Vegetation Productivity Losses Linked to Mediterranean Hot and Dry Events

Abstract

Persistent hot and dry conditions play an important role in vegetation dynamics, being generally associated with reduced activity. In the Mediterranean region, ecosystems are adapted to such conditions. However, prolonged and intense heat and drought or the occurrence of compound hot and dry events may still have a negative impact on vegetation activity. This work aims to study how the productivity of Mediterranean vegetation is affected by hot and dry events, examining a set of severe episodes that occurred in three different regions (Iberian Peninsula, Eastern Mediterranean and Western Europe) between 2001 and 2019. The analysis relies on remote sensing products, namely Gross Primary Production from MODIS to detect and monitor vegetative stress and LST from MODIS and SM from ESA CCI to evaluate the influence of temperature and soil water availability on stressed vegetation. Of all events, the 2005 episode in the Iberian Peninsula was the most significant, affecting large sectors of low tree cover areas and crops and leading to reductions of annual plant productivity in affected vegetation of ~47 TgC/year. The obtained results highlight the influence of land-atmosphere coupling on vegetation productivity and clarified the role of warm springs on vegetation activity and soil moisture that may amplify summer temperatures. The functional recovery of affected vegetation productivity after these episodes varied across events, ranging from months to years. This work highlights the influence of hot and dry events on vegetation productivity in the Mediterranean basin and the usefulness of remote-sensing products to assess the response of different land covers to such episodes.

Mapping the Most Susceptible Regions to Fire in Portugal

“…Portugal is one of the Mediterranean countries with higher burned area extension [10]. Fuel accumulation, steep mountains, and fragmented landscapes due to abandoned rural properties, in association with increasing prolonged droughts and hot conditions such as those in 2003, 2005 or 2017 [55][56][57], are key factors for the enhancement of fire risk in many regions. Therefore, an assessment of the critical areas that show a greater suscep- According to the results, a large extension of A1 revealed high fire susceptibility, especially in the southern part of the fire scar (Figure 8, top panels).…”

The severity of dry and hot climate extremes and their related impacts on vegetation in Madagascar

“…Recent studies have characterized compound events based on distinct statistical approaches, including event coincidence analysis, 27 , 28 , 74 frequency of simultaneous occurrences of multiple extremes, 75 or copula analyses2020b). 19 , 70 , 76 Despite the scientific progress to date, the full comprehension of the mechanistic links associated with compound events is in its early stages.…”

“…Apart from the documented association between droughts and heat extreme events in certain parts of the world, their influence on vegetation activity has been also analyzed during the last years. 5 , 24 , 25 , 26 , 27 , 28 Previous studies pointed out that the depletion of soil water content amplifies high temperatures due to the increase of sensible heat fluxes, 29 leading to a consequent reduction in the transpiration and photosynthetic activity of vegetation, 30 which on the other hand can lead to severe wildfires and consequently to considerable economic, social, and environmental damages. 31 Moreover, the land-atmosphere-vegetation interplay can occur with different levels of damage, even for low-intensity extremes, 32 and its highly dependent on the land cover.…”

Heat and drought events alter biogenic capacity to balance CO2 budget in south-western Europe

“…In France and Central Europe, air temperatures during the summer 2003 were the highest in the last 500 years, which caused a reduction of the continental net carbon uptake in the range of 20 -500 TgC year -1 , and in some regions changing the ecosystems from carbon sinks to carbon sources (Ciais et al, 2005;Reichstein et al, 2007). The Iberian Peninsula experienced droughts in 2004/2005, 2012, 2015, 2017 and 2022, which produced detrimental effects on the ecosystems, and combined with high summer temperatures intensified the occurrence of fires in the territory (Ermitão et al, 2021;Faranda et al, 2023;Ionita et al, 2017;Nunes et al, 2019;Sánchez-Benítez et al, 2018). In Italy, the summers of 2003, 2017 and 2022 with exceptional temperatures which combined with persistent soil water deficits, resulted into extreme impacts on vegetation productivity (Faranda et al, 2023;Rita et al, 2020;Trucchia et al, 2022).…”