Effects of elevated CO₂, nitrogen and phosphorus on the growth and photosynthesis of two upland perennials: Calluna vulgaris and Pteridium aquilinum

Abstract

SUMMARYBracken {Pteridium aquilinum (L.) Kuhn) and heather {Calluna vulgaris (L.) Hull) are important upland species which often grow in close proximity in the UK. The effects of factorial treatments of elevated atmospheric COj (539/<mol mol"' as opposed to ambient atmospheric COj concentrations of 355/*mol mor*), added N (50 kg N ha-i as NH^NO^) and added P (20 kg P ha-' as NaH^PO^) on the performance of these two species were studied under controlled environmental conditions using container-grown plants. Plants grown and measured at high COj had higher rates of net photosynthesis than those grown and measured in ambient COg. This increase was greater in heather than in bracken and resulted in a large stimulation of growth in the former. In bracken there was no significant change in plant size or phenology. The increase in biomass of heather in high CO2was greatest in the absence of added nutrients and lowest when both N and P were supplied. The growth and photosynthesis of both plants responded positively to the supply of P alone or P with N (in both CO^ atmospheres), but there was little response to N alone. The implications of these findings for bracken and heather growing in the field under conditions of an elevated CO^ atmosphere and greater nutrient availability are discussed.

The effect of nutrient supply and light intensity on tannins and mycorrhizal colonisation in Dutch heathland ecosystems

“…-N inputs become immobilised in the heath more layer (Adams 1986, Whitehead et al 1997, Kristensen and Hendriksen 1998. Furthermore, the difference between the response to nutrient supply in terms of the amount of mycorrhizal colonisation of heather roots in the field and greenhouse experiments might be explained by the fact that only in the greenhouse was it possible to establish strong nitrogen-limited conditions.…”

“…Only the first year growth of green leaves was sampled. For proper handling of the leaf material prior to analyses, we followed the guidelines described in Waterman and Mole (1994). The leaf material was kept cool and brought to the laboratory where it was frozen immediately (-18°C) until handled for analyses.…”

“…All analyses were performed in duplicate. Given the problems and complexities of applying an appropriate standard for the proanthocyanidin method (Waterman and Mole 1994), the data are presented as final absorbance at 550 nm. Another portion of dried leaves (70°C) was pulverised and C and N concentrations were measured using an elemental analyser (Fisons Instruments, EA 1108).…”

“…The mixture was covered and placed in a water bath (75°C) for 1 h. The sample was then filtered through a glass filter and the extract adjusted to 50 ml with 50% (v/v) methanol. Total phenolics were determined following the Folin-Ciocalteu method (Waterman and Mole 1994). Condensed tannins were analysed following the butanol-HCl method of Porter et al (1986).…”

Physiological and molecular alterations in plants exposed to high [CO2] under phosphorus stress

“…However, the rate of enhancement of photosynthetic rate of plants under elevated CO 2 depends upon P availability. Higher P supply under elevated [CO 2 ] further enhances the photosynthetic rate (Duchein et al, 1993;Whitehead et al, 1997;Almeida et al, 1999 …”