Week of field activities in Sierra National Forest (California, USA)

In October 2023, I had the opportunity to participate in an intense week of field activities in the Sierra National Forest, near Fresno (California, USA). The collections were part of researcher Annie Tucker's master's project, whose work entitled “Multi-Scale Drivers of Intra-Catchment Variability in Drought Response: Linking Remote-Sensing, Geophysical, and Ecohydrological Data” sought to understand the multiple factors that control the response of forests to drought at different scales.

Annie and Katherine. Excellent colleagues in the field!

An interesting point about Annie's study: it was conducted in the King's River Experimental Watershed, part of the Southern Sierra Critical Zone Observatory, which was severely affected by the California drought between 2012 and 2016. The research focused on integrating different databases—from remote sensing (LiDAR and NDVI) to field measurements of sap flow, soil moisture, meteorological variables, and, of course, geophysical data on electrical resistivity. This multiscale approach made it possible to assess how topography, lithology, vegetation structure, and subsoil conditions influence both the resistance (ability to continue transpiring during drought) and resilience (ability to recover after drought) of trees.

Data collection in the Sierra National Forest.

During the field campaign, I was able to collaborate specifically on time-lapse Electrical Resistivity Tomography (ERT) acquisitions, performed with the Syscal Pro resistivity meter. These geophysical data were fundamental for investigating the dynamics of water in the subsoil and its relationship with the ecohydrological response of forests.

Time-lapse scheme of Electrical Resistivity Tomography (ERT) using Syscal Pro.

The field team was excellent—competent, fun, and very collaborative. In addition to Annie, researchers Sara Warix and Kathe Kusold also participated, contributing decisively to the success of the campaign.

Remembering how we use certain equipment that we learned about in topography classes at university.

It was an incredible experience, both for the scientific learning and for the direct contact with the nature of the Sierra Nevada and with such an engaged and enthusiastic team.

Sunset in the Sierra National Forest.