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Table 6 Principal component analysis and Spearman’s rank correlation coefficients between stream variables and principal components for all collections (n = 432)

From: Distribution pattern of black fly (Diptera: Simuliidae) assemblages along an altitudinal gradient in Peninsular Malaysia

Variable

Stream sites

Principal components

Min

Max

Mean ± SE

PC-1

PC-2

PC-3

PC-4

PC-5

Altitude (m)

159.00

1813.00

891.40 ± 30.1

−0.751**

0.268**

0.522**

0.224**

0.049

Temperature (°C)

14.40

28.40

25.30 ± 0.17

0.636**

−0.230**

−0.622**

−0.285**

−0.059

Width (m)

0.12

7.90

2.95 ± 0.11

0.692**

0.322**

−0.132**

0.044

0.037

Depth (m)

0.02

0.85

0.54 ± 0.005

0.616**

0.171

0.34

0.034

0.124

Velocity (m/s)

0.16

1.03

0.42 ± 0.009

0.416**

0.544**

−0.217**

0.115

0.360**

Conductivity (mS/cm)

0.01

0.15

3.48 ± 0.001

−0.297**

0.162

−0.327**

0.001

0.328**

Dissolved oxygen (mg/l)

1.27

17.20

15.77 ± 0.14

0.148

0.336**

−0.051

0.363**

−0.576**

pH

4.32

8.53

5.20 ± 0.04

0.036

−0.080

−0.337**

0.739**

−0.155

Discharge (m3/s)

0.002

1.56

2.23 ± 0.01

0.786**

0.376**

−0.208**

0.049

0.137

Canopy cover

open

complete

2a

0.213**

−0.718**

0.175

0.315**

0.306**

Riparian

open

forest

2a

0.400**

−0.763**

0.174

0.122

−0.015

Streambed

sand

bedrock

3a

0.449**

0.176

−0.503**

0.274**

0.366**

% Variance explained in PCA

      

Proportion

   

24.8

15.1

13.8

9.3

8.4

Cumulative

   

24.8

39.7

53.6

62.8

71.2

  1. ** P < 0.001
  2. aMedian values given for riparian vegetation (1 = open, 2 = brush and 3 = forest), streambed-particle size (min; 1 = mud/silt and max; 6 = bedrock), and canopy cover. (1 = open, 2 = partial and 3 = complete). Rankings followed McCreadie et al. [34]