Regular Article

Plant and Soil

, Volume 352, Issue 1, pp 303-319

Impact of simulated changes in rainfall regime and nutrient deposition on the relative dominance and isotopic composition of ruderal plants in anthropogenic grasslands

  • Pablo García-PalaciosAffiliated withDepartamento de Biología y Geología, Área de Biodiversidad y Conservación, Escuela Superior de Ciencias Experimentales y Tecnología, Universidad Rey Juan Carlos Email author 
  • , José I. QuerejetaAffiliated withDepartamento de Conservación de Suelos y Aguas, Centro de Edafología y Biología Aplicada del Segura, CSIC, Campus Universitario de Espinardo
  • , Fernando T. MaestreAffiliated withDepartamento de Biología y Geología, Área de Biodiversidad y Conservación, Escuela Superior de Ciencias Experimentales y Tecnología, Universidad Rey Juan Carlos
  • , Adrián EscuderoAffiliated withDepartamento de Biología y Geología, Área de Biodiversidad y Conservación, Escuela Superior de Ciencias Experimentales y Tecnología, Universidad Rey Juan Carlos
  • , Fernando ValladaresAffiliated withDepartamento de Biología y Geología, Área de Biodiversidad y Conservación, Escuela Superior de Ciencias Experimentales y Tecnología, Universidad Rey Juan CarlosMuseo Nacional de Ciencias Naturales, MNCN, CSIC

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Abstract

Background and aims

Plant productivity in drylands is frequently co-limited by water and nutrient availability, and thus is expected to be influenced by ongoing changes in rainfall regime and atmospheric nutrient deposition. Roadside grasslands are widespread worldwide, represent ecologically meaningful examples of highly dynamic anthropogenic ecosystems, and are well suited to investigate global change effects on plant performance. We evaluated the effects of changes in water and nutrient availability on the relative dominance and physiological performance of Bromus rubens, Carduus tenuifolius and Melilotus officinalis, which belong to contrasting functional groups (grasses, non-legume forbs and legumes, respectively).

Methods

We conducted a factorial field experiment in two semiarid roadside grasslands in central Spain with the following factors: watering (no water addition vs. watering with 50% of the monthly total precipitation median) and fertilization (no fertilization vs. addition of 80 kg N ha−1 year−1). The cover of the species evaluated, was surveyed over a 2-year period. Plant isotopic composition (leaf δ13C and δ18O) and nutrient concentrations (foliar N, P and K) were used to assess plant ecophysiological performance.

Results

Carduus was able to cope with lower water availability levels through stomatal adjustments without a significant reduction in its relative dominance. The relative dominance of Bromus was negatively affected by even moderate water stress, although elevated nutrient deposition buffered the adverse impact of drought through a nutrient-mediated enhancement of plant water use efficiency. Increased nutrient availability strongly decreased the relative dominance of Melilotus, irrespective of water availability.

Conclusions

Species-specific physiological mechanisms of adjustment to treatments suggest that plant communities in roadside grasslands will not respond as a unit to global environmental change. The characterization of species-specific responses to major global change drivers may improve predictions about the future dynamics of plant communities in novel ecosystems such as roadside slopes.

Keywords

13C 18O Foliar nutrients Drought Nutrient deposition Global change Ruderal species Roadside grasslands