Table 3.
Boosted regression tree results by perennial stream assessment region for O/E and O/E50. The variables shown are those included in the final model with their relative importance shown in parentheses. The ΔAIC value represents the difference in AIC between the model shown and the next best model
| Response variable | R 2 | ΔAIC | Variables in order of influence (left to right) | ||||||
|---|---|---|---|---|---|---|---|---|---|
| Statewide (n = 1386) | |||||||||
| O/E | 0.50 | 27 | AgUrb21_1km (56) | CondQrm (15) | SLOPE (11) | PPT (9) | Temp (9) | ||
| O/E50 | 0.57 | 85 | AgUrb21_1km (45) | SLOPE (19) | PPT (14) | CondQrm (12) | Temp (10) | ||
| Coastal group | |||||||||
| Coastal Chaparral (n = 216) | |||||||||
| O/E | 0.77 | 10 | Pop_5km (31) | PPT (15) | Ag_WS (14) | CondQrm (13) | Elevation (12) | MgO (9) | MinesDens_WS (6) |
| O/E50 | 0.84 | 48 | Pop_5km (33) | PPT (18) | Ag_WS (16) | CondQrm (12) | Elevation (11) | MgO (10) | |
| North Coast (n = 197) | |||||||||
| O/E | 0.63 | 34 | AgUrb21_WS (21) | Elevation (19) | Ngeo (19) | SLOPE (14) | MAFLOWU (14) | PPT (13) | |
| O/E50 | 0.76 | 24 | AgUrb21_WS (30) | SLOPE (25) | MAFLOWU (18) | Ngeo (17) | PPT (10) | ||
| South Coast (n = 385) | |||||||||
| O/E | 0.68 | 83 | UrBAN_1km (45) | MAFLOWU (16) | SLOPE (14) | CondQrm (13) | Temp (12) | ||
| O/E50 | 0.59 | 21 | UrBAN_1km (35) | SLOPE (16) | Ngeo (14) | Temp (13) | CondQrm (12) | MAFLOWU (10) | |
| Mountain group | |||||||||
| Lahontan (n = 200) | |||||||||
| O/E | 0.65 | 6 | SLOPE (33) | PPT (20) | MAFLOWU (16) | IMPERVMEAN_WS (16) | Temp (15) | ||
| O/E50 | 0.75 | 9 | SLOPE (27) | PPT (26) | Temp (21) | IMPERVMEAN_WS (14) | MAFLOWU (12) | ||
| Sierras (n = 203) | |||||||||
| O/E | 0.51 | 13 | SLOPE (36) | PPT (22) | Temp (20) | rDDENSC12_WS (12) | NewUrb_5km (10) | ||
| O/E50 | 0.60 | 30 | PPT (42) | SLOPE (24) | rDDENSC12_WS (12) | GrAZING_WS (12) | Temp (10) | ||
| Miscellaneous group | |||||||||
| Central Valley (n = 54) | |||||||||
| O/E | 0.64 | 4 | CondQrm (64) | SLOPE (25) | AgUrb21_1km (6) | Temp (5) | |||
| O/E50 | 0.44 | 4 | CaO (26) | SLOPE (24) | Temp (22) | CondQrm (14) | PctSed_ws (7) | Ag_WS (7) | |
| Interior Chaparral (n = 75) | |||||||||
| O/E | 0.65 | 26 | SLOPE (35) | CondQrm (29) | IMPERVMEAN_WS (27) | Ag_WS (9) | |||
| O/E50 | 0.71 | 5 | PPT (39) | CondQrm (35) | IMPERVMEAN_1km (26) | ||||
| Modoc (n = 56) | |||||||||
| O/E | 0.64 | 7 | CondQrm (26) | Ag_WS (21) | Temp (20) | IMPERVMEAN_WS (18) | SLOPE (15) | ||
| O/E50 | 0.66 | 3 | CondQrm (29) | IMPERVMEAN_WS (26) | Ag_WS (23) | Temp (22) | |||