MODIS-based forest monitoring
Drought, usually understood as a condition of insufficient moisture, became during last few decades a serious threat to the natural and man-managed ecosystems. Only during last 15 years Europe was struggling with 4 severe heat-waves which effected in extensive drought events. Although, due to the specific location and moderating influence of the alpine climate, resulting meteorological conditions in South Tyrol were not as severe as for the remaining part of the continent, local vegetation systems were clearly affected by precipitation scarcity and heightened temperature, leading in the most extreme cases to the trees dieback (Minebri et al., 2003).
Within the framework of EUFODOS project EURAC is trying to identify the impact, as well as, a footprint of drought events which affected forests of South Tyrol within last 11 years. Because drought influence is understood here as a vegetation stress, and a period of lower productivity, the topic is investigated using Empirical Orthogonal Functions (EOF; Preisendorfer, 1988) approach applied on the MODIS derived 16-day NDVI time series. Time series analyses are complemented by meteorological data (SPI – Standardized Precipitation Index; McKeen et al., 1993) and phonological indicators (Ivits, et al. 2013).
Obtained results show interesting diversity in the drought’s impact and its spatial pattern, suggesting strong connection between vegetation stress, local climatic, as well as, ecological conditions.
- Ivits E., Cherlet M., Sommer S., Mehl W., 2013, Addressing the complexity in non-linear evolution of vegetation phenological change with time-series of remote sensing images, Ecological Indicators, 26, 49-60.
- McKeen T.B., Doesken N.J., Kleist J., 1993, The relationship of drought frequency and duration to time scales, Eighth Conference on Applied Climatology, 17-22 January 1993, Anaheim California
- Minerbi S., Cescatti A., Cherubini P., Hellrigl K., Markart G., Saurer M., Mutinelli C., 2006, Scot Pine dieback in the Isarco Valley due to severe drought in the summer 2003, Forest Observer vol. 2/3, pp 89-144
- Preisendorfer R. W., 1998, Principal Component Analyses in Meteorology and Oceanography, Elsevier