Consequence of forest‐to‐pasture conversion on CH<sub>4</sub> fluxes in the Brazilian Amazon Basin

Steudler, Paul A.; Melillo, Jerry M.; Feigl, Brigitte Josefine; Neill, Christopher; Píccolo, Marisa de Cássia; Cerri, Carlos Clemente

doi:10.1029/96jd01551

Cited by 140 publications

(164 citation statements)

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“…The few published CH 4 uptake rates that were lower than our lowland forest soil were mainly from Amazon forest soils with low sand or high clay contents, while those with larger CH 4 uptake rates were mostly at sites with low clay content (Steudler et al, 1996;Sousa Neto et al, 2011). Indeed, from studies compiled (Table 3), the only significant correlation between annual CH 4 fluxes and site factors for the tropical forests below 800 m elevation was a positive correlation between annual soil CH 4 fluxes and clay contents (R = 0.58, P = 0.02, n = 16).…”

Section: Ch 4 Fluxes From Control Forests In Comparison With Publishementioning

confidence: 99%

Indications of nitrogen-limited methane uptake in tropical forest soils

Veldkamp¹,

Koehler

Corre³

2013

Biogeosciences

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It is estimated that tropical forest soils contribute 6.2 Tg yr⁻¹ (28%) to global methane (CH₄) uptake, which is large enough to alter CH₄ accumulation in the atmosphere if significant changes would occur to this sink. Elevated deposition of inorganic nitrogen (N) to temperate forest ecosystems has been shown to reduce CH₄ uptake in forest soils, but almost no information exists from tropical forest soils even though projections show that N deposition will increase substantially in tropical regions. Here we report the results from two long-term, ecosystem-scale experiments in which we assessed the impact of chronic N addition on soil CH₄ fluxes from two old-growth forests in Panama: (1) a lowland, moist (2.7 m yr⁻¹ rainfall) forest on clayey Cambisol and Nitisol soils with controls and N-addition plots for 9–12 yr, and (2) a montane, wet (5.5 m yr⁻¹ rainfall) forest on a sandy loam Andosol soil with controls and N-addition plots for 1–4 yr. We measured soil CH₄ fluxes for 4 yr (2006–2009) in four replicate plots (40 m × 40 m each) per treatment using vented static chambers (four chambers per plot). CH₄ fluxes from the lowland control plots and the montane control plots did not differ from their respective N-addition plots. In the lowland forest, chronic N addition did not lead to inhibition of CH₄ uptake; instead, a negative correlation of CH₄ fluxes with nitrate (NO₃^–) concentrations in the mineral soil suggests that increased NO₃^– levels in N-addition plots had stimulated CH₄ consumption and/or reduced CH₄ production. In the montane forest, chronic N addition also showed negative correlation of CH₄ fluxes with ammonium concentrations in the organic layer, which suggests that CH₄ consumption was N limited. We propose the following reasons why such N-stimulated CH₄ consumption did not lead to statistically significant CH₄ uptake: (1) for the lowland forest, this was caused by limitation of CH₄ diffusion from the atmosphere into the clayey soils, particularly during the wet season, as indicated by the strong positive correlations between CH₄ fluxes and water-filled pore space (WFPS); (2) for the montane forest, this was caused by the high WFPS in the mineral soil throughout the year, which may not only limit CH₄ diffusion from the atmosphere into the soil but also favour CH₄ production; and (3) both forest soils showed large spatial and temporal variations of CH₄ fluxes. We conclude that in these extremely different tropical forest ecosystems there were indications of N limitation on CH₄ uptake. Based on these findings, it is unlikely that elevated N deposition on tropical forest soils will lead to a rapid reduction of CH₄ uptake

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Section: Ch 4 Fluxes From Control Forests In Comparison With Publishementioning

confidence: 99%

Indications of nitrogen-limited methane uptake in tropical forest soils

Veldkamp¹,

Koehler

Corre³

2013

Biogeosciences

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“…relative expansion of grasslands (Prentice et al 1993;Steudler et al 1996). However, if the amount generated remains constant for each type, then a shift in the proportion of C 3 and C 4 can transfer into a similar shift in the d 13 CH 4 of the emissions.…”

Section: Source Components Of Pih Yd-pb and Lgm Global Methane Invenmentioning

confidence: 99%

“…For AMP, a dD-CH 4 value of K260‰ is currently assigned (Frank Keppler 2006, personal communication 3C soil methane consumption KIEs (expressed by a soil ) are temperature-dependent, and diffusion is important as are land use, soil moisture, ecosystem e.g. King et al (1989), Tyler et al (1994), Martinerie et al (1995), Steudler et al (1996), Reeburgh et al (1997), Ridgwell et al (1999), Brook et al (2000), and Kaplan (2002) figure 7. The resultant flux weighted mean tropospheric input dD-CH 4 (dD in ) is calculated using equation (2.1) and also shown in figure 7.…”

Section: Source Components Of Pih Yd-pb and Lgm Global Methane Invenmentioning

confidence: 99%

Constraining past global tropospheric methane budgets with carbon and hydrogen isotope ratios in ice

Whiticar

Schaefer

2007

Phil. Trans. R. Soc. A.

