Author/Authors :
Karlsen، نويسنده , , Stein Rune and Tolvanen، نويسنده , , Anne and Kubin، نويسنده , , Eero and Poikolainen، نويسنده , , Jarmo and Hّgda، نويسنده , , Kjell Arild and Johansen، نويسنده , , Bernt and Danks، نويسنده , , Fiona S. and Aspholm، نويسنده , , Paul and Wielgolaski، نويسنده , , Frans Emil and Makarova، نويسنده , , Olga، نويسنده ,
Abstract :
Northern Fennoscandia is an ecologically heterogeneous region in the arctic/alpine-boreal transition area. Phenology data on birch from 13 stations and 16-day MODIS-NDVI composite satellite data with 250 m resolution for the period 2000 to 2006 were used to map the growing season. A new combined pixel-specific NDVI threshold and decision rule-based mapping method was developed to determine the onset and end of the growing season. A moderately high correlation was found between NDVI data and birch phenology data. The earliest onset of the growing season is found in the narrow strip of lowland between the mountains and the sea along the coast of northern Norway. The onset follows a clear gradient from lowland to mountain corresponding to the decreasing temperature gradient. In autumn, the yellowing of the vegetation shows a more heterogeneous pattern. The length of the growing season is between 100 and 130 days in 55% of the study area.
Keywords :
Onset of the growing season , End of the growing season , phenology , northern Fennoscandia , MODIS-NDVI , Decision rules
