Spatial Variation of Soil CO2, CH4 and N2O Fluxes Across Topographical Positions in Tropical Forests of the Guiana Shield

Courtois, Elodie A.; Stahl, Clément; Berge, Joke Van den; Bréchet, Laëtitia; Langenhove, Leandro Van; Richter, Andreas; Urbina, Ifigenia; Soong, Jennifer L.; Peñuelas, Josep; Janssens, Ivan A.

doi:10.1007/s10021-018-0232-6

Cited by 28 publications

(38 citation statements)

References 92 publications

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“…3). The high variability in N 2 O fluxes that we detected over 4 months with our automated system is in agreement with the typical high variability in N 2 O fluxes measured from tropical soils over space and time using static chambers (Arias-Navarro et al, 2017;Courtois et al, 2018). Moreover, N 2 O fluxes did not show any relationship with surface soil humidity (Fig.…”

Section: N 2 O Fluxessupporting

confidence: 89%

“…Longer time series covering at least a full year are needed to explore the seasonal and diurnal variability in fluxes. As highlighted previously in French Guiana (Courtois et al, 2018), spatial variability in CH 4 emission was high, even at a small spatial scale (Figs. 5,6).…”

Section: Ch 4 Fluxessupporting

confidence: 79%

“…6). Tropical soils are generally considered to be a sink at a yearly basis (Dutaur and Verchot, 2007) but it is known that these soils can shift from a source in the wet season to a sink in the dry season (Courtois et al, 2018;Davidson et al, 2008;Teh et al, 2014). No clear temporal trend could be detected during the study period and there was a slight correlation of CH 4 fluxes with surface soil humidity (higher fluxes at intermediate soil humidity, Fig.…”

Section: Ch 4 Fluxesmentioning

confidence: 96%

“…Each week, 4 out of 16 chambers were programmed to stay closed for a longer measurement period to ensure a reliable estimation of low fluxes while the other 12 chambers were programmed to stay closed for a shorter period to capture diel variation and detect high fluxes. For the short closure time (SHORT hereafter), we used a 2 min measurement period because (1) this is a standard closure time for soil CO 2 flux calculations (Janssens et al, 2000), (2) MDF for CO 2 flux is typically low (Epron et al, 2006;Bonal et al, 2008;Bréchet et al, 2009;Courtois et al, 2018), and (3) corresponding MDFs of CH 4 (0.04 nmol m −2 s −1 ) and N 2 O (0.1 nmol m −2 s −1 ) are compatible with the detection of emission or consumption peaks of these two gases in this region (Courtois et al, 2018;Petitjean et al, 2015). For the long closure time (LONG hereafter), we decided to use a 25 min measurement period in order to optimize the trade-off between a reliable estimation of low N 2 O fluxes (Table 1) and a program length that allows for a sufficient number of flux measurements per chamber and per day.…”

Section: Closure Timementioning

confidence: 99%

“…S2), which underlines the complexity of the biological process underlying these fluxes. In a previous study in the same environment (Courtois et al, 2018), we estimated that the minimum detectable flux using gas chromatography analysis of four discrete gas samples over 30 min for N 2 O was ±8.3 µg N m −2 h −1 . MDF estimated in the present study using high-frequency measurement was 0.002 nmol m −2 s −1 or 0.2 µg N m −2 h −1 for N 2 O which is therefore ∼ 40 times lower.…”

Section: N 2 O Fluxesmentioning

confidence: 99%

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Automatic high-frequency measurements of full soil greenhouse gas fluxes in a tropical forest

et al. 2019

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Abstract. Measuring in situ soil fluxes of carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) continuously at high frequency requires appropriate technology. We tested the combination of a commercial automated soil CO2 flux chamber system (LI-8100A) with a CH4 and N2O analyzer (Picarro G2308) in a tropical rainforest for 4 months. A chamber closure time of 2 min was sufficient for a reliable estimation of CO2 and CH4 fluxes (100 % and 98.5 % of fluxes were above minimum detectable flux – MDF, respectively). This closure time was generally not suitable for a reliable estimation of the low N2O fluxes in this ecosystem but was sufficient for detecting rare major peak events. A closure time of 25 min was more appropriate for reliable estimation of most N2O fluxes (85.6 % of measured fluxes are above MDF ± 0.002 nmol m−2 s−1). Our study highlights the importance of adjusted closure time for each gas.

