Table 3 Number and meaning of environmental factor classification based on the principle of chi-square binning

AAP (mm)

8

 < 850; 850–950; 950–1000; 1000–1350; 1350–1450; 1450–1500; 1500–1550; > 1550

AAT (°C)

8

 < 11.5; 11.5–16.0; 16.0–17.0; 17.0–17.5; 17.5–18.0; 18.0–18.5; 18.5–19.0; > 19.0

IM (%)

8

 < 45; 45–50; 50–55; 55–60; 60–65; 65–70; 70–90; > 90

AR (%)

8

 < 62; 62–66; 66–68; 68–72; 72–74; 74–92; 92–95; > 95

BIO2

8

 < 7.3; 7.3–7.8; 7.8–7.9; 7.9–8.2; 8.2–8.6; 8.6–9.3; 9.3–9.9; > 9.9

BIO7

8

 < 24; 24–27.5; 27.5–29; 29–31; 31–31.5; 31.5–33; 33–33.5; > 33.5

BIO10 (°C)

8

 < 17; 17–20; 20–22; 22–25; 25–26.5; 26.5–27; 27–28; > 28

BIO11 (°C)

8

 < 5.8; 5.8–6.0; 6.0–6.2; 6.2–6.4; 6.4–6.6; 6.6–7.6; 7.6–8.6; > 8.6

BIO16 (mm)

8

 < 440; 440–460; 460–480; 480–500; 500–520; 520–540; 540–560; > 560

BIO17 (mm)

8

 < 20; 20–50; 50–130; 130–140; 140–155; 155–160; 160–175; > 175

LF

6

Plains; terraces; hills; small undulating mountains; medium undulating mountains; large undulating mountains

LD

7

Paddy field; dry land; woodland; grassland; water area; urban and rural residential land; unused land

EL (m)

7

 < 50; 50–100; 100–450; 450–700; 700–2150; 2150–2500; > 2500

SLOPE (°)

8

 < 2; 2–3; 3–6; 6–9; 9–13; 13–22; 22–29; > 29

DST (km)

8

 < 0.5; 0.5–1.0; 1.0–1.5; 1.5–2; 2–2.5; 2.5–3; 3–3.5; > 3.5

ANDVI

8

 < 0.78; 0.78–0.79; 0.79–0.8; 0.8–0.81; 0.81–0.82; 0.82–0.83; 0.83–0.84; > 0.84

GDP

(10 000/km²)

7

 < 50; 50–100; 100–150; 150–250; 250–350; 350–800; 800–1000; > 1000

DP (Person/km²)

8

 < 100; 100–150; 150–200; 200–250; 250–400; 400–450; 450–550; > 550

NTL

8

 < 0.08; 0.08–0.10; 0.10–0.12; 0.12–0.14; 0.14–0.16; 0.16–0.18; 0.18–0.54; > 0.54