The most often used method is by measuring rainfall above the canopy and subtract throughfall and stem flow[1]).
However, the problem with this method is that the canopy is not homogeneous, which causes difficulty in obtaining representative throughfall data.
A method employed to avoid this problem is covering forest floor with plastic sheets and collecting the throughfall.
The method by Hancock and Crowther[5] avoided these problems by making use of the cantilever effect of branches.
[6] However, the disadvantages of these methods are that only information about one single branch is obtained and it would be quite laborious to measure an entire tree or forest.