The study investigates how to effectively detect hydraulic stress and impending mortality in Norway spruce trees caused by spruce bark beetle (Ips typographus) infestations, linking direct physiological measurements of tree decline to UAV-based hyperspectral imagery.
This research provides the first direct evidence linking the hydrological collapse of conifers to specific canopy-level spectral responses. We demonstrate that green-shoulder hyperspectral metrics can provide near-real-time, early detection of beetle infestations, offering a critical window for forest managers to intervene before the beetles spread.

In this study, we linked tree sap flow and transpiration, with cloud cover and altitude. We observed that both shape sap flow responses. We additionally observed that low clouds suppress sap flow; high cloud bases can enhance it.
Roles of sap flow drivers differ between low- and high-altitude cloud days.

Declining low cloud cover could increase boreal forest transpiration over time.

The study provides preliminary evidence that estimating forest VWC is feasible using tomographic L-band radar platforms. These findings suggest that future spaceborne missions may require vertical separation of canopy and ground backscatter (through tomography or interferometry) and subdaily revisit times to effectively capture diurnal water dynamics in forests.

The MHR method provides a more versatile tool for researchers studying forest hydrology. It is ideal for: Fast-growing species that move water rapidly. High-latitude or high-altitude forests where freeze-thaw cycles frequently disrupt standard sensor readings. Low-power, remote monitoring, as the algorithm is easy to implement in standard data loggers without significantly increasing energy. consumption. In short, this method provides a "best of both worlds" solution for measuring tree water use across a much wider range of environmental conditions and species.

In this study we highlight that drought response in boreal forests is not a "one-size-fits-all" phenomenon. Instead, it is driven by a complex, codependent interaction between biological traits (species and size) and the physical environment (topography). These insights are critical for predicting how northern forests will respond to the increasing frequency of extreme climate events.

In this study we aimed to identify "critical wood temperatures" at which the most sap flow occurs, as this process is vital for both embolism repair and syrup production. We speculate that sap flow is strongly influenced by liquid-to-solid and solid-to-liquid phase changes. Freezing exotherms and thawing endotherms—where volume changes but temperature remains constant—likely explain why flow was highest when temperatures were not changing.

Bennet et al, are building a hydrological model of ET, from radar measurements at P band. Work to be presented at IGARRS 26 in Washington, DC, USA.

Monteith, et al estimate tree water content using exclusively radar attenuation and backscatter

Gutierrez Lopez, et al, study how to estimate tree water content from thermal properties and water dielectric