Science Enabled by New Measurements of Vegetation Structure (ICESat-II, DESDynI, etc.) Some Ecological Considerations Jon Ranson & Hank Shugart Co-Chairs

2 Science Question How are the Earth's carbon cycle and ecosystems changing, and what are the consequences for the Earth's carbon budget, ecosystem sustainability, and biodiversity?* The CARBON CYCLE: Carbon in the atmosphere is a controlling factor on climate and hence on ecological productivity and the sustainability of life. *Earth Science Enterprise Strategy, October 2003 Science Mission Directorate Draft Science Plan, 2006

3 Science Question How are the Earth's carbon cycle and ecosystems changing, and what are the consequences for the Earth's carbon budget, ecosystem sustainability, and biodiversity?* *Earth Science Enterprise Strategy, October 2003 Science Mission Directorate Draft Science Plan, 2006 How are the Earth's carbon cycle and ecosystems changing, and what are the consequences for the Earth's carbon budget?*

4 Science Question Components Carbon in the aboveground biomass of forests represents about 85% of the total carbon in the Earth’s aboveground biomass. Olson et al /ndp/ndp017/ndp017.html Composited NDVI map from MODIS showing global forest extent The question requires measurements of three- dimensional vegetation structure to estimate: (1) Carbon in Aboveground Vegetation (2) Ecosystem Properties

Aboveground biomass and carbon storage Terrestrial vegetation biomass surveys at regional and global scales are fundamental to quantify the strength, location and extent of land carbon sinks and sources. To estimate biomass regionally and globally we must measure forest structure attributes, harvest the trees, weigh all components and develop allometric relationships. Currently measurements can only be done in situ over limited areas. 3-D structure of terrestrial vegetation Critical not only for biomass surveys and biomass change but also for quantifying the location, nature, cause and extent of disturbance in rapidly degrading or recovering terrestrial ecosystems. Current global measurements of carbon in vegetation are very laboriously obtained

To Atmosphere To Land/Ocean Fossil Fuels Land Use Change Ocean Uptake Unidentified (“missing”) Terrestrial Sink Peta (10 15 ) grams of carbon/year Atmospheric Carbon Veg3D will reduce major uncertainties and help to explain the “missing carbon sink.” Largest remaining uncertainties about the Earth’s carbon budget are in its terrestrial components. 4.2 ± ± 0.5 Land Use Change 1.5 ± ± ± 1.5 Global Carbon Budget (Canadell et al., 2007)

Millennium Ecosystem Assessment Synthesis Report (2005) Uncertainty in the magnitude of carbon emissions from land use changes is 66% of the estimated input (1.5 petagrams) Land Use Change 1.5 ± 1.0 To Atmosphere

Fire Climate and human-induced ecosystem changes are reflected strongly in the vertical height and density distribution of vegetation and its horizontal heterogeneity. Both human-induced and natural disturbance are major driving forces that determine the transition of forest stands, landscapes, and regions from carbon sink to source and back again. To Atmosphere To Land/Ocean Fossil Fuels Land Use Change Ocean Uptake Unidentified (“missing”) Terrestrial Sink Peta (10 15 ) grams of carbon/year Atmospheric Carbon Vegetation structure will reduce major uncertainties and help to explain the “missing carbon sink.” Land Use Change 1.5 ± ± 1.5 Global Carbon Budget (Canadell et al., 2007) USA ± China China+China ± USA

The vertical dimension provides key insight into ecosystem state and function based on the heights of canopy and understory Return Intensity Vertical Structure Changes in landscape spatial heterogeneity - vegetation type, height profiles and biomass relate strongly to ecosystem state and condition. Ecosystem structure may change in response to climate. Top – change in tree form from bush to erect Bottom – Pinus siberica appearing in the understory of a Larix forest in Siberia In this radar image from Canada there is evidence of fires ( dark areas at top) and logging (e.g.,black features in center) Horizontal Structure

10 Science Question How are the Earth's carbon cycle and ecosystems changing, and what are the consequences for the Earth's carbon budget, ecosystem sustainability, and biodiversity?* *Earth Science Enterprise Strategy, October 2003 Science Mission Directorate Draft Science Plan, 2006 How are the Earth's carbon cycle and ecosystems changing, and what are the consequences for the Earth's ecosystem sustainability?*

Ecosystem sustainability implies a capacity to measure and predict the state of the planet’s ecosystems. Baobab Grove in N’Xia Pan, Botswana

A Primer on the Dynamics of Forest Ecosystems Tropical Rain Forest Canopy in the Brazilian Amazon

Forest Gap-Dynamics Cycle Lidar Image of Mature Tropical Rain Forest In a mature forest, one expects the canopy to be a mosaic of spatial elements about the size of a large tree crown. These elements go through a cyclical recovery cycle. What do gap dynamics tell us about forest biomass dynamics?

Expected Biomass Change Recovery from Disturbance Carbon Sink Carbon Source Carbon Sink time Mature forest is a mosaic. Carbon disturbance recovery dynamics are non-linear as the all-aged successional patches become desynchronized to produce the mixed- aged mature-forest mosaic. Successional patches recovering from disturbance

Depending on antecedent history, a forest with the biomass level associated with a mature forest, could be storing carbon, losing carbon or staying the same. This means that a single biomass “snapshot” does not completely reveal forest carbon dynamics.

La Selva Footprint Level Height Change ( ) Amplitude Elevation Footprint centers within 3 m

17 Science Question How are the Earth's carbon cycle and ecosystems changing, and what are the consequences for the Earth's carbon budget, ecosystem sustainability, and biodiversity?* *Earth Science Enterprise Strategy, October 2003 Science Mission Directorate Draft Science Plan, 2006 How are the Earth's carbon cycle and ecosystems changing, and what are the consequences for the Earth's biodiversity?*

The three-dimensional structure of vegetation provides habitats for many species and is a control on biodiversity. primary tropical forest Vegetation height and the vertical distribution of leaves and branches influence where and how other species utilize the ecosystem for food, shelter, and territory. Flooded Forest Coastal Redwood Forest Vietnamese Subtropical Forest Eucalyptus forest

The horizontal pattern of habitat-use varies by several orders of magnitude depending on species This implies a need for wall-to-wall coverage of vegetation structure to capture all of these multiple scales