Jyrki Jauhiainen

The fate of NH4NO3 added to Sphagnum magellanicum carpets at five European mire sites

Nitrogen additions as NH4NO3 corresponding to 0 (N0), 1 (N1), 3 (N3) and 10 (N10) g N m-2 yr-1 were made to Sphagnum magellanicum cores at two-week intervals in situ at four sites across Europe, i.e. Lakkasuo (Finland), Männikjärve (Estonia), Moidach More (UK) and Côte de Braveix (France). The same treatments were applied in a glasshouse experiment in Neuchâtel (Switzerland) in which the water table depth was artificially maintained at 7, 17 and 37 cm below the moss surface. In the field, N assimilation in excess of values in wet deposition occurred in the absence of growth, but varied widely between sites, being absent in Lakkasuo (moss N:P ratio 68) and greatest in Moidach More (N:P 21). In the glasshouse, growth was reduced by lowering the water table without any apparent effect on N assimilation. Total N content of the moss in field sites increased as the mean depth of water table increased indicating growth limitation leading to increased N concentrations which could reduce the capacity for N retention. Greater contents of NH4+ in the underlying peat at 30 cm depth, both in response to NH4NO3 addition and in the unamended cores confirmed poor retention of inorganic N by the moss at Lakkasuo. Nitrate contents in the profiles at Lakkasuo, Moidach More, and Côte de Braveix were extremely low, even in the N10 treatment, but in Männikjärve, where the mean depth of water table was greatest and retention absent, appreciable amounts of NO3- were detected in all cores. It is concluded that peatland drainage would reduce the capture of inorganic N in atmospheric deposition by Sphagnum mosses.

Nutrient concentration in shape Sphagna at increased N-deposition rates and raised atmospheric CO2 concentrations

Sphagnum fuscum, S. magellanicum, S. angustifolium and S. warnstorfii were treated with N deposition rates (0, 10, 30 and 100 kg ha-1 a-1) and with four atmospheric CO2 concentrations (350, 700, 1000 and 2000 ppm) in greenhouse for 71–120 days. Thereafter, concentrations of total N, P, K, Ca and Mg in the capitulae of the Sphagna were determined. The response of each species to N deposition was related to ecological differences. With increasing N deposition treatments, moss N concentrations increased and higher N:P-ratios were found, the increase being especially clear at the highest N load. Sphagnum fuscum, which occupies ombrotrophic habitats, was the most affected by the increased nitrogen load and as a consequence the other elements were decreased. Oligotrophic S. magellanicum, wide nutrient status tolerant S. angustifolium and meso-eutrophic S. warnstorfii tolerated better increased N deposition, though there were increased concentrations of Ca and Mg in S. warnstorfii and Mg in S. magellanicum. Nitrogen and P concentrations decreased with raised CO2 concentrations, except for S. magellanicum. This seems to be the first time this kind of response in nutrient concentrations to enhanced CO2 concentration has been shown to exist in bryophytes. The concentration of K clearly decreased in S. fuscum as did the concentration of Mg in the other Sphagna with increasing CO2. Sphagnum angustifolium and S. magellanicum, which are the less specialized species, were the least affected by the CO2 treatments.

Effects of elevated atmospheric CO2 concentration and increased nitrogen deposition on growth and chemical composition of ombrotrophic Sphagnum balticum and oligo-mesotrophic Sphagnum papillosum

Abstract The ombrotrophic Sphagnum balticum (Russ.) C. Jens. and the oligo-mesotrophic Sphagnum papillosum Lindb. were grown at ambient (360 μ11−1) and at elevated (720 μ11−1) atmospheric CO2 concentrations and at different nitrogen deposition rates, varying between 0 and 30kg N ha−1 yr−1. The growth response to elevated atmospheric CO2 differed between species and this difference also varied with the measured growth parameters. Structural biomass of S. papillosum was significantly stimulated by elevated CO2, whereas S. balticum did not respond. In both species, soluble sugar content in the capitula and stems was significantly increased by elevated CO2 in the absence of nitrogen deposition, but not at elevated CO2 and high nitrogen deposition. The ability of both Sphagnum species to respond to elevated CO2 by enhancement of growth was independent of nitrogen deposition level and plant nitrogen status. The response to increased nitrogen addition was in line with the response to elevated CO2; the oligomesotrophic S. papillosum showed an increased growth, while the ombrotrophic S. balticum again did not respond. The species-dependent growth response to elevated CO2 and increased nitrogen deposition, may have considerable implications for interspecific competition between these species. Doubling atmospheric CO2 reduced total nitrogen content in both Sphagnum species. Elevated CO2 did not promote secondary metabolite production, such as soluble phenols. An increase in soluble phenol content in S. papillosum was observed when plants were grown with increased nitrogen deposition.

Policy perils of ignoring uncertainty in oil palm research

Success of the emerging Low Emissions Development paradigm in Southeast Asia depends on mitigating impacts of oil palm (OP) expansion on carbon-dense ecosystems, especially tropical peatlands. To this end, Koh et al. (1) mapped OP planted before 2002 across Peninsular Malaysia, Sumatra, and Borneo to estimate emissions and biodiversity losses from peatland conversion (≈880,000 ha). Unfortunately, emissions scenarios are oversimplified, remote-sensing (RS) methods are unsuitable for OP monitoring, and recommendations for peatland restoration are overstated.