HRL verification report : grassland 2015

Abstract

A national coverage exercise was carried out to analyse the effective grassy and non-woody vegetation areas highlighted in the ‘Grassland’ HRL layer using in-situ imagery data and the HRL GRA_2015 provided for verification. The GRA 2015 HRL data layer was superimposed onto the in-situ data namely; Orthoimagery1 (2012), OrthoImagery 2016, the CLC layers (2012, 2018), the national biotope map database layer (updated as of 2011) as well as other in-situ data and input from local expertise

The main product of the “HRL Grassland” is the ‘Grassland’ layer, a grassland/non-grassland mask for the EEA39 area. The grassy and non-woody vegetation baseline product includes all kinds of grassland: managed grassland, semi-natural grassland and natural grassy vegetation. This layer is not directly comparable to the precursor HRL Grassland layer for the reference year 2012.

In Malta’s case, permanent grasslands are practically non-existent and a specific in-situ layer is not available. Hence it was deemed best to apply a complete coverage methodology rather than verifying specific area samples and visually verify the layer using in-situ Orthoimagery and local knowledge. All the major errors identified are categorised as “Commission” or “Omission” error types as per guidelines provided for the verification process. In this case all of the identified errors are of the “Commission” type with a total of 90 cases identified.