Climate impacts on pioneer saltmarsh plants

Climate Research

Alan J. Gray¹  Rebecca J. Mogg¹ 

关键词: Spartina anglica;    Puccinellia maritima;    C4 and C3 photosynthesis;    Elevational niche;    Competition;    Elevated temperature and CO2 enrichment;    Saltmarsh range extension;   

DOI  :  10.3354/cr018105

来源: Inter-Research Science Publishing

【 摘 要 】

ABSTRACT: The 2 grass species that dominate the lower zones of North European saltmarshes utilise different photosynthetic pathways. Puccinellia maritima, a C₃ species, occurs at higher elevations than Spartina anglica, aC₄ species, which is a relatively recent invader and appears not to form extensive swards in latitudes north of ~54°N because of the limiting effect of low early-season temperatures and the greater competitive ability of Puccinellia. Weinvestigate the differential responses of the 2 grasses to rising temperatures and CO₂ concentrations in the light of earlier work that predicts increases in their primary production, assuming a 3°C rise in temperature and a doubling ofatmospheric CO₂. Predictions of their responses to climate change are made using evidence from present day competitive interactions in relation to marsh elevation and latitude, and from a competition experiment in which the 2 species were grownunder ambient and elevated temperature (+3°C) and ambient and enriched CO₂ (+340 ppm) in all factorial combinations. Puccinellia biomass was significantly increased, as expected, by CO₂ enrichment and, probably fromincreasing early-season growth, by elevated temperature; the effect appeared additive, with the highest yield at the +3°C +340 ppm treatment. Spartina growth increased as predicted in response to elevated temperature, but also unexpectedly in highCO₂ treatment, possibly through increased efficiency in water-use. Competition was largely asymmetric in favour of Puccinellia, affecting Spartina height and shoot weight, with intraspecific effects on tiller production and totalbiomass; Spartina mainly responded to both treatments and competition by increased below-ground growth. These results are compared with other, single-factor, experiments and suggest that, depending critically on some other aspects of climate changesuch as rising relative sea level and nutrient dynamics, Spartina is likely to extend its range northwards as CO₂ and temperatures rise, but Puccinellia will continue to replace it in the succession, and probably at lower marshelevations than at present.

【 授权许可】

Unknown