Table 2 The effect of environmental variables on bird diversity components at patch characteristics and isolation metrics.
Explanatory variables | Response variables | |||||
|---|---|---|---|---|---|---|
Species richness of all birds | Functional diversity of all birds | Phylogenetic diversity of all birds | Species richness of forest bird specialists | Functional diversity of forest bird specialists | Phylogenetic diversity of forest bird specialists | |
GAM estimates of function slopes with standard errors (in brackets) for explanatory variables with assumed linear response | ||||||
Intercept | 19.06994 (2.051163)*** | 0.00596 (0.00085)*** | 63.23644 (3.35101)*** | 11.92428 (1.44099)*** | 0.07706 (0.01098)*** | 47.20254 (3.04480)*** |
Forest age | 0.09464 (0.01640)*** | 0.00001 (0.00001) ’ | − 0.09458 (0.02574) *** | 0.06845 (0.01137) *** | 0.00002 (0.00009) | − 0.01585 (0.02487) |
Stand density | 0.00084 (0.02351) | 0.00002 (0.00001)* | 0.00534 (0.03829) | 0.02145 (0.01646) | 0.00007 (0.00012) | − 0.01375 (0.03414) |
Explanatory variables included as splines to control for potential non-linearity, with degrees of freedom presented | ||||||
NND | Df = 1.000’ | Df = 1.000 | Df = 1.000 | Df = 3.033 | Df = 1.000 | Df = 1.000 |
PROX | Df = 2.986* | Df = 1.000’ | Df = 1.000** | Df = 3.073* | Df = 1.000 | Df = 1.000 |
Forest area | Df = 2.908*** | Df = 1.000 | Df = 1.801** | Df = 3.225*** | Df = 1.903 | Df = 1.000*** |
Number of species | Not included | Df = 1.845*** | Not included | Not included | Df = 1.000*** | Not included |
Coniferous species | Df = 1.496* | Df = 1.027 | Df = 1.000 | Df = 1.000*** | Df = 2.552** | Df = 1.003 |
Share of dominant species | Df = 1.000* | Df = 2.401 | Df = 1.000 | Df = 1.000* | Df = 2.021 | Df = 1.000 |
SI | Df = 1.000*** | Df = 1.000 | Df = 1.000 | Df = 1.000** | Df = 1.908* | Df = 1.000 |
