Abstract: Vegetation water conservation effect is a hotspot of the researches on the Loess Plateau. The precious researches often ignored the heterogeneity of environmental factors, and conducted at small scale, supposing that the environment is homogenous. By using GIS techniques and giving consideration of the factors (landform and soil), the vegetation water conservation effect and its spatial distribution in the Jinghe River basin of the Loess Plateau were analyzed, with the standard set of vegetation-soil-slope complex at basin scale. The results showed that in the Jinghe River basin, the vegetation average annual water conservation effect was 3.92×10⁸ m³, accourting for 1/3 of the runoff. The total water conservation effect by the vegetations was grassland > farmland > forestland > shrub land, and the average water conservation effect per unit area was farmland > forestland > shrub land > grassland. Being different from previous studies, our study showed that soil played an important role in the vegetation water conservation effect based on grid Unit. As a result, this study could more objectively reflect the vegetation water conservation effect and its spatial distribution at basin scale.

Key words: Phototactic behavior, Dark-adapted time, Helicoverpa armigera 