PhD defence: Feng Tian

Feng Tian defends his PhD thesis:

Earth Observation of vegetation dynamics in global drylands — Evaluating long-term optical and microwave datasets and analyzing woody vegetation trends

Supervisor

Associate Professor Rasmus Fensholt, IGN 

Assessment Committee

Associate Professor Alexander Prishchepov, IGN (chair)

Associate Professor Jonas Ardö, Lund University

Research Director Jean-Pierre Wigneron, INRA

After the PhD defence there will be a reception in Rød stue, Øster Voldgade 10, Area 6, First floor – everybody is welcome.

Abstract

Land degradation in global drylands has been a concern related to both the local livelihoods and the changes in terrestrial biosphere, especially in the context of substantial global environmental changes. Earth Observation (EO) provides a unique way to assess the vegetation dynamics over the past decades, which are keys to understanding the changes in global drylands. However, there are still large uncertainties and unknowns in the quality and capabilities of remote sensing data. This thesis contributes to an improved EO based assessment of dryland vegetation dynamics by 1) evaluating and exploring the widely used long-term datasets and 2) mapping trends in woody vegetation.

A highlight of the thesis is the mapping of trends in the non-green woody vegetation component in global tropical drylands, which is obtained for the first time from combing satellite optical and passive microwave observations. Trends in the woody component are found to be significant (p < 0.05) in 35% of the areas characterized by a non-significant trend in the leaf component, indicating a pronounced gradual growth/decline in woody vegetation not captured by traditional assessments. The thesis also reveals contrasting trends in the woody cover between humid areas and drylands in Africa, which are explained by human activities and climate changes, respectively.

The thesis is available from the PhD administration office 04.1.417