Lanhui Wang: Behind and Beyond the Greening Earth -Coupled terrestrial vegetation phenology and productivity under global climate change and human land management

Lanhui Wang, Department of Geosciences and Natural Resource Management (IGN), defends his PhD thesis:

Behind and Beyond the Greening Earth:
Coupled terrestrial vegetation phenology and productivity under global climate change and human land management

Supervisor
Professor Rasmus Fensholt, IGN

Assessment Committee
Professor Mark Friedl, Boston University
Associate professor Jan Verbesselt, Wageningen University
Associate Professor Thomas Friborg (chair), IGN

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

Summary
The structure and functioning of global terrestrial ecosystems are rapidly changing in response to widespread global environmental change in the Anthropocene, especially to the accelerating anthropogenic climate change and increasingly intensive human land-use change and management. Among those ecosystem changes, the satellite-observed Greening Earth (i.e., increasing total vegetation productivity) and changing land surface phenology (e.g., extending growing season length) is in the spotlight, because they are closely related and could have significant implications for changes in global biogeochemical cycles and climate regulation.

However, a comprehensive global understanding of the relative role of changing phenology and productivity and their interplay in influencing the Greening Earth and increasing gross carbon uptake of global terrestrial ecosystems is still lacking. Focusing on the long-term spatiotemporal coupling of terrestrial vegetation phenology and productivity during either or both the entire growing season and its phenological sub-seasons (e.g., greenup period), three research questions were asked in this thesis: 1) Where and to what extent can the Greening Earth be explained by the warming-induced extension in the length of vegetation growing season? 2) Has the velocity of global vegetation greenup, defined as the daily rate of change in vegetation productivity during greenup period, accelerated or decelerated due to changes in spring phenology and photosynthetic productivity? 3) Has the seasonality (quantity and seasonal distribution) of global terrestrial gross carbon uptake (GPP) been altered in response to global environmental change? These are answered through characterizing the coupled long-term spatiotemporal dynamics of terrestrial vegetation phenology and productivity under global climate change and human land management from three different analytical angles or approaches proposed in this thesis, which provide an improved understanding of global change ecology and pave new pathways to advance it.

The thesis is available from the PhD administration.