Multidecadal analysis of forest growth and albedo in boreal Finland

0461647 - ÚVGZ 2017 RIV NL eng J - Článek v odborném periodiku
Lukeš, Petr - Stenberg, P. - Mottus, M. - Manninen, T. - Rautiainen, M.
Multidecadal analysis of forest growth and albedo in boreal Finland.
International Journal of Applied Earth Observation and Geoinformation. Roč. 52, OCT (2016), s. 296-305. ISSN 0303-2434. E-ISSN 1872-826X
Grant CEP: GA MŠMT(CZ) LM2010007; GA MŠMT(CZ) LO1415
Výzkumná infrastruktura: CzeCOS II - 90061
Institucionální podpora: RVO:67179843
Klíčová slova: Albedo * fAPAR * LAI * NDVI * Time series * Seasonal trends * Forest structure
Kód oboru RIV: EH - Ekologie - společenstva
Impakt faktor: 3.930, rok: 2016

It is well known that forests serve as carbon sinks. In the last 30 years, there has been a steady increase in the growing stock of Finnish forests by nearly a quarter while the area of the forests has remained virtually unchanged. Such increase in forest density together with the availability of detailed forest inventories provided by the Multi-Source National Forest Inventory (MS-NFI) in high spatial resolution makes Finland an ideal candidate for exploring the effects of increased forest density on satellite derived estimates of bio-geochemical products e.g. albedo (directional-hemispherical reflectance, DHR), fraction of photosynthetically active radiation absorbed by canopies (fAPAR), leaf area index (LAI) and normalized difference vegetation index (NDVI) in both current and long-term perspective. In this study, we first used MODIS-based vegetation satellite products for Finnish forests to study their seasonal patterns and interrelations. Next, the peak growing season observations are linked to the MS-NFI database to yield the generic relationships between forest density and the satellite-derived vegetation indicators. Finally, long-term GIMMS3g datasets between 1982 and 2011 (2008 for DHR) are analyzed and interpreted using forest inventory data. The vegetation peak growing season NIR DHR and VIS DHR showed weak to moderate negative correlation with fAPAR, whereas there was no correlation between NIR DHR and fAPAR. Next, we show that the spectral albedos in the near-infrared region (NIR DHR) showed weak negative correlation with forest biomass, basal area or canopy cover whereas, as expected, the spectral albedo in the visible region (VIS DHR) correlated negatively with these measures of forest density. Interestingly, the increase in forest density (biomass per ha) of Finnish forests during the last 30 years was not accompanied by trends in the indicators of vegetation ‘greenness’ and photosynthetic productivity (fAPAR, LAI and NDVI) or in forest albedo (DHR).
Trvalý link: http://hdl.handle.net/11104/0261245