Impact of simulated changes in rainfall regime and nutrient deposition on the relative dominance and isotopic composition of ruderal plants in anthropogenic grasslands
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).
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.
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.
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.
Keywords13C 18O Foliar nutrients Drought Nutrient deposition Global change Ruderal species Roadside grasslands
We wish to thank Santiago Soliveres for his useful comments and corrections on a previous version of this manuscript. Virginia Sanz, Cristina Alcala and Enrique Pigem helped during the field and laboratory work. PGP was supported by a PhD fellowship from Proyecto Expertal, funded by Fundación Biodiversidad and CINTRA. FTM is supported by the European Research Council under the European Community’s Seventh Framework Programme (FP7/2007–2013)/ERC Grant agreement n° 242658 (BIOCOM). JIQ is supported by the Spanish Ministry of Science (CGL2010-21064). This research was supported by the EXPERTAL, EFITAL (B007/2007/3-10.2) and REMEDINAL (S0505/AMB/0335) projects, funded by Fundación Biodiversidad-Cintra S.A., Ministerio de Medio Ambiente and the Comunidad de Madrid, respectively.
- Barbour MM, Fischer RA, Sayre KD, Farquhar GD (2000) Oxygen isotope ratio of leaf and grain material correlates with stomatal conductance and yield in irrigated, field-grown wheat. Aust J Plant Physiol 27:625–637Google Scholar
- Bobbink R, Hicks K, Galloway J, Spranger T, Alkemade R, Ashmore M, Bustamante M, Cinderby S, Davidson E, Dentener F, Emmett B, Erisman JW, Fenn M, Gilliam F, Nordin A, Pardo L, De Vries W (2010) Global assessment of nitrogen deposition effects on terrestrial plant diversity: a synthesis. Ecol Appl 20:30–59PubMedCrossRefGoogle Scholar
- Cape JN, Tang YS, van Dijk N, Love L, Sutton MA, Palmer SCF (2004) Concentrations of ammonia and nitrogen dioxide at roadside verges, and their contribution to nitrogen deposition. Env Pollut 132:469–478Google Scholar
- Dukes JS, Chiariello NR, Cleland EE, Moore LA, Shaw MR, Thayer S, Tobeck T, Mooney HA, Field CB (2005) Responses of grassland production to single and multiple global environmental changes. PLoS Bio 3:1829–1837Google Scholar
- García-Palacios P, Maestre FT, Gallardo G (2011a) Soil nutrient heterogeneity modulates ecosystem responses to changes in the identity and richness of plant functional groups. J Ecol 99:551–562Google Scholar
- García-Palacios P, Maestre FT, Chapman SJ, Soliveres S, Bowker MA, Gallardo A, Valladares F, Guerrero C, Escudero A (2011b) Early-successional vegetation changes after roadside prairie restoration modify processes related with soil functioning by changing microbial functional diversity. Soil Biol Biochem 43:1245–1253CrossRefGoogle Scholar
- Gotelli NJ, Ellison AM (2004) A primer of ecological statistics. Sinauer Associates, SunderlandGoogle Scholar
- Grime JP (2001) Plant strategies, vegetation processes, and ecosystem properties. John Wiley & Sons, New YorkGoogle Scholar
- IPCC (2007) Climate change 2001: Impacts, adaptation and vulnerability. International Panel of Climate Change, GenevaGoogle Scholar
- Phoenix GK, Hicks WK, Cinderby S, Kuylenstierna JCI, Stock WD, Dentener FJ, Giller KE, Austin AT, Lefroy RDB, Gimeno BS et al (2006) Atmospheric nitrogen deposition in world biodiversity hotspots: the need for a greater global perspective in assessing N deposition impacts. Glob Chang Biol 12:470–476CrossRefGoogle Scholar
- Sala OE, Lauenroth WK, McNaughton J, Rusch G, Zhang X (1996) Biodiversity and ecosystem functioning in grasslands. In: Mooney HA, Cushman JH, Medina E, Sala OE, Schulze ED (eds) Functional roles of biodiversity: a global perspective. Wiley, Chichester, pp 129–149Google Scholar
- Spellerberg IF (1998) Ecological effects of roads and traffic: a literature review. Glob Ecol Biogeogr Let 7:317–333Google Scholar
- UNESCO (1962) Land use in semi-arid Mediterranean climates. International Geographical Union Symposium. UNCESCO, ParisGoogle Scholar