sitesResearch of the LEGATO project focuses on seven‘regions’ of 15 × 15 km (Fig. 1). The three regions in LuzonIsland (Philippines) are denoted as PH 1 to PH 3, the fourregions in Vietnam as VN 1 to VN 4 (Fig. 1). VN 3 andPH 3 are located in mountain areas, where rice is grown onterraces. Two regions are located in the lowland of LuzonIsland (Philippines), two regions are located in the Red Riverarea (Northern Vietnam) and one is located in the MekongDelta (Southern Vietnam).Within each region, five core study ‘landscapes’, consist-ing of a pair of rice fields (or ‘core sites’), were selected. Thedistance between the two rice fields of a pair is ∼150–1000 mEach pair consists of one rice field situated in a homogeneoussurrounding (i.e., other rice fields dominate the surroundingof 100 m radius) and one rice field in a more heterogeneoussurrounding (i.e., the surrounding of 100 m radius is charac-terized by a dominance of non-rice land use such as gardens orforests). Structural heterogeneity will be an important aspectfor LEGATO researchers focusing on links between biodi-versity and crop production. We do not consider it as a factorin the present publication because we focus on factors forlarger-scale differences in Sipalevels between regions.