Ecohydrological Controls on Grass and Shrub Above-ground Net Primary Productivity in a Seasonally Dry Climate

Authors

Anthony J. Parolari, Marquette UniversityFollow
Michael L. Goulden, University of California, Irvine
Rafael L. Bras, Georgia Institute of Technology

Document Type

Article

Language

eng

Publication Date

12-2015

Publisher

Wiley

Source Publication

Ecohydrology

Source ISSN

1936-0584

Abstract

Seasonally dry, water‐limited regions are often co‐dominated by distinct herbaceous and woody plant communities with contrasting ecohydrological properties. We investigated the shape of the above‐ground net primary productivity (ANPP) response to annual precipitation (P_a) for adjacent grassland and shrubland ecosystems in Southern California, with the goal of understanding the role of these ecohydrological properties on ecosystem function. Our synthesis of observations and modelling demonstrates grassland and shrubland exhibit distinct ANPP‐P_a responses that correspond with characteristics of the long‐term P_a distribution and mean water balance fluxes. For annual grassland, no ANPP occurs below a ‘precipitation compensation point,’ where bare soil evaporation dominates the water balance, and ANPP saturates above the P_awhere deep percolation and runoff contribute to the modelled water balance. For shrubs, ANPP increases at a lower and relatively constant rate across the P_a gradient, while deep percolation and runoff account for a smaller fraction of the modelled water balance. We identify precipitation seasonality, root depth, and water stress sensitivity as the main ecosystem properties controlling these responses. Observed ANPP‐P_aresponses correspond to notably different patterns of rain‐use efficiency (RUE). Grass RUE exceeds shrub RUE over a wide range of typical P_a values, whereas grasses and shrubs achieve a similar RUE in particularly dry or wet years. Inter‐annual precipitation variability, and the concomitant effect on ANPP, plays a critical role in maintaining the balance of grass and shrub cover and ecosystem‐scale productivity across this landscape.

Comments

Accepted version Ecohydrology, Vol. 8, No. 8 (December 2015): 1572-1583. DOI. © 2019 John Wiley & Sons, Inc. Used with permission.

Recommended Citation

Parolari, Anthony J.; Goulden, Michael L.; and Bras, Rafael L., "Ecohydrological Controls on Grass and Shrub Above-ground Net Primary Productivity in a Seasonally Dry Climate" (2015). Civil and Environmental Engineering Faculty Research and Publications. 189.
https://epublications.marquette.edu/civengin_fac/189