Ozone impact on ecophysiological processes of forests
Author(s)
Conte, Adriano
Date Issued
December 20, 2020
Type
Doctoral Thesis
Abstract
Tropospheric ozone is a dangerous atmospheric pollutant for forests. It generates oxidative damage to leaves with consequent losses in carbon assimilation. Thresholds for ozone-risk assessment are commonly developed based on manipulative experiments. However, it is not well understood to which extent ozone may have an impact of the ecophysiology of trees in their natural environment. This study focused on the impact of ozone on gross primary productivity (GPP) and Latent Heat (λE)E) fluxes in a Holm Oak forest and a Ponderosa pine plantation, characterized by different tolerance to ozone. Three of most widely used formulations to simulate stomatal conductance (the Jarvis, BWB and Medlyn models) were implemented with ozone impact corrections into the FORCAsT multi-layer canopy model. To evaluate if a phytotoxic threshold exists and if these thresholds are variable across the study sites and during the year, the BWB ozone correction factor was implemented into AIRTREE, a multi-layer canopy model specifically calibrated for both sites. Simulated GPP and λE)E by both models were evaluated against observations by eddy covariance flux towers. Results showed that ozone might reduce the annual GPP up to 13 % in both the study sites and that ozone tolerance of forests changes during the year. With the aim to account for such changes, a Jarvis-like multiplicative model was proposed as a mean to predict a more realistic forest response during the course of the year.
Additional information
Dottorato di ricerca in Scienze, tecnologie e biotecnologie per la sostenibilità
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