Effects of Temperature, and Nitrogen and Sulfur Deposition, on Methane Emission from a Boreal Mire

CO<sub>2</sub> flux determination by closed-chamber methods can be seriously biased by inappropriate application of linear regression

“…The linear r 2 and the nonlinear R 2 are neither appropriate measures of regression model correctness (often used for checking linearity) nor appropriate filter criteria for measurement performance (Granberg et al, 2001;Huber, 2004;Hibbert, 2005). The expressions (1−r 2 ) and (1−R 2 ) are measures of the unexplained variance normalized to the total variance.…”

Anaerobic Metabolism: Linkages to Trace Gases and Aerobic Processes

“…Granberg et al (2001) evaluated CH 4 emissions from a fen in response to crossed treatments of elevated air temperature, nitrogen deposition, and sulfur deposition. They found that SO|~ additions depressed CH 4 emissions at ambient temperature, but not at elevated temperature.…”

Potential Approaches to Developing Lichen-Based Critical Loads and Levels for Nitrogen, Sulfur and Metal-Containing Atmospheric Pollutants in North America

“…The authors were interested in possible effects of climate change on CH 4 emission, and they expected (and confirmed) sedges to be an important pathway for CH 4 release into the atmosphere. Similar to effects found in ombrotrophic bogs (see section 6.2), sedge cover was significantly increased with an increasing amount of nitrogen addition (Granberg et al, 2001). Unfortunately, the regression analysis used did not permit a distinction between effects found at 15 or at 30 kg N ha -1 yr -1 .…”

“…When sedge cover was accounted for, the effect of nitrogen addition on CH 4 emission changed over the two years of addition from nonsignificant in the first year (1995) to a significant negative effect during the last year (1997). This cumulative effect was probably linked to the significant accumulation of total nitrogen in the upper 5 (15 kg N ha -1 yr -1 treatment) or 10 (30 kg N ha -1 yr -1 treatment) cm of the soil (Granberg et al, 2001). This accumulation corroborated the results found by Francez and Loiseau (1999), who added 5 kg N ha -1 yr -1 labelled with 15 N to a poor fen in Côte de Braveix, Central France (background deposition 10 kg N ha -1 yr -1 ).…”

“…Adding 200 kg N ha -1 yr -1 for 3 years almost doubled biomass at cutting, and stimulated mainly the growth of Filipendula ulmaria, a high growing forb (Van Duren et al, 1997). In a more realistic experiment in northern Sweden, Granberg et al (2001) have simulated increased nitrogen deposition by spraying treatments of 15 and 30 kg N ha -1 yr -1 for three growing seasons, at a ambient deposition of 2 kg N ha -1 yr -1 . The authors were interested in possible effects of climate change on CH 4 emission, and they expected (and confirmed) sedges to be an important pathway for CH 4 release into the atmosphere.…”