四湖海岸木麻黃林分降水、幹流水及穿落水之養分含量與輸入

Nutrient Contents and Inputs of Precipitation, Stemflow, and Throughfall in Shihu Coastal Casuarina Stands, Central Taiwan

陳財輝(Tsai-Huei Chen) ； 許博行(Bor-Hung Sheu) ； 張峻德(Chun-Te Chang)

《台灣林業科學》 14卷4期 (1999/12) Pp. 419-435

https://doi.org/10.7075/TJFS.199912.0419

摘要

本研究調查雲林縣四湖海岸2個3年生及1個9年生木麻黃人工林穿落水、幹流水、及林外雨等水溶液的養分輸入動態。四湖海岸地區依每月降水量可分成乾濕兩季，乾季之月平均降水量僅38.7mm，濕季則高達489mm。木麻黃林分內外降水的pH值，隨著降水量增加而降低，而且幹流水因淋洗較多樹體所堆積的氫離子，pH值明顯較穿落水低。降水之懸浮質及電導度，乾季為濕季的10-20倍左右，且乾季之幹流水及穿落水皆較林外雨高出5-16倍，在濕季亦高出4-11倍，顯示本地區木麻黃林內降水所淋洗的粉塵及其養分量極高。鈉、鉀、鈣、鎂、銨態氮及硝態氮、氯、硫酸根等陰陽離子之濃度，乾季皆較濕季高，而且由於乾季降水量較少且降水間隔較長，幹流水之離子濃度大致較穿落水高，但濕季則因降水較頻繁，反而以幹流水之離子濃度較低者為多。木麻黃林內降水的養分輸入量中，鈉及氯在9年生林分明顯較3年生林分高，此係9年生林木樹體高大、樹冠截留粉塵及鹽霧的面積較大所致。林內穿落水的養分輸入量，亦遠大於林外雨及幹流水量。四湖海岸木麻黃林內年間降水的養分輸入量，幹流水及穿落水合計之鉀、鈣、鎂及鈉量分別為27.7-39.9，25.2-49.4，20.9-40.9及125.4-231.5kg ha^(-1) yr^(-1)，銨態氮及硝酸態氮各為28.2-58.0，33.6-67.2kg ha^(-1) yr^(-1)，氯及硫酸根各為218.7-407.3，57.8-113.1kg ha^(-1) yr^(-1)，此種輸入可提供海岸砂地木麻黃生長的重要養分來源。

關鍵字

木麻黃 ； 海岸防風林 ； 降水 ； 養分量

並列摘要

Dynamic variations of nutrient inputs from stemflow and throughfall to 2 Casuarina stands aged 3 yr. and other stand aged 9 yr on the Shihu coast, Yunlin county were investigated. Dry and wet seasons were divided according to the monthly rainfall during June 1997 to May 1998. The dry season (October to May) average monthly rainfall was only 38.7mm, while that in the wet season (June to September) was 489mm. Acidity (pH) of stemflow and throughfall solutions decreased as total rainfall increased, with obviously lower pH values in stemflow solutions showing more H(superscript +) leaching. Suspended solids and conductivity of these 2 solutions in the dry season were about 10-20 times greater than those in the wet season. Moreover, these 2 values of the 2 solutions were 5 to 16 times in the dry season and 4 to 11 times in the wet season greater than those of rainfall collected outside of stands. Concentrations of ions like sodium, potassium, calcium, magnesium, ammonium or nitrate nitrogen, chloride, and sulphate acid were greater in the dry season than in the wet season. Ionic concentrations of stemflow in the dry season were greater than those of throughfall, but opposite results in the wet season were observed. Most ionic fluxes through the 2 aged stands during the study period were similar. Only sodium and chloride were significantly greater in the 9-yr-old stand than in the 3-yr-old stands, indicating more blown sea salt was adhering to the larger surface area of older trees, while other ions produced from both aged stands were not much different. Amounts of nutrient inputs from throughfall within a year were much greater than from either stemflow or rainfall outside of stands. The average inputs of different ions through precipitation from 3 stands were 128.4-231.5kg ha^(-1) yr^(-1) for sodium, 27.7-39.9kg for potassium, 25.2-49.4kg for calcium, 20.9-40.9kg for magnesium, 28.2-58.0kg for ammonium-nitrogen, 33.6-67.2kg for nitrate-nitrogen, 215.7-407.3kg for chloride, and 57.8-113.1kg ha^(-1) yr^(-1) for sulphate. These high nutrient inputs from precipitation are obviously important to Casuarina stands growing on coastal sandy soil.

並列關鍵字

Casuarina ； coastal windbreaks ； rainfall input ； nutrient content