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Section: N 2 O Fluxessupporting

confidence: 89%

Section: Ch 4 Fluxessupporting

confidence: 79%

Section: Ch 4 Fluxesmentioning

confidence: 96%

Section: Closure Timementioning

confidence: 99%

Section: N 2 O Fluxesmentioning

confidence: 99%

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Automatic high-frequency measurements of full soil greenhouse gas fluxes in a tropical forest

et al. 2019

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High foliar K and P resorption efficiencies in old‐growth tropical forests growing on nutrient‐poor soils

Urbina

Grau

Sardans

et al. 2021

Ecology and Evolution

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Resorption is the active withdrawal of nutrients before leaf abscission. This mechanism represents an important strategy to maintain efficient nutrient cycling; however, resorption is poorly characterized in old‐growth tropical forests growing in nutrient‐poor soils. We investigated nutrient resorption from leaves in 39 tree species in two tropical forests on the Guiana Shield, French Guiana, to investigate whether resorption efficiencies varied with soil nutrient, seasonality, and species traits. The stocks of P in leaves, litter, and soil were low at both sites, indicating potential P limitation of the forests. Accordingly, mean resorption efficiencies were higher for P (35.9%) and potassium (K; 44.6%) than for nitrogen (N; 10.3%). K resorption was higher in the wet (70.2%) than in the dry (41.7%) season. P resorption increased slightly with decreasing total soil P; and N and P resorptions were positively related to their foliar concentrations. We conclude that nutrient resorption is a key plant nutrition strategy in these old‐growth tropical forests, that trees with high foliar nutrient concentration reabsorb more nutrient, and that nutrients resorption in leaves, except P, are quite decoupled from nutrients in the soil. Seasonality and biochemical limitation played a role in the resorption of nutrients in leaves, but species‐specific requirements obscured general tendencies at stand and ecosystem level.

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Phosphorus scarcity contributes to nitrogen limitation in lowland tropical rainforests

Vallicrosa

Lugli

Fuchslueger

et al. 2023

Ecology

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There is increasing evidence to suggest that soil nutrient availability can limit the carbon sink capacity of forests, a particularly relevant issue considering today's changing climate. This question is especially important in the tropics, where most part of the Earth's plant biomass is stored. To assess whether tropical forest growth is limited by soil nutrients and to explore N and P limitations, we analyzed stem growth and foliar elemental composition of the five stem widest trees per plot at two sites in French Guiana after 3 years of nitrogen (N), phosphorus (P), and N + P addition. We also compared the results between potential N-fixer and non-N-fixer species. We found a positive effect of N fertilization on stem growth and foliar N, as well as a positive effect of P fertilization on stem growth, foliar N, and foliar P. Potential N-fixing species had greater stem growth, greater foliar N, and greater foliar P concentrations than non-N-fixers. In terms of growth, there was a negative interaction between N-fixer status, N + P, and P fertilization, but no interaction with N fertilization. Because N-fixing plants do not show to be completely N saturated, we do not anticipate N providing from N-fixing plants would supply non-N-fixers. Although the soil-age hypothesis only anticipates P limitation in highly weathered systems, our results for stem growth and foliar elemental composition indicate the existence of considerable N and P co-limitation, which is alleviated in N-fixing plants. The evidence suggests that certain mechanisms invest in N to obtain the scarce P through soil phosphatases, which potentially contributes to the N limitation detected by this study.

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Spatial Variation of Soil CO2, CH4 and N2O Fluxes Across Topographical Positions in Tropical Forests of the Guiana Shield

Cited by 28 publications

References 92 publications

Automatic high-frequency measurements of full soil greenhouse gas fluxes in a tropical forest

Automatic high-frequency measurements of full soil greenhouse gas fluxes in a tropical forest

High foliar K and P resorption efficiencies in old‐growth tropical forests growing on nutrient‐poor soils

Phosphorus scarcity contributes to nitrogen limitation in lowland tropical rainforests

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