Response of a Sphagnum bog plant community to elevated CO2 and N supply

Wageningen University
Plant Ecology (Impact Factor: 1.46). 08/2002; 162(1):123-134. DOI: 10.1023/A:1020368130679


The response of plant growth to rising CO2 levels appears todepend on nutrient availability, but it is not known whether the growth of bogplants reacts similarly. We therefore studied the effects of elevatedCO2 in combination with N supply on the growth ofSphagnum mosses and vascular plants in ombrotrophic bogvegetation. Because the growth of Sphagnum is lessnutrient-limited than that of vascular plants, we hypothesized thatSphagnum would benefit from elevated CO2. In ourgreenhouse experiment, peat monoliths (34 cm diameter, 40cm deep) with intact bog vegetation were exposed to ambient (350ppmv) or elevated (560 ppmv) atmosphericCO2 combined with low (no N addition) or high (5 g Nm–2 yr–1 added) N deposition for twogrowing seasons. Elevated atmospheric CO2 had unexpected deleterious effectson the growth of Sphagnum
magellanicum, the dominant Sphagnumspecies. Growth was greatly reduced, particularly in the second growing seasonwhen, regardless of N supply, the mosses looked unhealthy. The negativeCO2 effect was strongest in the warmest months, suggesting a combinedeffect of elevated CO2 and the raised temperatures in the greenhouse.High N deposition favored Rhynchospora
alba, which became the dominant vascular plant speciesduring the experiment. Biomass increased more when N supply was high. There wereno significant effects of elevated CO2 on vascular plants, althoughelevated CO2 combined with high N supply tended to increase theaboveground vascular plant biomass. As Sphagnum is the maincarbon-sequestrating species in bogs and rising atmospheric CO2levels are likely to be followed by increases in temperature, there is an urgentneed for further research on the combined effects of elevated CO2 andincreased temperature on Sphagnum growth in bog ecosystems.

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    • "Results of CO 2 fertilization on Sphagnum growth are inconclusive. Increase (Jauhiainen et al. 1998; Heijmans et al. 2001), decrease (Heijmans et al. 2002), and no significant effect (Berendse et al. 2001; Hoosbeek et al. 2001) have been reported. Increase in temperature can enhance tree growth because of higher photosynthesis, longer daily and seasonal growing period, and higher soil nutrient availability (see also section 6.2) (Saxe et al. 2000). "
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    ABSTRACT: Northern peatlands occupy approximately 4% of the global land surface and store about 30% of the global soil carbon (C). A compilation of C accumulation rates in northern peatlands indicated a long-term average rate of C accumulation of 24.1 g m–2 year–1. However, several studies have indicated that on a short-time scale and given the proper conditions, these ecosystems can exhibit very high rates of C accumulation (up to 425 g m–2 year–1). Peatland development is related to precipitation and temperature, and climate change is expected to have an important impact on the C balance of this ecosystem. Given the expected climate change, we suggest that most of the northern forested peatlands located in areas where precipitation is expected to increase (eastern Canada, Alaska, FSU, and Fennoscandia) will continue to act as a C sink in the future. In contrast, forested peatlands of western and central Canada, where precipitation is predicted to decrease, should have a reduction in their C sequestration rates and (or) could become a C source. These trends could be affected by forest management in forested peatlands and by changes in fire cycles. Careful logging, as opposed to wildfire, will facilitate C sequestration in forested peatlands and boreal forest stands prone to paludification while silvicultural treatments (e.g., drainage, site preparation) recommended to increase site productivity will enhance C losses from the soil, but this loss could be compensated by an increase in C storage in tree biomass.Key words: C sequestration, forested peatland, paludification, greenhouse gases, climate change, forest management.
    Environmental Reviews 02/2011; 13(4):199-240. DOI:10.1139/a05-014 · 3.00 Impact Factor
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    • "Recent studies on the relationship between Sphagnum growth and nutrition have been focused on atmospheric nitrogen deposition [11] [12] [13] [14] [15] [16] and many studies showed that enhanced nitrogen deposition accelerates the photosynthetic rate of Sphagnum plants, whereas growth of plants was limited by the deposition of atmospheric ni- trogen. Effects of environmental pollutants on the photosynthesis of Sphagnum plants have also been of great concern . "
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    ABSTRACT: We investigated the temperature dependency of photosynthetic rates for five Sphagnum species: Sphagnum palustre, S. fimbriatum in the Tadewara mire (south-western Japan in a warm-temperate zone) and S. papillosum, S. fuscum, S. fallax in the East Ochiishi mire (north-eastern Japan in a cool-temperate zone) measuring photosynthetic light response within a temperature range between 5 and 40˚C. The maximum photosynthetic rate was obtained at T = 35˚C for S. palustre, S. fuscum and S. papillosum, and at T = 30˚C for S. fimbriatum and S. fallax. Photosynthetic rates of all these species showed a maximum at 300 -500 μmol·m –2 ·s –1 of PPFD and it decreased at higher PPFD (>500 μmol·m –2 ·s –1) under low temperature (5˚C -10˚C). These results imply that Sphagnum species are not fully physiologically adapted to low temperature environments, although Sphagnum species distribute mostly in the circumpolar region.
    American Journal of Plant Sciences 01/2011; 02(05). DOI:10.4236/ajps.2011.25086
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    • "Consequently, R. alba might be less dependent on the applied nutrients for its growth and therefore did not show a response to the added N and P. The N:P ratio in the leaves, however, differed among the nutrient treatments, suggesting that R. alba did use the nutrients to some extent. Studies of Heijmans et al. (2002); Limpens et al. (2003) found an increase in R. alba biomass after N fertilization in intact bog vegetation. Interestingly, both studies determined the increase in this species during the second growing season of the study. "
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    ABSTRACT: Climate warming is likely to increase nutrient mineralization rates in bog ecosystems which may change the plant species composition. We examined the competitive relationships between two graminoid species, Eriophorumvaginatum and Rhynchosporaalba, and two ericoid species, Callunavulgaris and Vacciniumoxycoccus, at different nutrient supply rates. In a greenhouse, the plants were grown in monocultures and mixtures at four nutrient treatments: control, high N, high P, and high N+P. The results show that the ericoids responded more strongly to the nutrient treatments than the graminoids. The dwarf shrubs showed higher growth rates and reduced root:shoot ratio at high N+P supply. When grown in mixture the ericoids increased their growth, while graminoids decreased in biomass or showed signs of nutrient limitation compared to their monoculture plants. This suggests that under increased nutrient availability, bogs are more likely to turn into dwarf shrub dominated ecosystems and not grassland.
    Plant Ecology 09/2009; 204(1):125-134. DOI:10.1007/s11258-009-9574-7 · 1.46 Impact Factor
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