Daniel Zuleta receives ERC Starting Grant to study hidden carbon losses in forests

Forests’ ability to absorb and store carbon plays an important role in the climate system. Current methods for estimating forest biomass largely track how trees grow and die. But living trees can also lose branches or parts of their crowns and later recover – changes that are difficult to capture with conventional measurements. Daniel Zuleta will investigate these hidden changes in the project TWIG – Beyond mortality: redefining forest biomass dynamics through structural damage and recovery.

“Forest biomass is one of the main ways we measure the climate role of forests. But ground measurements often rely on simple measurements such as trunk diameter and height. They miss part of the story: living trees also lose branches, break crowns, recover and rebuild before they die. If we do not measure those changes, they remain hidden in the uncertainty of forest carbon estimates”, says Daniel Zuleta.

Tracking changes in trees in 3D

The idea behind TWIG dates back to Zuleta’s master’s studies in the Colombian Andes, where he followed branches on hundreds of trees while studying vascular epiphytes. When he returned a year later, many of the branches had fallen.

“I remember thinking that I should have photographed them before and after, because this was something we should be measuring. Today, terrestrial laser scanning lets us reconstruct trunks and crowns in 3D and measure these losses and recoveries directly”, Daniel Zuleta continues. 

TWIG will combine repeated 3D scans of trees with long-term forest inventories. This will allow the researchers to measure how much biomass living trees lose through branch falls and crown damage, and how much they regain as they recover.

The project will also investigate how environmental conditions and tree characteristics influence damage and recovery, and how these processes affect forest structure. The results could improve forest monitoring, remote-sensing measurements and models used to estimate forest carbon stocks and fluxes.

A better picture of forests as carbon sinks

By including damage and recovery in living trees, the researchers hope to produce more accurate estimates of how much carbon forests store and how these stocks change over time.

“Trees are not static objects that simply grow until they die. They lose branches, break crowns, recover and rebuild structure during their lifetime. TWIG will make these hidden changes measurable and connect them to forest monitoring, satellite data and carbon models. In the long term, I hope the project will give us a more accurate picture of how forests respond to global change.”

Record number of applications

Daniel Zuleta from the Department of Biological and Environmental Sciences is the only researcher at the University of Gothenburg to receive an ERC Starting Grant in this year’s call. A total of 421 researchers will share €705 million in funding.

Competition was at a record level, with 4,807 applications submitted – 22 per cent more than in the previous call. Only 8.8 per cent of applications were funded. ERC Starting Grants support researchers at an early stage of their independent careers.