Ralph O. Dubayah

University of Maryland, Department of Geographical Sciences, 2181 Samuel J. LeFrak Hall, 7251 Preinkert Drive, College Park, MD 20742, USA

Ralph Dubayah has taught at the University of Maryland, College Park since 1990, after earning his dissertation from the University of California. His research interests are in the areas of remote sensing, carbon modeling, biodiversity, and surface energy and water balance studies. A common goal of his research is to develop and apply emerging technologies of spatial data acquisition and analysis to address environmental issues at policy-relevant scales. He has been a principal investigator for over 30 NASA projects, including two Interdisciplinary Science Investigations (IDS) in the areas of terrestrial ecology and biodiversity. He has served in various leadership positions in national and international organizations including the Committee on Earth Observation Satellites (CEOS), and the External Science Advisory Board for the Helmholz Alliance on Remote Sensing and Earth System Dynamics. He was the Science Definition Team Leader for the NASA-ISRO Synthetic Aperture (NISAR) mission and current Science Team Member. He is currently the Principal Investigator for the Global Ecosystem Dynamics Investigation (GEDI). Launched in late 2018, GEDI deploys a multi-beam lidar instrument onboard the International Space Station to measure forest vertical structure and biomass.


Understanding the Role of Ecosystem Structure in Tropical Systems: The Global Ecosystem Dynamics Investigation (GEDI)
For over 50 years NASA, along with other international space agencies, has supported important scientific and policy issues related to the present and future states of the Earth’s carbon and water cycles, its climate, its habitat suitability, and other ecosystem services using a constellation of Earth orbiting satellites. Vegetation three-dimensional structure and its above-ground carbon content (biomass) continue to be the most crucial information missing from the observational archive. The most direct and accurate way of obtaining this detailed vertical structure at the resolution and accuracy required is through lidar remote sensing. While airborne lidar remote sensing of the land surface continues to accelerate, a comprehensive view of ecosystem structure within and across the diversity of the Earth’s ecosystems is still largely absent.

To fill this ongoing gap, the Global Ecosystem Dynamics Investigation (GEDI) was recently launched by NASA to the International Space Station. GEDI will provide over 10 billion observations of vegetation vertical structure over the Earth’s temperate and tropical forests. GEDI lidar observations are used to create data sets on canopy height, canopy leaf profiles, topography, and biomass, among others. These are the first set of spaceborne measurements from an instrument specifically designed to measure vegetation structure and form the basis of much anticipated reference data sets. GEDI data will be used by the scientific community for far ranging applications, by themselves, and in fusion with other existing and planned remote sensing observations that together should revolutionize our understanding of ecosystem structure, function, and composition.

In this talk I provide an overview of the GEDI mission. I first discuss its scientific goals and objectives, and explain its rationale within a context of the scientific importance of ecosystem structure for the main application areas of GEDI: carbon balance and biodiversity. I next describe the measurement capabilities of the GEDI lidar instrument and how its observations are used to produce its science products. With this background, I then show early results from the GEDI mission, with a focus on tropical ecosystems. Lastly, I anticipate how GEDI data may be used in fusion with other sensors, and how, collectively, this ensemble of land surface observations positions us at the forefront of a new era in ecological inquiry.

Renske Onstein

Head of research group Evolution & Adaptation, German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Leipzig, Germany

In June 2018, Renske Onstein became junior research group leader in Evolution & Adaptation at the German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig. She obtained her PhD at the University of Zurich, Switzerland, in 2015. Her research focuses on the evolution and diversification of flowering plants in biodiversity hotspots. In her work she often combines evolutionary data, such as genetics or phylogenetics, with ecological information, such as functional traits or plant-animal interactions. Currently, her group investigates the effects of megafaunal animal extinctions, such as giant lemurs, elephant birds and gomphothers, on genetic connectivity, diversification and adaptation of megafaunal-fruited plants on Madagascar and in the Neotropics.


The co-evolutionary dynamics of tropical fruits and frugivores
The interaction between fruits and frugivores (i.e. fruit-eating and seed-dispersing animals) is prominent in tropical rainforests. Both fruits and frugivores have evolved adaptive traits to facilitate their interactions, but whether this could facilitate diversification in a diffuse co-evolutionary scenario remains enigmatic. For example, large, megafaunal fruits (> 4 cm) are primarily dispersed by large-bodied, megafaunal frugivores, which frequently move across long distances. This behaviour may directly affect plant dispersal capacity, gene flow and ultimately speciation of plant populations. I therefore hypothesize that frugivory-related traits have influenced plant diversification, and evaluate this hypothesis in the palm (Arecaceae) family, which comprises >2500 species. Palms occur across all tropical realms and are keystone fruit resource for tropical frugivores. Using an unprecedented palm functional trait database and a phylogenetic comparative framework, I show that the evolution of fruit sizes, growth forms and island colonisations influenced palm speciation rates. Furthermore, I show that Quaternary global changes affected extinction and adaptation rates of palms with large, megafaunal fruits. Last, I provide support for the idea that palm fruit colours co-evolved with colour vision systems in primates. These results emphasize the importance of plant-animal interactions for our understanding of tropical diversification and the generation and maintenance of tropical biodiversity more generally.

