At four sites in Idaho, frequency was measured separately with three different-sized plots (10 x 25, 15 x 33.5, and 20 x 50 cm) arranged in a nested configuration. These individual frequency values were added together to create a summed “frequency.” This summed value was compared to the original frequency values generated by each individual plot size in respect to its ability to detect range trend. The summation procedure consistently detected smaller changes in frequency than any individual plot size. In addition, the summed values detected a significant change in more species at each site. Summing the frequency values usually detected changes at a lower alpha level than did any single plot (0.10 vs. 0.20).
Smith, Stuart D.; Bunting, Stephen C.; and Hironaka, M.
"Evaluation of the improvement in sensitivity of nested frequency plots to vegetational change by summation,"
Great Basin Naturalist: Vol. 47
, Article 16.
Available at: http://scholarsarchive.byu.edu/gbn/vol47/iss2/16