Figure 1

Meteorological stations in northeast China. Red dots represent meteorological stations; the gradient indicates elevation; and black lines mark province boundaries."

Table 1

Maturity types of maize based on annual accumulated temperatures (AAT)"

Figure 2

Spatial zoning of maize maturity types during 1980- 2010. Note: Stable climatic zones (shaded part) suited to varieties of maize classified by the temperature taken to reach maturity: (a) early maturing (EM), (b) mid-maturing (MM), (c) mid-late maturing (MLM), and (d) late maturing (LM). Transitional climatic zones (colored part) suited to varieties of maize classified by the temperature taken to reach maturity: (e) unsuitable for cultivation of maize to extremely early maturing (UST→EEM), (f) extremely early maturing to early maturing (EEM→EM), (g) early to mid-maturing (EM→MM), (h) mid- to mid-late maturing (MM→MLM), and (i) mid-late to late maturing (MLM→LM)."

Figure 3

Validation of maize distribution by comparing with the NLUD map in 2005"

Figure 4

Spatio-temporal changes in AAT during 1980-2010 in NEC. Red dots mark a change significant at 0.05 level."

Figure 5

Changes in area sown to maize with annual accumulated temperature in the 1980s, 1990s, and 2000s"

Figure 6

Dynamics of maize spatial distribution in different zones of maize maturity types in the 1980s (a), 1990s (b), and 2000s (c)"