Table 7. Rates of change (and P values) in power to detect -3% per year trends in species’ abundance and -1% per year trends in community metrics over 20 years, for four sample effort parameters. Rates of change for each species/community metric were calculated by taking partial derivatives of the power model and solving using average effort levels of designs achieving between 80% and 90% power for each species/community metric. Species and community metric codes are as in Fig. 2.

Species
No. sites
No. sample years
No. point-count
stations
No. surveys
BCCH
0.0058  (0.000)
0.0133  (0.000)
0.0095  (0.000)
0.0237  (0.000)
BGNW
0.0114  (0.000)
0.0016  (0.000)
0.0169  (0.000)
0.0643  (0.000)
BHCO
0.0062  (0.000)
0.0100  (0.000)
0.0104  (0.000)
0.0296  (0.000)
GRJA
0.0054  (0.000)
0.0145  (0.000)
0.0046  (0.000)
-0.0003  (0.891)
PIWO
0.0052  (0.000)
0.0142  (0.000)
0.0068  (0.000)
0.0224  (0.000)
WBNU
0.0058  (0.000)
0.0137  (0.000)
0.0016  (0.000)
0.0026  (0.147)
YWAR
0.0156  (0.000)
0.0043  (0.000)
0.0053  (0.000)
0.0470  (0.000)
GN
0.0265  (0.000)
0.0075  (0.000)
0.0125  (0.000)
0.1431  (0.000)
 
Average
   0.0103
   0.0098
   0.0084
    0.0416