Niche construction mediates climate effects on recovery of tundra heathlands after extreme event

RESEARCH ARTICLE Niche construction mediates climate effects on recovery of tundra heathlands after extreme event Victoria T. Gonza´lezID1,2*, Bente Lindgård1, Rigmor Reiersen1, Snorre B. Hagen2, Kari Anne BråthenID1 1 Department of Arctic and Marine Biology, UiT – Arctic University og Norway, Tromsø, Norway, 2 Department of Ecosystems in the Barents Region, NIBIO - Norwegian Institute of Bioeconomy Research, Svanvik, Norway * victoria.gonzalez@nibio.no Abstract Climate change is expected to increase the frequency and intensity of extreme events in northern ecosystems. The outcome of these events across the landscape, might be medi- ated by species effects, such as niche construction, with likely consequences on vegetation resilience. To test this hypothesis, we simulated an extreme event by removing above- ground vegetation in tundra heathlands dominated by the allelopathic dwarf shrub Empe- trum nigrum, a strong niche constructor. We tested the hypothesis under different climate regimes along a 200-km long gradient from oceanic to continental climate in Northern Nor- way. We studied the vegetation recovery process over ten years along the climatic gradient. The recovery of E. nigrum and subordinate species was low and flattened out after five years at all locations along the climatic gradient, causing low vegetation cover at the end of the study in extreme event plots. Natural seed recruitment was low at all sites, however, the addition of seeds from faster growing species did not promote vegetation recovery. A soil

bioassay from 8 years after the vegetation was removed, suggested the allelopathic effect of E. nigrum was still present in the soil environment. Our results provide evidence of how a common niche constructor species can dramatically affect ecosystem recovery along a cli- matic gradient after extreme events in habitats where it is dominant. By its extremely slow regrowth and it preventing establishment of faster growing species, this study increases our knowledge on the possible outcomes when extreme events harm niche constructors in the tundra. Introduction Extreme events are short-term changes in the climate or environment that can have long-term effects. Extreme events can be caused by for example climate change, such as winter warming episodes [1, 2], or increased herbivore disturbance [3] and human activity. These events are PLOS ONE PLOS ONE | https://doi.org/10.1371/journal.pone.0245929 February 4, 2021 1 / 14 a1111111111 a1111111111 a1111111111 a1111111111 a1111111111 OPEN ACCESS Citation: Gonza´lez VT, Lindgård B, Reiersen R, Hagen SB, Bråthen KA (2021) Niche construction mediates climate effects on recovery of tundra heathlands after extreme event. PLoS ONE 16(2): e0245929. https://doi.org/10.1371/journal. pone.0245929 Editor: Craig Eliot Coleman, Brigham Young University, UNITED STATES Received: October 21, 2020 Accepted: January 8, 2021 Published: February 4, 2021 Peer Review History: PLOS recognizes the benefits of transparency in the peer review process; therefore, we enable the publication of all of the content of peer review and author

responses alongside final, published articles. The editorial history of this article is available here: https://doi.org/10.1371/journal.pone.0245929 Copyright: © 2021 Gonza´lez et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Data Availability Statement: Data are available at https://hdl.handle.net/11250/2722169. Funding: The study was funded by a grant from UiT- The Arctic University of Norway provided to