39.4 ppm，故磷之流失主要係土壤冲蝕所致。4.觀測初期，鉀之流失，火燒區大於對照區，其流失主要是逕流水之淋洗及土壤冲蝕所致。5.火燒區鈣之流失與磷類似，大部份係隨土壤冲蝕而流失，其經由逕流水淋失之量，火燒區遠低於對照區。6.鈉與鎂經由逕流水之流失量，火燒區大於對照區。火燒區冲蝕土壤之交換性陽離子含量中，鈉與鎂之含量皆低於鈣。7.試區現地觀測結果，台灣二葉松新鮮落葉層之水分含量爲53.1%，半腐化層爲177.2%，而火燒區灰分爲54.5%。故火燒會降低林地之保水能力。8.火燒後林地有機質層營養元素之損失以氮素之31.86 g / m^2爲最大，損失率達58.7%。

Taiwan red pine forest at Mt. Tong Mao was burned in November of 1984. Soil characteristics, surface runoff and litter layer of burned and unburned plots were investigated and analyzed so as to unfold the post-fire soil erosion and nutrient loss. Preliminary results obtained were summarized as follows: 1. At the burned area, soil pH, exchangeable potassium, sodium, calcium, magnesium, and particularly available phosphorus, were all enhanced, but organic matter was reduced by burning. 2. Amount of surface runoff of the burned plot was higher than that of the unburned one. Erosion depth during the 9-month observation period was 1.67cm at the burned area. 3. Surface runoff of the burned plot showed lower pH than that of the unburned plot. Phospnorus concentrations of runoff from both plots were too low to be detected, but average content of available phosphorus in soil eroded from burned plot was 39.4ppm. It implies that most phosphorus loss was due to soil erosion. 4. Potassium loss was due to both runoff extracting and soil erosion at the burned plot. 5. Calcium, behaved similarly with phosphorus, was lost through soil erosion at the burned plot. Compared with the unburned area, calcium lost with surface runoff was lower in the burned area. 6. Sodium and magnesium losses through runoff at the burned area were greater than those at the check. Both exchangeable sodium and magnesium contents in soil eroded from burned plot were much lower than that of calcium. 7. Measuring the litter sampled from the site, moisture content was 53.1% in fresh litter, 177.2% in semi-decomposed litter, and 54.5% in ashes. It showed that burning could reduce the water storage capacity of surface organic matter. 8. Among the nutrients in organic litter, nitrogen lost the most (31.86g/m^2) following burning.