Earth observation derived spectral vegetation indices, such as the Normalized Difference Vegetation Index (NDVI), have been widely used to derive metrics of vegetation dynamics and to characterise spatial and temporal patterns of ecosystem functioning. The use of these metrics for assessing trends in vegetation dynamics is still constrained by uncertainties associated with the use of single-sensor datasets. In this work, we compare metrics describing vegetation dynamics computed from two different satellite sensors (Terra/MODIS and SPOT/VGT2) using NDVI time series to assess the consistency of trends in selected attributes of ecosystem functioning over Northern Portugal. Results showed low consistency in trends of the selected metrics between the two datasets, suggesting that consistency analysis across multiple data sources should be employed when ground validation is not feasible. The proposed multi-sensor approach helps to identify areas where vegetation changes most likely occurred within a target region, supporting the assessment and monitoring of ecosystem functioning.