Hello Shailender, you can find most of the protocols in "New handbook for standardised measurement of plant functional traits worldwide" by Pérez-Harguindeguy et al. 2013. Australian Journal of Botany 61, 167–234.
In my lab we have also used a photographic method where we quantified the amount of canopy vs open sky as viewed from digital images taken viewing upwards along the stream thalweg.