Imagi(ni)ng spectroscopy: Understanding functional trait syndromes that lead to ecosystem service potential

Maria J. Santos, Geography, University of Zurich, Zurich, Switzerland, Shruti Khanna, California Department of Fish and Wildlife, Stockton, CA, Martin O. Reader, URPP GCB/Geography, University of Zurich, Zurich, Switzerland and Susan Ustin, Land, Air & Water Resources, University of California Davis, Davis, CA

Background/Question/Methods
The linkage between how communities of organisms’ function and the ecosystem services they enable is challenged by ongoing global change. Climate change and land use change re-distribute organisms likely leading to novel trait syndromes (i.e. trait co-occurrence bundles) to emerge and thus affecting the ecosystem service potential. However, we have been limited in the study of such interlinkages because of mismatches in scales of data and species trait syndrome dynamics and ecosystem service potential. Imaging spectroscopy has shown many options to measure, map and monitor plant traits , enabling unprecedented understanding of trait syndromes dynamics and their relation to ecosystem services.
Here we examine the extent to which trait syndromes, i.e. bundles of co-occurring traits, change over time and predict ecosystem service potential. We utilize imaging spectroscopy data over the large and diverse landscape of the Sacramento-San Joaquin river delta in California to estimate plant traits in aquatic and terrestrial plant communities (emergent aquatic plants and riparian plants), examine their associations to identify trait syndromes, examine how these trait syndromes change over time and how well do they predict ecosystem service potential for the region.
Results/Conclusions
We examined 88 traits retrieved from imaging spectroscopy data over 2004-2008 and 2014-2019, and found that trait syndromes emerge for both terrestrial and aquatic plant communities. These trait syndromes include a combination of traits related to pigments, leaf morphology, leaf biochemistry and water content and lignin, cellulose and salinity traits. We find that emergent plant communities show stronger changes of trait syndromes between the two periods of time in comparison to the riparian communities, suggesting that their ecosystems service potential is more likely to change. To test this hypothesis, we then linked the trait syndromes to a set of co-occurring ecosystem services relevant for delta systems and show that indeed the trait syndromes that were identified and showed greater dynamics were to some extent linked to more variable ecosystem service provisioning. Thus, knowing the relative contribution of individual and trait syndromes to ecosystem service potential is fundamental to understand how to manage restoration and other management actions in order to counteract potential losses of ecosystem service supply potential in highly dynamic systems. These findings also suggest that such a framework could be expandable to other ecosystems, and provide us with a better understanding of conditions under which ecosystem service potential can be ensured and other situations where is more challenging to do so.