Observing global biodiversity and ecosystem function from space

Background/Question/Methods

The current detailed understanding of the global biodiversity and ecosystem function is poor.  Yet measurement of these properties is required to understand the current state of the Earth’s ecosystems and function as well as to predict future evolutionally pathways in a period of climate change and anthropogenic disturbances.  Strategies for global assessment of ecosystem biodiversity and function are limited by access and the available observables.  Remote measurement by imaging spectroscopy provides an approach to acquire this information through direct observation globally.  A contiguous spectroscopic measurement of the top-of-canopy over the solar reflected spectrum from 380 to 2500 nm gives access to the absorption and scattering signatures of the canopy.  In this spectral range light interacts with plant chlorophyll, ancillary pigments, nitrogen compounds, lignin, cellulose, and water.  In addition, the multiple scattering in the canopy imparts structural information.  These chemical and structural factors can be used to derive the compositional diversity and function of the ecosystem remotely.   

Results/Conclusions

This approach has been tested at the local scale with high fidelity airborne imaging spectrometer measurements that simulate space measurements.  Results showing the mapping of vegetation at the species and functional type level for forest, chaparral and coastal ecosystems are given.  Corresponding results are provided for estimation of ecosystem function from imaging spectroscopy measurements.  Based on more than of a decade of successful exploration and validation with airborne imaging spectrometer measurements, a space mission concept known as HyspIRI is currently in the concept phase at NASA.  This global high fidelity mission will provide direct spectroscopic measurement over all terrestrial ecosystems every 19 days.  This is a potentially enabling mission for global ecosystem research. These measurements will significantly advance our understanding of the Earth’s ecosystem biodiversity and function globally.