Table 3.
Mean values of root tensile strength and root diameter, a and b values and adjusted r2 values of the power law eqn (1), expressing the decrease in tensile strength with increasing root diameter of the 13 analysed species in the order of their a value
| Species | Mean tensile strength (N mm−2) | Mean root diameter (mm) | a | b | n | Adjusted r2 |
|---|---|---|---|---|---|---|
| Geum reptans | 7·68 (0·29) | 0·90 (0·06) | 7·00 | –0·31 | 41 | 0·32*** |
| Luzula spicata | 30·25 (2·32) | 0·16 (0·01) | 5·91 | –0·78 | 35 | 0·43*** |
| Trifolium badium | 7·62 (0·52) | 0·78 (0·06) | 5·68 | –0·60 | 41 | 0·60*** |
| Luzula alpinopilosa | 18·52 (4·03) | 0·37 (0·04) | 5·44 | –0·93 | 17 | 0·57*** |
| Salix herbacea | 6·10 (0·41) | 0·92 (0·07) | 5·39 | –0·24 | 35 | NS |
| Poa alpina | 27·91 (3·88) | 0·30 (0·03) | 4·92 | –1·17 | 21 | 0·72*** |
| Campanula scheuchzeri | 3·78 (1·24) | 2·08 (0·25) | 3·98 | –0·36 | 6 | NS |
| Leucanthemopsis alpina | 4·26 (0·25) | 0·83 (0·03) | 3·81 | –0·26 | 31 | NS |
| Ranunculus glacialis | 2·74 (0·16) | 1·53 (0·08) | 2·93 | –0·33 | 30 | 0·09* |
| Veronica alpina | 6·76 (0·90) | 0·41 (0·02) | 2·92 | –0·71 | 40 | 0·26*** |
| Trisetum spicatum | 27·49 (2·47) | 0·24 (0·02) | 2·61 | –1·38 | 50 | 0·79*** |
| Arabis caerulea | 2·01 (0·20) | 2·50 (0·23) | 2·42 | –0·28 | 11 | NS |
| Salix breviserrata | NA | NA | NA | NA | NA | NA |
n is the number of roots tested. Values are means with s.e.m. in parentheses. ***P < 0·001, **P < 0·01, *P < 0·05; NS, not significant; NA, not available.