The progression in the vegetation greenness (Normalized Difference Vegetation Index; NDVI) is followed in the plant phenology plots on a weekly basis. NDVI is measured by a Crop Circle Handheld System and scans are conducted by moving the sensor steadily forward (ca. 1 meter per second) approximately 75 cm above the vegetation. This results in a measuring footprint of approximately 10 x 45 m. For further details, please refer to the newest BioBasis manual available at the website.