My field sample plots are 30x30m square and I have to measure canopy coverage along with other field data. Ho can I use GRS densiometer or Spherical densiometer to measure the canopy coverage of my sample plot with less error of estimation.
Hello Hasan,
Based on my field experience in using the spherical densiometer (SD) the only way to get around the subjectivity is to get more experience it by comparing the results you get to a colleagues own (who measured the same area around the same time of day).
I think the SD is only good for characterizing a canopy as either open, gap or closed. For better more objective results I recommend (and have done myself) switching to using a fish-eye lenses mounted to a standard point and shoot camera (DSLR cameras would be better but the point and shoot would get the job done). You should do this once you have access to one. Remember also if you are making the switch, pictures should always be taken when the sun is highest in sky.
Hope this helps.
Hi Hasan,
To use the Densiometer, you must to take four measures in the same point with the densiometer turned to north, south, west and east. These four measures will reduce the error in your canopy cover estimate.
In my studies in savanna ecoystems, I use the metodology described by Engelbrecht & Hertz (2001), using a common camera of 35 mm and the photoshop. I think this metodology is enough accureted, and a good option if you don´t have access to a fish-eye lent.
ENGELBRECHT, B.M.J., AND H.M. HERZ, 2001. Evaluation of different methods to estimate understorey light conditions in tropical forests. J. Trop. Ecol. 17: p.207–224.
Best regards,
Alan
Spherical densiometer (SD) may be the helpful equipment for canopy coverage.
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