落叶松人工林开阔度的主要环境效应

Effect of major environment of canopy openness produced by thinning in larch plantation

在2004年秋季,用全天照片法测定了辽东山区落叶松人工林4个不同间伐强度的开阔度,并用温湿度自动监测仪观测了4种开阔度不同高度和林外1m处的温度和相对湿度。结果表明:(1)林内外温湿度具有明显的日变化特征,林外的温湿度日变化均比林内大;(2)开阔度小的林分温度随高度的降低而减少,开阔度大的林分则呈脉动性变化,4种不同开阔度的相对湿度均自高向低逐渐增加;(3)开阔度小的林分温度最大值出现在14m,开阔度大的温度最大值出现在1m,林内相对湿度的最大值和最小值均出现在14m。

In the autumn of 2004, four canopy openness produced by different thinning intensities were estimated by the method using hemispherical photographic silhouette in a larch plantation in eastern Liaoning province. HOBO data loggers were applied to automatically measuring the temperature and relative humidity at four heights in vertical direction in the stands with different canopy openness. The four heights were set as middle of crown （14m above the ground）, near crown （10m）, middle stem （6m） and near ground （1m）. The results were as follows： （1） The characteristic of daily change of temperature and relative humidity of outer and within forest were obvious, and the change was bigger within forest than outer forest. （2） The change of vertical temperature and relative humidity were relative with the size of canopy openness, i.e., the temperature would reduce with height increasing in the smaller canopy openness （plot a and b）, and in bigger canopy openness （plot c and d）, their temperature would fluctuate. Relative humidity would increase with reducion of tree height whether smaller or bigger canopy openness. （3） In the smaller canopy openness, the biggest value of temperature appeared in the 14 m, however, in bigger canopy openness, the biggest value of temperature appeared in 1 m. In all canopy openness, the biggest and the smallest value of relative humidity appeared in the 14m.