Four years of experimental warming do not modify the interaction between subalpine shrub species
Climate warming can lead to changes in alpine plant species interactions through modifications in environmental conditions, which may ultimately cause drastic changes in plant communities. We explored the effects of 4 years of experimental warming with open-top chambers (OTC) on Vaccinium myrtillus performance and its interaction with neighbouring shrubs at the Pyrenean treeline ecotone. We examined the effects of warming on height, above-ground (AG) and below-ground (BG) biomass and the C and N concentration and isotope composition of V. myrtillus growing in pure stands or in stands mixed with Vaccinium uliginosum or Rhododendron ferrugineum. We also analysed variations in soil N concentrations, rhizosphere C/N ratios and the functional diversity of the microbial community, and evaluated whether warming altered the biomass, C and N concentration and isotope composition of V. uliginosum in mixed plots. Our results showed that warming induced positive changes in the AG growth of V. myrtillus but not BG, while V. uliginosum did not respond to warming. Vaccinium myrtillus performance did not differ between stand types under increased temperatures, suggesting that warming did not induce shifts in the interaction between V. myrtillus and its neighbouring species. These findings contrast with previous studies in which species interactions changed when temperature was modified. Our results show that species interactions can be less responsive to warming in natural plant communities than in removal experiments, highlighting the need for studies involving the natural assembly of plant species and communities when exploring the effect of environmental changes on plant–plant interactions.
KeywordsDwarf shrub Plant interactions Pyrenees Vaccinium myrtillus Passive warming
Carbon isotope composition
Nitrogen isotope composition
We thank Clara Borrull, Noelia Seguer, Estela Illa, Victoria Lafuente, Elena Lahoz and Santiago Pérez for their field and laboratory assistance. We are grateful to CCiT of the University of Barcelona for the use of their facilities and their technical assistance. This work was supported by Conselh Generau d’Aran and the project ARBALMONT/786-2012 (Organismo Autónomo Parques Nacionales, Ministerio de Agricultura, Alimentación y Medio Ambiente, Spain). AAR was funded by an FPU grant (Ministerio de Educación, Cultura y Deporte, Spain) and SP was funded by a Ramón y Cajal fellowship (RYC-2013-14164, Ministerio de Economía y Competitividad, Spain).
Author contribution statement
AAR, JMN, SP, OG and EC conceived and designed the experiments. AAR, JN and EC performed the experiments in the field. AAR, SP, MCS and EN performed laboratory analyses. AAR and EN analysed the data. AAR wrote the manuscript with the substantial advice, corrections and comments of SP, JMN, OG, EC, SN and EN. All the authors contributed to the discussion of the results.
Compliance with ethical standards
Conflict of interest
All authors declare that they have no conflict of interest.
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