JIA-2018-09

2113 WANG Qian-feng et al. Journal of Integrative Agriculture 2018, 17(9): 2107–2117 scale. As shown in Fig. 5-A, four ET levels (lower, low, high, and higher) were regionally aggregated. In particular, the northeastern part of the study area showed a higher level of ET and the northwestern and southeastern parts showed lower values, indicating a larger amount of water consumption per unit area in the northeast and a lower amount in the northwest and southeast, mainly due to the variation of vegetation coverage in the region. The pattern is similar to the study of Tang et al. (2011). The spatial pattern of ET for the different types of vegetation was determined and is illustrated in Fig. 5-B–E. Fig. 5-B revealed a higher spatial heterogeneity and a mixture of four levels of ET, mainly due to the change in foliage surface and water consumption associated with crop rotation in the cultivated areas. Fig. 5-C showed that ground coverage mainly comprised of broadleaved deciduous forest has a higher level of ET, principally because groundwater is the main source of ET in forests. Fig. 5-D showed grasslands have a lower ET level, largely because precipitation is the main source of ET in grasslands with little low ET. Fig. 5-E showed that needleleaved forests have a higher ET level, mainly because groundwater recharge is the primary source of ET for a ground coverage of tall trees, but there is little evidence of the highest ET due to thin foliage. The spatial pattern of ET varies for the different types of vegetation, because leaf transpiration and stomatal 140°E A B C E D 42°N 41°N 40°N 39°N 38°N 37°N 42°N 41°N 40°N 39°N 38°N 37°N 42°N 41°N 40°N 39°N 38°N 37°N 42°N 41°N 40°N 39°N 38°N 37°N 42°N 41°N 40°N 39°N 38°N 37°N 42°N 41°N 40°N 39°N 38°N 37°N 42°N 41°N 40°N 39°N 38°N 37°N 42°N 41°N 40°N 39°N 38°N 37°N 42°N 41°N 40°N 39°N 38°N 37°N 42°N 41°N 40°N 39°N 38°N 37°N 115°E 116°E 117°E 118°E 119°E 140°E 115°E 116°E 117°E 118°E 119°E 140°E 115°E 116°E 117°E 118°E 119°E 140°E 115°E 116°E 117°E 118°E 119°E 140°E 115°E 116°E 117°E 118°E 119°E 140°E 115°E 116°E 117°E 118°E 119°E 140°E 115°E 116°E 117°E 118°E 119°E 140°E 115°E 116°E 117°E 118°E 119°E 140°E 115°E 116°E 117°E 118°E 119°E 140°E 115°E 116°E 117°E 118°E 119°E 215 315 415 515 615 ET (mm) Lower Low High Higher Fig. 5 Pattern of evapotranspiration during 2000–2014. A, all the vegetation types. B, farmland. C, broadleaved deciduous forest. D, meandow. E, needlelevaved evergreen forest.