【摘要】 <正> 1953年日本学者门司正三等人提出,植物群体中直射光的垂直分布基本上接近于一般指数衰减规律:τ=e^-KL式中τ为群体内观测高度上的直射光穿透率（简称透光率）,K为消光系数,L为相应的累积叶面积指数。我们称（1）式为门司公式。门司以及后来的学者曾用不同的方法从理论上证明了这一公式,但他们的推导必须建立在一个前提下,即群体中叶面积的散布完全服从卜松分布律。那么,为什么必须具备这样更多还原

【Abstract】 The theoretical proof of Monsi formula must suppose that the distribution of leaf area in a standis exactly obeyed on Poission distribution law.Using methematical methods,this paper showsthe biological meanings of parameters in Poission distribution.It is indicated that Monsi formulais a special form of Poission distribution.And hence,the promise of Monsi formula has to bethat plant stand possesses a property of spatial Poission distribution.Most of the stand in thenature doesn’t possess this property,so the theoretical value doesn’t meet the measured value ofsolar direct radiation,which shows a definite deviation.The quantity of this deviation maybepossess some significations for studying thermal and dynamic states in plant stand.更多还原