Ecological Archives E096-047-A6
Katie E. Marshall and Jennifer L. Baltzer. 2015. Decreased competitive interaction drive a reverse species richness latitudinal gradient in subarctic forests. Ecology 96:461–470. http://dx.doi.org/10.1890/14-0717.1
Appendix F. Tables summarizing statistical results of regression of MFA dimensions with species richness and a summary of site characteristics that tend to be correlated with higher species richness.
Table F1. Linear regression statistics of multiple factor analysis dimensions predicting species richness. Dimensions with p values < 0.01 are bolded. Model R² = 0.51.
Coefficient |
Estimate (±SE) |
T value |
P value |
Intercept |
28.87 ± 0.66 |
43.82 |
< 0.001 |
Dimension 1 |
-1.24 ± 0.31 |
-3.96 |
< 0.001 |
Dimension 2 |
-2.48 ± 0.38 |
-6.57 |
< 0.001 |
Dimension 3 |
-1.83 ± 0.41 |
-4.43 |
< 0.001 |
Dimension 4 |
2.17 ± 0.47 |
4.65 |
< 0.001 |
Dimension 5 |
0.82 ± 0.52 |
1.58 |
0.116 |
Dimension 6 |
-1.90 ± 0.53 |
-1.69 |
0.094 |
Dimension 7 |
0.37 ± 0.56 |
0.67 |
0.504 |
Dimension 8 |
1.52 ± 0.59 |
2.56 |
0.011 |
Dimension 9 |
1.07 ± 0.63 |
1.71 |
0.091 |
Dimension 10 |
0.07 ± 0.65 |
0.10 |
0.918 |
Table F2. Site characteristics that tend to be correlated with high or low species richness in the Taiga Plains ecoregion.
Variable type |
Variable |
High species richness |
Low species richness |
Abiotic |
Current climate PC1 |
Colder temperatures |
Warmer temperatures |
|
Disturbance |
Low |
High |
|
Drainage |
Good drainage |
Poor drainage |
|
Frost table |
Absent |
Present |
|
Moisture class |
Mesic |
Hygric |
|
Organic soil thickness |
Thin organic layer |
Thick organic layer |
|
Site type |
Mineral |
Peat |
|
Slope |
Absent |
Present |
|
Soil type |
Luvisolic, Gleysolic |
Organic, Cryosolic |
|
Year before PC1 |
Colder sites in the previous year |
Warmer sites in the previous year |
|
Year before PC 2 |
High seasonality of the weather in the previous year |
Low seasonality of the weather in the previous year |
|
Year before PC3 |
Short growing season |
Long growing season |
Biotic |
Forest type |
Black spruce/larch, White spruce |
No trees |
|
Tree stand characteristics PC1 |
Low tree density |
High tree density |
|
Tree stand characteristics PC2 |
More dead trees |
More living trees |