In a rapidly warming tundra, ecosystems will undergo major environmental changes that are predicted to significantly alter belowground processes such as decomposition of plant litter. Making use of International Tundra Experiment sites (ITEX), which were established approximately two decades ago, we examined the long-term impacts of warming on decomposition. We used the Tea Bag Index (TBI) methodology to measure the annual mass loss (%) of two tea types as a proxy for potential decomposition rates, across five tundra vegetation types. Direct effects of warming were assessed by comparing mass loss within and outside warming manipulations. Indirect effects of warming, such as those caused by warming-induced changes in plant community composition, were assessed through the relationship between mass loss of tea and local biotic and abiotic conditions. We found positive effects of warming on decomposition, although the responses varied between vegetation and tea types. Interestingly, we found support for the indirect influence of long-term warming on decomposition through warming-induced changes in the composition of plant communities. Our findings demonstrate the complexity in decomposition responses to warming across different vegetation types and highlight the importance of long-term legacies of warming in decomposition responses across the Arctic.
Bibliographical noteFunding Information:
The study was financed by the University of Iceland Research Fund (2016 and 2017) and the University Centre in Svalbard, UNIS (grants to I.S.J.). The Agricultural University of Iceland also provided funding from Blikastaðasjóður during the writing process. The authors are grateful for field and lab assistance from Anne-Nikolai Hejkoop, Carmen Klausbruchner, Matteo Petit Bon, Hanna Böhner, Paula Miguel, Ana Judith Russi-Colmenares, Kristen Peck, and Gunnhildur Gísladóttir. We also thank Anne D. Bjorkman, who kindly provided comments on an earlier draft of the manuscript, as well as two anonymous reviewers for comments that greatly improved the manuscript.
- climate warming
- plant–soil interaction
- Tea Bag Index