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Trends in the Start of the Growing Season in Fennoscandia 1982–2011
Norut, P.O. Box 6434, N-9294 Tromsø, Norway
Norwegian Institute for Nature Research (NINA), High North Research Centre on Climate and the Environment, N-9296 Tromsø, Norway
* Author to whom correspondence should be addressed.
Received: 20 July 2013; in revised form: 2 September 2013 / Accepted: 3 September 2013 / Published: 6 September 2013
Abstract: Global temperature is increasing, and this is affecting the vegetation phenology in many parts of the world. In Fennoscandia, as well as Northern Europe, the advances of phenological events in spring have been recorded in recent decades. In this study, we analyzed the start of the growing season within five different vegetation regions in Fennoscandia using the 30-year Global Inventory Modeling and Mapping Studies (GIMMS) NDVI3g dataset. We applied a previously developed pixel-specific Normalized Difference Vegetation Index (NDVI) threshold method, adjusted it to the NDVI3g data and analyzed trends within the different regions. Results show a warming trend with an earlier start of the growing season of 11.8 ± 2.0 days (p < 0.01) for the whole area. However, there are large regional differences, and the warming/trend towards an earlier start of the growing season is most significant in the southern regions (19.3 ± 4.7 days, p < 0.01 in the southern oceanic region), while the start was stable or modest earlier (two to four days; not significant) in the northern regions. To look for temporal variations in the trends, we divided the 30-year period into three separate decadal time periods. Results show significantly more change/trend towards an earlier start of the growing season in the first period compared to the two last. In the second and third period, the trend towards an earlier start of the growing season slowed down, and in two of the regions, the trend towards an earlier start of the growing season was even reversed during the last decade.
Keywords: phenology; start of the growing season; NDVI time series; NDVI3g; Fennoscandia; vegetation regions; temporal trends
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MDPI and ACS Style
Høgda, K.A.; Tømmervik, H.; Karlsen, S.R. Trends in the Start of the Growing Season in Fennoscandia 1982–2011. Remote Sens. 2013, 5, 4304-4318.
Høgda KA, Tømmervik H, Karlsen SR. Trends in the Start of the Growing Season in Fennoscandia 1982–2011. Remote Sensing. 2013; 5(9):4304-4318.
Høgda, Kjell A.; Tømmervik, Hans; Karlsen, Stein R. 2013. "Trends in the Start of the Growing Season in Fennoscandia 1982–2011." Remote Sens. 5, no. 9: 4304-4318.