Leaf Area Index – LAI for Wielkopolska agriculture lands
Leaf Area Index – LAI based on NDVI from Sentinel-2
Using the regression equations developed in the course of analyses in Work Package 2 the maps of LAI were generated for both test sites. The maps were produced on the basis of Sentinel-2 images. They show changes in Leaf Area Index throughout the growing season, due to development of plant canopies and agricultural practices. The approach of generating maps of LAI on the basis of relationships between Sentinel-2 based vegetation indices and ground LAI measurements was verified through validation with the use of control points.
The achieved accuracy – mean difference between ground measured LAI and that derived from S-2 NDVI at the beginning of June 2016 was 13 %. It was decided to compare the applied approach with the second method of LAI determination, which is included in the Sen2Agri software package – SNAP module. The comparison of these two approaches, based on the sample of 20 control points, revealed that LAI values are determined with the use of SNAP software are determined with lower accuracy; mean difference between ground measured LAI and that derived from SNAP LAI at the beginning of June 2016 was 35 %, revealing trend of overestimation.
Leaf Area Index – LAI based on SNAP from Sentinel-2
Comparison of LAI derived from S-2 NDVI and from SNAP software – June 5, 2016.
In order to demonstrate LAI variability at particular stages of plant development in the period 2016 – 2018 graphs presenting LAI values were prepared, with the information concerning total rainfall. The precipitation in 2018 in was lower in the period of heading and Milk what influenced lower LAI values in 2018.