What is the impact of reforestation on evapotranspiration ? How can we better assess evapotranspiration in the Atlantic Brazilian Forest ? A case study in Brazil's Atlantic Forest, in São Francisco Xavier, São Paulo State

Details

Supervisors

Javaux, Mathieu ; De Simone Borma, Laura

Faculty

Faculté des bioingénieurs

Degree label

Master [120] : bioingénieur en sciences et technologies de l'environnement, à finalité spécialisée

Abstract

The Brazilian Atlantic Forest has been particularly affected by deforestation in recent decades. The importance of forests in terms of biodiversity and climate regulation noted has led to measures being taken globally for forest conservation and restoration and the Atlantic Forest is no exception. However, concerns have been raised by several scientists and specialists about the water consumption of these young, reforested forests and their impact on water resources in the long term. This master thesis is a continuation of the master thesis made by Basile Delvoie during 2022-2023 and aims to address the uncertainty raised regarding evapotranspiration, a significant flow of the water cycle in tropical forests. This thesis was realized in collaboration with the INPE (Brazil) through the co-promoter of this thesis, Laura Borma. This study was conducted on four plots with a common history but different soil cover at present: A 40-year-old forest (R40), a 10-year-old reforested forest (R10), a pasture (P) and an abandoned area (CA). Various soil properties data were used in this thesis such as water content and water potential data were measured by the INPE from 2019 to 2023. Climatic data (e.g.,: precipitation) were also used. Two methods of estimating of evapotranspiration (SEN-ET and Water Balance) were validated in this thesis, while a third MODIS proved to be inconclusive due to its low resolution of 500m2. Although these two methods do not agree regarding the evapotranspiration of the CA and P zones, due to uncertainties in the calculation of drainage and capillary rise and to limited time and basic data from the sensors used, they both agree that a young, reforested forest (R10) has an evapotranspiration quite similar to that of an old forest (R40) over time with even a lower evapotranspiration in the dry season. During the water balance important capillary rises were even observed for the 40-year-old forest and by analyzing the total water withdrawn compared to the total water produced by the aged forest, it was observed that older forest behave as water consumer rather than producer, which could have a significant impact on water resources in the long term. However, several avenues for improvement have been raised for future research to address the different limitations encountered in this thesis and that will allow to better understand the dynamics of water flows during reforestation.