Google Earth map of the studied arable fields and grasslands

Sites were assigned in the vicinity of 19 villages in the Transylvanian Basin, Romania. Sites are named by the first three letters of the closest village, A (arable) or P (grassland) indicates the land use type, plus H (heterogeneity) and W (woody vegetation cover) values in a 3 value range. Heterogeneity was defined as the standard deviation of the 2.5m panchromatic Spot picture, stratified in quantiles: H1 – belonging to lower third (low heterogeneity), H2 – middle third, H3 – upper third. Woody vegetation cover represented the proportion of woody vegetation (shrubs and trees) in a 1 ha circle based on classified 10m SPOT 5 data: W1: 0 to 5 % woody vegetation cover; W2: 5 to 15 % of woody vegetation; W3: 15 to 50 % of woody vegetation (1 – low, 2 – middle, 3 – high).