Table 3.

Climate change causal associations. Regression coefficients and test statistics for linear mixed models examining changes in three community attributes and their association with changes in annual temperature after controlling for survey effort for 404 North American CBC circles from 1975 to 2001 containing a total of 227 species. The mixed models are based on a longitudinal study design with year representing the temporal component. The models include longitudinal effects for temperature (T) and survey effort (E) and cross-sectional effects for temperature (T1975) and survey effort (E1975). Coefficients with p ≤ 0.05 are shown in bold.

coefficients.e.tp-value
species richness
 intercept−12.18982.0709−5.890.0000
 year0.04090.01083.780.0002
T0.34590.04867.120.0000
T19752.27120.080528.230.0000
E5.46520.129542.200.0000
E19758.67420.513716.890.0000
body mass
 intercept1.88700.0159118.830.0000
 year0.00030.00013.820.0001
T0.00230.00064.050.0001
T1975−0.00930.0006−15.220.0000
E−0.00310.0014−2.170.0301
E1975−0.01650.0039−4.220.0000
occupancy
 intercept340.150312.022228.290.0000
 year0.36820.025014.710.0000
T−0.09720.1419−0.680.4934
T1975−3.90390.4675−8.350.0000
E−9.27660.3720−24.930.0000
E1975−8.39262.9822−2.810.0051