Table 2.
Multiple stepwise regression models of the relationship between vertical structural complexity and environmental variables for five vegetation types on the Tibetan Plateau
| Height-maxa | Height-var | Height-even | |||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Forest | Pc | VIFb | R2 | P | VIF | R2 | P | VIF | R2 | ||||||
| AI | ˂0.001 | 1.136 | 0.352 | 0.43 | AI | ˂0.001 | 1.347 | 0.398 | 0.589 | AI | ˂0.001 | 1.221 | 0.104 | 0.229 | |
| Wind | 0.003 | 2.546 | 0.051 | MAT | ˂0.001 | 4.972 | 0.099 | UR | ˂0.001 | 1.107 | 0.032 | ||||
| MAT | 0.057 | 2.713 | 0.027 | pH | 0.117 | 1.28 | 0.021 | Tdiurnal | 0.114 | 1.329 | 0.019 | ||||
| UR | 0.037 | 1.4 | 0.012 | Wind | ˂0.001 | 1.316 | 0.074 | ||||||||
| PO2 | 0.002 | 5.343 | 0.059 | ||||||||||||
| Shrublands | P | VIF | R2 | P | VIF | R2 | P | VIF | R2 | ||||||
| AI | 0.001 | 2.874 | 0.603 | 0.861 | AI | 0.025 | 1.987 | 0.403 | 0.538 | AI | 0.001 | 1.726 | 0.669 | 0.854 | |
| Wind | 0.012 | 2.234 | 0.18 | Wind | 0.083 | 1.987 | 0.135 | Tdiurnal | 0.012 | 1.46 | 0.151 | ||||
| pH | 0.204 | 2.792 | 0.078 | SOC | 0.235 | 1.224 | 0.034 | ||||||||
| Alpine meadow | P | VIF | R2 | P | VIF | R2 | P | VIF | R2 | ||||||
| PO2 | ˂0.001 | 1.86 | 0.151 | 0.408 | MAT | ˂0.001 | 3.445 | 0.350 | 0.664 | Wind | ˂0.001 | 1.06 | 0.11 | 0.127 | |
| Wind | ˂0.001 | 4.133 | 0.110 | Wind | ˂0.001 | 4.122 | 0.231 | SOC | 0.098 | 13.03 | 0.007 | ||||
| Tdiurnal | ˂0.001 | 1.296 | 0.074 | PO2 | ˂0.001 | 1.858 | 0.065 | TN | 0.102 | 13.164 | 0.006 | ||||
| MAT | 0.115 | 3.495 | 0.049 | AI | 0.06 | 1.81 | 0.018 | pH | 0.161 | 1.114 | 0.004 | ||||
| AI | 0.095 | 2.221 | 0.018 | ||||||||||||
| pH | 0.074 | 1.107 | 0.007 | ||||||||||||
| Alpine steppe | P | VIF | R2 | P | VIF | R2 | P | VIF | R2 | ||||||
| Tdiurnal | ˂0.001 | 1.163 | 0.39 | 0.477 | MAT | ˂0.001 | 2.536 | 0.233 | 0.506 | TN | ˂0.001 | 1.171 | 0.083 | 0.194 | |
| AI | 0.124 | 1.229 | 0.058 | Wind | ˂0.001 | 3.629 | 0.186 | MAT | ˂0.001 | 1.005 | 0.071 | ||||
| Wind | ˂0.001 | 1.163 | 0.029 | PO2 | ˂0.001 | 2.074 | 0.044 | UR | 0.032 | 1.166 | 0.04 | ||||
| AI | 0.008 | 1.269 | 0.023 | ||||||||||||
| SOC | 0.037 | 1.175 | 0.019 | ||||||||||||
| Alpine desert grasslands | P | VIF | R2 | P | VIF | R2 | P | VIF | R2 | ||||||
| Tdiurnal | ˂0.001 | 1.362 | 0.205 | 0.33 | Wind | ˂0.001 | 1.893 | 0.174 | 0.445 | Wind | 0.058 | - | - | 0.046 | |
| Wind | 0.008 | 1.168 | 0.111 | UR | ˂0.001 | 1.534 | 0.151 | ||||||||
| AI | 0.135 | 1.288 | 0.015 | Tdiurnal | 0.007 | 1.562 | 0.091 | ||||||||
| MAT | 0.079 | 2.175 | 0.029 | ||||||||||||
aHeight-max, maximum plant height within a plot; Height-var, coefficient of variation of plant height; Height-even, Shannon evenness of plant height.
bVIF variance inflation factor, MAT annual mean temperature, AI aridity index, Wind wind speed, PO2 atmospheric oxygen partial pressure, UR ultraviolet radiation, Tdiurnal diurnal temperature range, SOC soil organic carbon, TN soil total nitrogen content.
cAll models were significant at p < 0.001. R2 for each model and its independent variables are provided separately.