Appendix C. The effects of diameter, soil depth and number of days until a white root turned brown (pigmentation) on the risk of fine root mortality calculated using Cox proportional hazard regression.
TABLE C1. The effects of diameter, soil depth, and number of days until a white root turned brown (pigmentation) on the risk of fine root mortality calculated using Cox proportional hazard regression. The value of the hazard ratio (HR) is less than one when the parameter estimate (β) is negative. This indicates an inverse relationship between the variable (e.g., diameter) and the risk of death. When the Chi-Square test is significant, then the description of the risk is indicated in the Risk column. SE is the standard error of the parameter estimate, β P is the level of significance for the χ2 test with degrees of freedom = 1.
β |
SE |
χ2 |
P |
HR |
Risk |
|
Diameter |
||||||
A. platanoides |
-1.85 |
1.38 |
1.79 |
0.181 |
0.157 |
--- |
A. pseudoplatanus |
-1.97 |
1.73 |
1.30 |
0.254 |
0.139 |
--- |
F. sylvatica |
-2.06 |
1.08 |
3.64 |
0.057 |
0.128 |
Thin>Coarse |
Q. robur |
-2.39 |
1.01 |
5.51 |
0.019 |
0.092 |
Thin>Coarse |
T. cordata |
-0.60 |
0.94 |
0.41 |
0.523 |
0.548 |
--- |
A. alba |
-6.73 |
2.16 |
9.69 |
0.002 |
0.001 |
Thin>Coarse |
L. decidua |
1.95 |
2.00 |
0.96 |
0.328 |
7.057 |
--- |
P. abies |
-2.57 |
1.25 |
4.22 |
0.040 |
0.076 |
Thin>Coarse |
P. nigra |
-0.75 |
0.88 |
0.73 |
0.393 |
0.470 |
--- |
P. sylvestris |
-0.41 |
1.24 |
0.11 |
0.742 |
0.665 |
--- |
P. menziesii |
-1.69 |
1.41 |
1.43 |
0.231 |
0.184 |
--- |
Soil Depth |
||||||
A. platanoides |
-0.03 |
0.01 |
27.73 |
<0.0001 |
0.969 |
Shallow>Deep |
A. pseudoplatanus |
-0.03 |
0.01 |
11.44 |
0.0007 |
0.975 |
Shallow>Deep |
F. sylvatica |
-0.01 |
0.01 |
4.74 |
0.0295 |
0.988 |
Shallow>Deep |
Q. robur |
-0.02 |
0.004 |
24.83 |
<0.0001 |
0.976 |
Shallow>Deep |
T. cordata |
-0.01 |
0.004 |
11.04 |
0.0009 |
0.986 |
Shallow>Deep |
A. alba |
0.01 |
0.01 |
0.93 |
0.335 |
1.01 |
--- |
L. decidua |
-0.01 |
0.01 |
2.51 |
0.113 |
0.985 |
--- |
P. abies |
-0.03 |
0.01 |
18.93 |
<0.0001 |
0.973 |
Shallow>Deep |
P. nigra |
-0.02 |
0.004 |
18.70 |
<0.0001 |
0.981 |
Shallow>Deep |
P. sylvestris |
-0.01 |
0.01 |
4.51 |
0.0336 |
0.989 |
Shallow>Deep |
P. menziesii |
-0.03 |
0.01 |
12.20 |
0.0005 |
0.972 |
Shallow>Deep |
Pigmentation |
||||||
A. platanoides |
-0.01 |
0.004 |
13.00 |
0.0003 |
0.987 |
Fast>Slow |
A. pseudoplatanus |
-0.01 |
0.002 |
4.18 |
0.041 |
0.995 |
Fast>Slow |
F. sylvatica |
-0.01 |
0.002 |
8.71 |
0.003 |
0.994 |
Fast>Slow |
Q. robur |
-0.003 |
0.001 |
11.22 |
0.001 |
0.997 |
Fast>Slow |
T. cordata |
0.001 |
0.002 |
0.59 |
0.444 |
1.001 |
--- |
A. alba |
-0.004 |
0.01 |
0.61 |
0.435 |
0.996 |
--- |
L. decidua |
-0.03 |
0.01 |
3.75 |
0.052 |
0.975 |
Fast>Slow |
P. abies |
-0.002 |
0.001 |
5.42 |
0.020 |
0.998 |
Fast>Slow |
P. nigra |
-0.01 |
0.002 |
11.02 |
0.001 |
0.994 |
Fast>Slow |
P. sylvestris |
-0.01 |
0.002 |
7.10 |
0.008 |
0.995 |
Fast>Slow |
P. menziesii |
-0.001 |
0.002 |
0.17 |
0.682 |
0.999 |
--- |
Example calculation with HR: in A. platanoides, for every day a root remained white, its risk of death in the next sampling interval decreased an estimated 1.3% (=100*(0.987-1)), holding diameter and depth in soil constant.