| AFFILIATIONS | - IDL, University Lisbon, Lisbon, Portugal
- IPMA, Lisbon, Portugal
- IPE, CSIC, Zaragoza, Spain
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| ABSTRACT | This work analyzes the drought impacts on vegetation over the entire Mediterranean basin, with the purpose of determining the vegetation communities, regions and seasons at which vegetation is driven by drought. Our main approach is based on the NDVI time series with an 8 km spatial resolution from the GIMMS dataset and (8 km resolution). Correlation maps between fields of monthly NDVI and the Standardized Precipitation-Evapotranspiration Index (SPEI) at different time scales (1-24 months) were computed for representative months of winter (Feb), spring (May), summer (Aug) and fall (Nov). Results for the period from 1982-2006 show large areas highly controlled by drought, although presenting high spatial and seasonal differences, with a maximum influence in August and a minimum in February (Gouveia et al., 2017). The highest correlation values are observed in February for 3 months’ time scale and in May for 6 and 12 months. The higher control of drought on vegetation in February and May is obtained mainly over the drier vegetation communities (Mediterranean Dry and Desertic) at shorter time scales (3 to 9 months). Additionally, in February the impact of drought on vegetation is lower for Temperate Oceanic and Continental vegetation types and takes place at longer time scales (18-24). The dependence of drought time-scale response with water balance, as obtained through a simple difference between precipitation and reference evapotranspiration, varies with vegetation communities. A similar analysis is performed with the NDVI obtained by the SPOT VEGETATION instrument at a higher resolution (1 km) for the Balkan area for the period 1998-2014, including a detailed analysis of the 2000-2001 major drought event (Páscoa et al., 2018). Although the vulnerability to drought depended on the land cover type, this drought event provoked a decrease in vegetation activity on the entire study area.
References
Gouveia, C.M., Trigo, R.M., Beguería, S., Vicente-Serrano, S.M., 2017. Drought impacts on vegetation activity in the Mediterranean region: An assessment using remote sensing data and multi-scale drought indicators. Global and Planetary Change, 151:15-27.
Páscoa P., Gouveia C., Russo A., Bojariu R., Vicente-Serrano S.M., Trigo R.M., 2018. Vegetation vulnerability to drought on southeastern Europe, Hydrology and Earth System Sciences (submitted).
Acknowledgments
This work was partially supported by the project IMDROFLOOD funded by Fundação para a Ciência e a Tecnologia, Portugal (FCT, WaterJPI/0004/2014). This work was also supported by FCT through UID/GEO/50019/2013 - Instituto Dom Luiz. |