High elevation deciduous forests show unexpected sensitivity to extreme heat and drought
Year: 2026
Type: article
Abstract: The year 2022 in Europe was extreme due to prolonged heatwaves and severe drought. We analyse through high-resolution remote sensing the impacts of the extreme year 2022 on the phenology and the occurrence of early crown discoloration of deciduous forests in northern Italy from the lowlands (Monza) to the Prealps (Cernobbio) and the Alps (Valdidentro). We analysed plant phenology using the normalized difference vegetation index (NDVI) of 2244 images of Sentinel-2 (period 2017–2023) and identified by General Regression Model the drivers of early crown discoloration in the year 2022. We also computed the biomass production at peak season using NDVI provided by Landsat. Drought intensity was quantified using vapour pressure deficit (VPD) and Standardized Precipitation Evapotranspiration Index (SPEI) from 2004 to 2023. The extreme year 2022 produced the largest impact at the lowlands, with early crown discoloration occurring 40 days earlier than mean leaf senescence and decrease of biomass production, but high resilience in 2023. Unexpectedly, the year 2022 induced early crown discoloration of 15 days earlier than leaf senescence at the alpine and prealpine sites, with a legacy effect of decreased biomass production in 2023 at the alpine site, suggesting its poor resilience. Early crown discoloration was driven by persistent drought (SPEI) and summer VPD, with relative influence being species and site dependent. The greening of the following year was not affected by the extreme conditions of 2022. The sensitivity of high elevation deciduous forests to extreme heat and drought suggest to assess their future potential resistance and recovery. • The year 2022 in Europe was extreme due to prolonged heatwaves and severe drought. • Extreme climate impacted the phenology and biomass production of deciduous forests. • Thermophilous forests had highest sensitivity with 40 days of early crown discoloration. • Alpine forests suffered early crown discoloration of 15 days in 2022. • Alpine forests are sensitive and poorly resilient to persistent heat and drought.
Source: Ecological Indicators
Authors: Ilaria Bonfanti, Nicoletta Cannone
Institution: University of Insubria
Language: English
Subfield: Ecology
Field: Environmental Science
Domain: Physical Sciences
SDGs: Climate action, Life on land
Open Access status: gold
Estimated APC paid: $3,650
OpenAlex ID: W7125675924