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Upon closer inspection, the classical view of the synchronous relationship between tropospheric methane mixing ratio and Greenland temperature observed in ice samples reveals clearly discernable variations in the magnitude of this response during the Late Pleistocene (!50 kyr BP). During the Holocene this relationship appears to decouple, indicating that other factors have modulated the methane budget in the past 10 kyr BP. The d 13 CH 4 and dD-CH 4 of tropospheric methane recorded in ice samples provide a useful constraint on the palaeomethane budget estimations. Anticipated changes in palaeoenvironmental conditions are recorded as changes in the isotope signals of the methane precursors, which are then translated into past global d 13 CH 4 and dD-CH 4 signatures. We present the first methane budgets for the late glacial period that are constrained by dual stable isotopes. The overall isotope variations indicate that the Younger Dryas ( YD) and Preindustrial Holocene have methane that is 13 C-and 2 H-enriched, relative to Modern. The shift is small for d 13 CH 4 (approx. 1‰) but greater for dD-CH 4 (approx. 9‰). The YD d 13 CH 4 -dD-CH 4 record shows a remarkable relationship between them from 12.15 to 11.52 kyr BP. The corresponding C-and H-isotope mass balances possibly indicate fluctuating emissions of thermogenic gas. This d 13 CH 4 -dD-CH 4 relationship breaks down during the YD-Preboreal transition. In both age cases, catastrophic releases of hydrates with Archaeal isotope signatures can be ruled out. Thermogenic clathrate releases are possible during the YD period, but so are conventional natural gas seepages.

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“…In the tropics, CH 4 is emitted at high rates from wetlands (Bartlett and Harriss, 1993), and conversion of forest-to-pasture may transform the soils from CH 4 sinks to sources (Steudler et al, 1996). However, regional net emissions are poorly constrained.…”

Section: Introductionmentioning

confidence: 99%

Methane flux, vertical gradient and mixing ratio measurements in a tropical forest

et al. 2011

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Abstract. Measurements of CH 4 mixing ratio, vertical gradients and turbulent fluxes were carried out in a tropical forest (Reserva Biológica Cuieiras), about 60 km north of Manaus, Brazil. The methane mixing ratio and flux measurements were performed at a height of 53 m (canopy height 35 m). In addition, vertical CH 4 gradients were measured within the canopy using custom made air samplers at levels of 2, 16 and 36 m above ground. The methane gradients within the canopy reveal that there is a continuous methane source at the surface. No clear evidence for aerobic methane emission from the canopy was found. The methane fluxes above the canopy are small but consistently upwards with a maximum early in the morning. The measured fluxes are in agreement with the observed CH 4 gradient in the canopy. In the morning hours, a strong canopy venting peak is observed for both CH 4 and CO 2 , but for CO 2 this peak is then superimposed by photosynthetic uptake, whereas the peak lasts longer for CH 4 . Monthly averaged diurnal cycles of the CH 4 mixing ratio show a decrease during daytime and increase during nighttime. The magnitude of the difference in CH 4 mixing ratio between day and night gradually increases throughout the wet season. The fluxes required to explain the nighttime increase are in agreement with the nighttime fluxes measured above the canopy, which implies that the CH 4 increase in the nighttime boundary layer originates from local sources.

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Consequence of forest‐to‐pasture conversion on CH₄ fluxes in the Brazilian Amazon Basin

Cited by 140 publications

References 41 publications

Indications of nitrogen-limited methane uptake in tropical forest soils

Indications of nitrogen-limited methane uptake in tropical forest soils

Constraining past global tropospheric methane budgets with carbon and hydrogen isotope ratios in ice

Methane flux, vertical gradient and mixing ratio measurements in a tropical forest

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Consequence of forest‐to‐pasture conversion on CH4 fluxes in the Brazilian Amazon Basin

Cited by 140 publications

References 41 publications

Indications of nitrogen-limited methane uptake in tropical forest soils

Indications of nitrogen-limited methane uptake in tropical forest soils

Constraining past global tropospheric methane budgets with carbon and hydrogen isotope ratios in ice

Methane flux, vertical gradient and mixing ratio measurements in a tropical forest

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Product

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Consequence of forest‐to‐pasture conversion on CH₄ fluxes in the Brazilian Amazon Basin