Document Type
Article
Journal/Book Title/Conference
Global Change Biology
Author ORCID Identifier
A. Joshua Leffler https://orcid.org/0000-0002-3389-2493
Karen H. Beard https://orcid.org/0000-0003-4997-2495
Katharine C. Kelsey https://orcid.org/0000-0002-4631-8538
Ryan T. Choi https://orcid.org/0000-0003-2020-5671
Joel A. Schmutz https://orcid.org/0000-0002-6516-0836
Jeffrey M. Welker https://orcid.org/0000-0002-3865-4822
Volume
25
Issue
1
Publisher
Wiley-Blackwell Publishing Ltd.
Publication Date
10-8-2018
First Page
277
Last Page
289
Abstract
The advancement of spring and the differential ability of organisms to respond to changes in plant phenology may lead to “phenological mismatches” as a result of climate change. One potential for considerable mismatch is between migratory birds and food availability in northern breeding ranges, and these mismatches may have consequences for ecosystem function. We conducted a three-year experiment to examine the consequences for CO2 exchange of advanced spring green-up and altered timing of grazing by migratory Pacific black brant in a coastal wetland in western Alaska. Experimental treatments represent the variation in green-up and timing of peak grazing intensity that currently exists in the system. Delayed grazing resulted in greater net ecosystem exchange (NEE) and gross primary productivity (GPP), while early grazing reduced CO2 uptake with the potential of causing net ecosystem carbon (C) loss in late spring and early summer. Conversely, advancing the growing season only influenced ecosystem respiration (ER), resulting in a small increase in ER with no concomitant impact on GPP or NEE. The experimental treatment that represents the most likely future, with green-up advancing more rapidly than arrival of migratory geese, results in NEE changing by 1.2 µmol m−2 s−1 toward a greater CO2 sink in spring and summer. Increased sink strength, however, may be mitigated by early arrival of migratory geese, which would reduce CO2 uptake. Importantly, while the direct effect of climate warming on phenology of green-up has a minimal influence on NEE, the indirect effect of climate warming manifest through changes in the timing of peak grazing can have a significant impact on C balance in northern coastal wetlands. Furthermore, processes influencing the timing of goose migration in the winter range can significantly influence ecosystem function in summer habitats.
Recommended Citation
Leffler AJ, Beard KH, Kelsey KC, Choi RT, Schmutz JA, Welker JM. Delayed herbivory by migratory geese increases summer-long CO2 uptake in coastal western Alaska. Glob Change Biol. 2019; 25: 277–289. https://doi.org/10.1111/gcb.14473