应用全天空照片估计林分透光孔隙度(郁闭度)

林分结构通过影响林内环境与生物因子,决定森林生态系统服务功能发挥;同时,通过调整林分结构亦可达到森林合理经营的目标。林分透光孔隙度(郁闭度)是决定林分结构的重要因子之一,它可以用来表征光、水等环境因子通过林冠进入林内的再分布状况。因此,合理、精确地确定林分内的郁闭状况,无论在森林经营与管理,还是在森林生态精细研究中,都显得十分重要。本文在以往研究的基础上,详细介绍了应用全天空照片(Hemispherical photograph/whole sky photograph)确定林分内一定高度(通常为1 m)的林分郁闭度或林分透光孔隙度(两者互补)的方法与步骤,重点讨论了在应用全天空照片确定林分郁闭度/透光孔隙度时选择的有效范围和应注意的实际问题。

Estimation on optical porosity or canopy closure for a forest stand with hemispherical images

Forest structure can not only influence the inhabited and biological factors in stands,but also determine the ecological functions of forest ecosystems.With the help of adjusting stand structure,reasonable forest management can come true.As one of the important indexes of forest structure,stand light transmission porosity or canopy closure can reflect the redistribution of light,water and other environmental factors entered the stand through forest canopy.It also plays a vital role on both forest management and many fine studies on forest ecology.Therefore,it is necessary to find a reasonable and accurate method to measure the light transmission porosity or canopy closure of a stand.This paper gave a detailed introduction on how to use hemispherical photograph to estimate canopy closure on the basis of the former related studies,and discussed in detail the selection of effective area of hemispherical photography,and some problems we have to pay attention to.