Table 2 Environmental variables used to forecast the potential suitable habitats of S. lepifera in China.

From: Population decline, potential habitat shifts, and growth reduction of the endangered tree fern Sphaeropteris lepifera in response to changing canopy density

Number

Environment variables

Sample size

1

bio_1

Annual mean temperature (°C)

2

bio_2

Mean diurnal range (Mean of monthly(max temp − min temp))

3

bio_3

Isothermality (Bio2/Bio7) (×100)

4

bio_4

Temperature seasonality (standard deviation ×100)

5

bio_12

Annual precipitation (mm)

6

bio_15

Precipitation seasonality (coefficient of variation)

7

bio_16

Precipitation of wettest quarter (mm)

8

bio_19

Precipitation of coldest quarter (mm)

9

Uvb1_china

Annual Mean UV-B

10

Uvb2_china

UV-B seasonality (standard deviation)

11

Uvb3_china

Mean UV-B of highest month