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 96:461470. 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


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