Satellite-derived NDVI underestimates the advancement of alpine vegetation growth over the past three decades

Seasonal dynamics of field-measured biomass. The seasonal biomass dynamics of the plant community have been monitored in a homogeneous grassland area at the study site by harvesting all aboveground green parts of plants once or twice each month per growing season from 1982–2014.<br><br>Time series of satellite-derived NDVI data. We used the Global Inventory Monitoring and Modeling System (GIMMS) third-generation NDVI dataset obtained from the Advanced Very High Resolution Radiometer (AVHRR) sensor. The GIMMS NDVI dataset spanning from July 1981 to December 2014, with a temporal frequency of 15 days and a spatial resolution of 8 km, was downloaded from https://ecocast.arc.nasa.gov/data/pub/gimms/3g.v1/. We also used the Moderate Resolution Imaging Spectroradiometer (MODIS) NDVI product (MOD13Q1, Collection 6). The MODIS NDVI dataset spanning from February 2000 to December 2014, with a temporal frequency of 16 days and a spatial resolution of 250 m, was downloaded from https://lpdaac.usgs.gov/dataset_discovery/modis/modis_products_table/mod13q1_v006. <br>