苗栗海岸地區不同齡級木麻黃防風林生長之調查

Investigation on the Growth of Casuarina Windbreaks of Different Age Classes in Miao-Li Coastal Area

陳財輝(Tsair-Fuei Chen) ； 呂錦明(Chin-Ming Lü) ； 沈慈安(Tse-An Shen)

《林業試驗所研究報告季刊》 5卷1期 (1990/03) Pp. 17-24

https://doi.org/10.7075/BTFRI.199003.0017

摘要

對栽植於苗栗縣後龍鎮海濱之不同齡級木麻黃防風林，實施樣區調查，並設置枝葉收集網，調查各齡級木麻黃林分葉景（接合小枝）之季節性變動，以及從竹南氣象站，收集近年來本地區之降雨量。調查結果顯示，各齡級木麻黃林分密度，每公頃從400株到7,500株左右，不同林齡間有極大之變化，幼齡林分之幹部分叉現象嚴重，由於林冠之競爭激烈，導致幼齡木之生長不良，而老齡林分則又過於疏開，難以收到良好的海岸防風效果。試驗林分之形狀比為48-113，13年生以下林分皆在100以上，而17年生以上林分則低於70，顯示老齡林分之抗風能力較強。試區林分之地被植物，亦隨著木麻黃林分之生長而異，幼齡林之地被植物數量較少，壯齡林則以纏繞植物及馬纓丹為較多，而且纏繞植物會影響林木的生長，老齡林之地被則以陽性植物之馬纓丹為優勢種。木麻黃林分落枝葉量的最高峰在10-11月間，受東北季風之影響極大，而林分最多葉量生產則可能在8、9月間。本地區之降雨量，主要分布在2-8月間，歷年來之月份降雨量變化極大，對海岸造林極為不利，而9月~翌年1月間之雨量極少，現存海岸林分深受東北季風帶來高濃度鹽沬的危害，嚴重影響林木之生長。

關鍵字

木麻黃 ； 防風林 ； 生長

並列摘要

Sampling plots were set to investigate the growth parameters of uneven-aged casuarina (Casuarina spp.) plantation on she seashore of Miao-Li county, litter trap were also set to study the seasonal leaffall variation, precipitation data were collected from Tsu-Nan weather station.
The results showed that, the stand density of different age-classes varied from 400 to 7,500 trees per hectarc, young stand crotched severely; growth of the young trees performed very badly by crown competition, and stand density of old stands were too low to provide sufficient protection. The shape ratio (tree height/DBH) of the sampling plots were 48 to 113 in which stands under 13-year-old of age have a higher shape ratio (above 100), and old stands (over 17-year-old) have a lower ratio of under 70, this means that the old stands have better wind resistant ability.
The ground vegetation varied with the growth of the casuarina stands, very few in young stands, and more in elder stand. Vigorous growth of twiner plants and common lantana (Lantana comara) affect tree growth severely. In the old stands, the common lantana were the dominant species.
Maximum leafall of casuriana stands were between October to November, it was influenced by the north-eastern monsoon, and the maximum leaves production were in August and September. Most of the rain fall were in February to August, variation of the month rain fall were very high within the last six years, it makes the reforestation practices very difficult. Rain fall were very low from September to January of next year, and the trees of the windbreaks sufferd from salt sputter brought by strong north-eastern monsoon, it reduces growth of the trees severely.

並列關鍵字

Casuarina ； Windbreaks ； Growth