Soil greenhouse gas and nutrient dynamics in fertilized western Canadian plantation forests

Abstract

We explored the impacts of fertilization on soil greenhouse gas fluxes and underlying soil nutrient transformations using short-term (up to 7 months) simulated operational fertilization with urea-nitrogen or nitrogen, phosphorus, potassium, and micronutrients in lodgepole pine ( Pinus contorta Dougl. ex Loud. var. latifolia Engelm.), western hemlock ( Tsuga heterophylla (Raf.) Sarge.), and Douglas-fir ( Pseudotsuga menziesii (Mirb.) Franco) forests in British Columbia. Urea appeared to be rapidly mineralized to ammonium, and nitrification (relative to controls) was only observed at the lodgepole pine site and represented only 0.5% of added nitrogen. All sites were small net sinks for atmospheric methane, and fertilization effects, both stimulatory and inhibitory, were short-lived. Across all sites and treatments, soils were as likely to consume as emit nitrous oxide, and among treatment replicates, rates were never significantly different from 0, with the exception of one efflux rate of 1.5 µg·m–2·h–1on the warmest day in the study. We conclude from this pilot study that in acidic, unpolluted (with regard to nitrogen deposition) upland conifer forest soils in western Canada fertilized once or infrequently with urea, ammonium, or a combination of nutrients, the dynamics of soil greenhouse-gas fluxes are generally not disturbed over the short-term, with soils remaining small sinks for atmospheric methane and neutral with regard to flux of nitrous oxide.

Response of CH4 and CO2 fluxes to simulated nitrogen deposition in a boreal forest in the Northeastern China

“…In the boreal forest, N deposition significantly inhibited CH 4 uptake, and the inhibitory effects increased with increasing N treatment levels. These results were consistent with previous findings reporting the inhibition of CH 4 uptake in N-fertilized forest soils [16,44,45]. These authors reported a Meta-analysis revealing that soil CH 4 uptake was significantly reduced 38% across all ecosystems under N application.…”

Soil responses to non-nitrogenous amendments in a nitrogen-saturated temperate forest: an unexpected decrease in methane oxidation after phosphorus and lime addition

“…This is generally consistent with prior soil measurements and high N deposition in the Haliburton Highlands region (Gradowski and Thomas 2008). Relative to other forests with coarse-textured soils elsewhere in Ontario and Canada, soils in our study had slightly higher mean rates of in situ N 2 O emissions (Basiliko et al 2009, Peichl et al 2009). However contrary to our initial predictions, mean in situ N 2 O efflux rates were still low, occasionally negative, and on any given sampling date were not significantly greater than zero (Table 1C; Figure 1).…”

“…Basiliko et al 2009), and liming and P+K fertilization decreased in situ oxidation rates (Table 1C; Figure 1), an unexpected pattern that is discussed below. While controls exhibited the highest level of in situ soil respiration and P+K and P+K+L the lowest, there were no significant average seasonal differences observed (Table 1C; Figure 1).…”

“…Gravimetric water content was determined by oven drying a 5 g subsample. Inorganic, extractable organic and microbial pools of N and P were determined using chloroform-fumigation and potassium persulfate oxidation (Basiliko et al 2009 (Table 1A). This is generally consistent with prior soil measurements and high N deposition in the Haliburton Highlands region (Gradowski and Thomas 2008).…”

Effects of Nitrogen Deposition on CH4 Uptake and CO2 Emission from a temperate forests in Northeastern China

“…Other authors suggest that salts have an inhibitory effort on methanotrophic bacteria due to osmotic stress [29]. Most studies have reported an inhibition of CH 4 uptake in response to N input in forest soils [30][31], although inverse effects have also been reported. The fact that N deposition inhibits CH 4 uptake implies that boreal forests may remove less CH 4 under future increased N deposition conditions in China.…”