Fertiliser application modulates the impact of interannual climate fluctuations and plant-to-plant interactions on the dynamics of annual species in a Mediterranean grassland

ABSTRACT

Background

Climate and land-use changes, which include the application of various types of organic and inorganic fertilisers, have been reducing the species diversity of Mediterranean grasslands and threatening its conservation. Annual plants are one of the most diverse functional groups of species in these grasslands, despite suffering competitive pressure from perennial herbaceous and woody species, and they are essential for ecosystem functioning and stability.

Aims

To quantify how fertilisation modulates the impact of plant-to-plant interactions and climate fluctuations on the dynamics of annuals in Mediterranean grasslands. We hypothesised that the application of sewage sludge would increase competition between functional groups, reducing the abundance of annuals in the long-term, but would buffer the negative impacts of drought on the year-to-year fluctuation of the diversity of annuals.

Methods

In a semi-natural species-rich Mediterranean grassland in northern Spain, we analysed the changes in the taxonomical and functional composition and diversity of annuals over 14 years in response to variations in the abundance of perennial herbaceous and woody species, climate fluctuations and fertilisation with sewage sludge. We quantified separately the patterns of year-to-year fluctuations and long-term trends.

Results

The frequency and diversity of annuals decreased with higher abundance of perennial herbaceous species, drought in June and cold winters. The addition of sewage sludge decreased the abundance of annuals in the long-term, seemed to promote competition between annuals and other functional groups at an interannual scale, and mitigated the negative effects of drought and cold.

Conclusions

Fertilisation influences differently the temporal response of annuals to climate fluctuations and plant-to-plant interactions.

KEYWORDS:

• Annuals
• climate trends
• competition
• fertilisation
• grasslands
• long-term trends
• synchrony
• interannual fluctuations

Acknowledgements

We thank Gobierno de Navarra for cession of the land where the experiment was carried out. We are grateful to Lars Götzenberger for his revision and suggestions to improve earlier versions of the manuscript. We also thank Asociación de Amigos de la Universidad de Navarra, CSIC, Departamento de Educación del Gobierno de Navarra, Fundación Caja Navarra, Ministerio de Ciencia e Innovación and Universidad de Navarra for their funding.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

The data that support the findings of this study will be openly available in Dryad Digital Repository at https://doi.org/10.5061/dryad.66t1g1k3r (Valerio et al. 2022).

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/17550874.2022.2130718

Additional information

Funding

This work was supported by Fundación Caja Navarra under Grant Programa ‘Tú Eliges, Tú Decides’, ref. 10833; and by Universidad de Navarra under Projects ‘Biodiversity Data Analytics and Environmental Quality’ and ‘Red de Observatorios de la Biodiversidad de Navarra (ROBIN)’. M.V. was supported by the Asociación de Amigos de la Universidad de Navarra under Grant Convocatoria de Ayudas para la Formación del Personal Investigador de la Asociación de Amigos de la Universidad de Navarra para el curso 2018-2019 (September 2018-March 2019); and the Departamento de Educación del Gobierno de Navarra under Grant Ayudas predoctorales para la realización de programas de doctorado de interés para Navarra, Plan de Formación y de I+D 2018. A.G. was supported by Ministerio de Ciencia e Innovación under Grant RyC2020-030647-I; and the CSIC under Grant PIE-20223AT003.