Investigating drought recovery mechanisms using plant carbon dynamics and foliar spectroscopy

Protecting forests as carbon sinks under future climates requires the ability to predict tree species distributions early enough for management actions to be taken before the onset of a drought event. The ability of an individual to survive drought depends on its ability to recover. However, the physiological mechanisms of recovery are not fully understood.

A tree’s carbohydrate dynamics may be key to understanding drought recovery mechanisms and predicting drought survival. In greenhouse and field studies, the researchers will investigate the role of tree carbohydrate dynamics in drought recovery. They will develop the ability to remotely measure tree carbohydrate dynamics to broadly predict drought recovery and survival before drought onset and streamline measurements of tree carbohydrate dynamics.

To increase participation of underrepresented groups in STEM, they will share interactive activities on forest physiology with K-12 students and teachers from across Montana including rural and tribal communities at annual community engagement events. To broaden participation in undergraduate research and develop a diverse, globally competitive STEM workforce, they will host Research Experiences for Undergraduates internships and lead ‘How to get involved in research’ workshops for natural science majors from underrepresented backgrounds.

To foster an inclusive culture and broaden the institution’s worldview, they will organize a seminar series featuring out-of-state STEM researchers, managers, and professionals from underrepresented backgrounds. To increase public STEM education and science literacy, they will produce a film communicating our research and its impacts to general audiences.

The ability of a tree to recover from drought events of different severities is critical for predicting tree survival in future climates. However, drought recovery mechanisms and plant carbohydrate dynamics are poorly understood because extracting non-structural carbohydrates (NSC) is laborious, and few studies have examined the effect of pre-drought NSC on drought recovery and survival.

In a greenhouse drought-rewatering manipulation experiment on saplings, the investigators will test the hypotheses that maintaining higher pre-drought NSC increases drought survival by increasing the ability to recover, and that more NSC are needed to recover from higher severity drought stress to meet the higher C cost of recovery. They will develop the use of hyperspectral imaging to remotely measure NSC from leaf spectra a) to predict recovery and survival in the greenhouse experiment, and b) to monitor seasonal and daily drought recovery in field-grown trees.

This project leverages interdisciplinary research to answer fundamental unresolved questions such as: what are the physiological mechanisms underlying forest survival? It streamlines NSC assays by remotely measuring NSC from leaf spectra and tackles the pervasive challenge of applying physiology to broad scales. The investigators provide a generalizable approach for using remotely measured NSC dynamics to predict recovery and survival before drought onset in other systems and on broader temporal and spatial scales than what currently exists.

Improving the ability to understand, measure, and scale NSC dynamics in drought recovery will enhance predictions of forest distributions and terrestrial C cycling in future climates.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.