Effect of carbon allocation, land use change, and ozone pollution on global crop yields of major cereals: a modelling approach

Camargo Alvarez, Hector Andres ORCID: 0000-0002-8556-7633 (2024). Effect of carbon allocation, land use change, and ozone pollution on global crop yields of major cereals: a modelling approach. University of Birmingham. Ph.D.

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Abstract

Agriculture is currently facing environmental challenges like climate change, air pollution, and land degradation, affecting agricultural productivity and threatening global food security. Besides, the increase in per capita food consumption among medium and high-income population, plus the expected increase in global population to around 9 billion by 2050, will lead to an unprecedented demand for food sustainably produced. To reach this aim, a holistic understanding of agroecosystems and their complexities is required. The Global Gridded Crop Models (GGCMs) have been developed to fullfill this requirement. Therefore, studies about the food systems require accurate crop models with explicit simulations of the productive processes and interactions with the environment.

This thesis aims to contribute to this broad effort to improve the performance of GGCMs by improving the representations of crop growth, stress response and yield with the Lund-Postdam-Jena General Ecosystem Simulator (LPJ-GUESS) model. The improvement focused on three aspects: (1) carbon assimilation and allocation processes, (2) the impact of past land cover change, and (3) the effect of ground-level O3 pollution on crop yields. The thesis evaluated how these factors affect simulated crop production and how the model can assess crop production under different environmental and management conditions at different spatial and temporal scales. Each of the three aspects also represents different types of uncertainty that the model has to address and are finally reflected in the model outputs, such as parameter uncertainty, input uncertainty and structural uncertainty.

LPJ-GUESS was improved, enhancing its capability to replicate yields, crop productivity processes, and the harmful effects on yield and harvest index simulated by the ozone module. These improvements have significant implications for developing more comprehensive and precise crop simulations that account for the complex interactions between crop production, environmental and management factors, and ozone. These advancements contribute to potentially more accurate global and large-scale yield simulations to better understand the impacts of climate change and terrestrial biogeochemical cycles on food production.

Overall, this thesis represents an improvement in the representation of productive crop processes and will increase the consistency of results in strategic research performed with LPJ-GUESS on the global food system. This is critical for researchers and policymakers to meet the current challenges of agriculture in feeding an increasing population in an environmentally and socially sustainable way.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):