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Klaske van Wijngaarden

Candidature

PhD Candidate

Thesis Title

From branch to forest to globe: how do tree choices regarding growth change forest response to elevated CO2?

Research Project

Klaske van Wijngaarden The global carbon budget is constantly updated to increase our understanding and forecast accuracy on global climate change. Carbon sequestration in long-lived woody tissues is important to slow down climate change and keep this greenhouse gas stored for a long period, and forests are indeed a major carbon sink right now. But predictions on changes over time with changing environmental drivers still need to be well constrained. Modellers expressed the need for more observation-based data to predict better what will happen to forest ecosystems when the atmosphere's carbon dioxide (CO2) levels increase.

Free Air Carbon Enrichment (FACE) experiments provide a rare opportunity to make observations of complete ecosystem responses to elevated CO2 (eCO2), building on previous data collection in labs and growth chambers. This project’s data collection takes place in two such experiments; EucFACE at Western Sydney University (Australia) and BIFoR FACE at the University of Birmingham (UK). The main objective is to determine if prolonged exposure to eCO2 has caused changes in biomass allocation in the woody tissues looking further than stem measurements and if the removal of woody tissues in the form of turnover changes under treatment. These two forests contain different species and are exposed to various environmental drivers, such as precipitation, temperature, and wind frequencies, which are expected to impact allocation and turnover. It is, therefore, also important to research what role these drivers play in biomass distribution in the canopies.

To determine the biomass allocation in the canopy, scans were made with a terrestrial laser scanner that will provide detailed copies and a strong basis for accurate biomass distribution trends in each tree. Monthly inventories of litterfall and larger woody debris will be used to determine how much biomass leaves the canopy over time. Together this will give global carbon budget modellers a more accurate basis for estimating the changes caused by eCO2 for the forests of the future.

Publication

Vaessen RW, van Wijngaarden K, Boeschoten L, Knippers R, Durazzo L, Verkuil L, van Kuijk M, (2023) 'Fruit and seed traits and vertebrate–fruit interactions of tree species occurring in Guyana, Suriname, and French Guiana', Ecology, vol.104, no.11, Article no.e4165

Supervisors

Benjamin Smith (PI), Belinda Medlyn (co-supervisor), Joshua Larsen (co-supervisor, University of Birmingham), Thomas Pugh (co-supervisor, University of Birmingham).