Hans Verbeeck

Gent University, CAVElab Computational & Applied Vegetation Ecology, Coupure Links 653, B-9000 Ghent, Belgium

Hans Verbeeck obtained his Master degree in Bio-science Engineering at Ghent University in 2002. After completing his PhD on modelling carbon and water balances of temperate forest in 2007 at the University of Antwerp, he moved to LSCE (Laboratoire des Sciences du Climat et de l’Environnement, France) as a Marie-Curie fellow. In 2015 he became research professor at Ghent University after obtaining an ERC starting grant. He is leading the research group CAVElab (Computational and Applied Vegetation Ecology) which he established in 2015.

With his group he studies vegetation dynamics and biogeochemical cycling in terrestrial ecosystems. He has a broad interest in all types of terrestrial ecosystems, with a strong focus on the ecology of tropical forest ecosystems. Process-based vegetation modelling is the core research tool, but the questions arising from the modelling work require dedicated field work activities. These field work activities are focused on improving uncertain process descriptions within vegetation models and on data-poor regions like the Congo Basin. The major research lines developed within the research group in recent years are: (1) the role of lianas in the climate response of tropical forests (ERC starting grant project TREECLIMBERS), (2) biogeochemical cycles of tropical forests in the context of climate and land-use change, (3) the interaction between functional diversity and biogeochemical cycles in (tropical) forests, (4) methodological aspects of vegetation modelling (5) integration of remote sensing data into vegetation models, (6) study of vegetation structure and biomass using terrestrial laser scanning.


The impact of lianas on the carbon cycle and demography of tropical forests: insights from vegetation models, water isotopes and terrestrial laser scanning
Lianas are an important component of tropical forests, commonly constituting up to 40% of the woody stems and about 35% of the woody species and contributing substantially to forest leaf biomass. Lianas compete strongly with trees for both above- and below-ground resources. Their indirect impact on the carbon balance, due to their influence on tree community dynamics (by increasing mortality and suppressing tree growth), is far larger than their direct contribution to the forest biomass.
Currently tropical forests are experiencing large-scale structural changes, including an increase in liana abundance and biomass. This may eventually reduce the projected carbon sink of tropical forests. Despite their crucial role, no single terrestrial ecosystem model had included lianas so far. Moreover key data on aboveground and belowground competition between lianas and trees was lacking to develop such models. In this talk I will give an overview of the work we did the past five years to close this knowledge gap.
In the first place we collected new data to study liana-tree competition. Based on innovative stable water isotope monitoring we found that lianas have a very shallow root system in wet tropical forest, contrasting the long standing ‘deep-root hypothesis’ for lianas. Secondly we studied the impact of liana load on tree allometry using terrestrial laser scanning. Based on these studies and existing data we started to develop the first vegetation models that account for lianas.
We have included lianas in two vegetation models, a cohort based model (ED2) and an individual based model (FORMIND). We tested both models against data of two field sites in French Guiana and Panama. This analysis allowed us for the first time to study the impact of lianas on the different components of the forest carbon cycle in an integrated way. Our results confirm that lianas reduce forest productivity and biomass significantly. However, the models also allow us to start exploring ecological questions and underlying mechanisms. We therefore explored the ED2 model by a sensitivity analysis to study the role of belowground versus aboveground competition and evaluated the impact of liana proliferation on the forest albedo using radiative transfer modelling.

Anja Rammig

Professorship Land Surface-Atmosphere Interactions, School of Life Sciences Weihenstephan, Technical University of Munich, Germany

Anja Rammig, Assistant Professor for Land Surface-Atmosphere Interactions, Technical University of Munich, TUM School of Life Sciences Weihenstephan, Freising. Anja Rammig was appointed as Assistant Professor for Land Surface-Atmosphere Interactions at Technical University in Munich in 2015. She obtained a PhD in Environmental Sciences from ETH Zurich in 2006. After completion of her PhD, she worked at the Department of Physical Geography and Ecosystem Science at Lund University, and the Potsdam Institute for Climate Impact Research (PIK). Her research focuses on the impact of global environmental change on ecosystems and potential feedbacks to the climate system. She develops and applies simulation models in combination with observational data to project ecosystem responses to climate and land-use change.


Amazon rainforest responses to climate change: New insights from observations and simulation models