Variation in soil carbon stocks and their determinants across a precipitation gradient in <scp>W</scp>est <scp>A</scp>frica

Saiz, Gustavo; Bird, Michael I.; Domingues, Tomas F.; Schrodt, Franziska; Schwarz, Michael P.; Feldpausch, Ted R.; Veenendaal, E.M.; Djagbletey, Gloria; Hien, F.; Compaoré, Halidou; Diallo, Adama; Lloyd, J.

doi:10.1111/j.1365-2486.2012.02657.x

Cited by 125 publications

(64 citation statements)

References 64 publications

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“…Soils with low OC contents have shown to make relatively larger PyC contributions to total SOC than soils with higher OC contents . Very coarse-textured materials have characteristically low nutrient levels, as well as limited water retention capacities (Schimel et al, 1994;Silver et al, 2000;Saiz et al, 2012), and the associated low net primary productivity may have contributed to the low TOC contents observed in some samples in the present study (Figures 3A, 4). Furthermore, the relatively high proportion of PyC in these sediments suggests the low degree of physicochemical protection that coarse-textured soils offer against OM decomposition, given that a significant proportion of the TOC corresponds to highly recalcitrant PyC material (i.e., HyPyC).…”

Section: Discussion Variation In the Geographical Distribution Of Pycmentioning

confidence: 66%

“…), and on its potential export (e.g., infiltration, erosion, etc.) (Brodowski et al, 2006;Knicker, 2011;Saiz et al, 2012;Singh et al, 2012). Hence, a limited physicochemical protection of OC would promote the preferential mineralization of labile compounds relative to more recalcitrant ones (e.g., PyC).…”

Section: Preferential Combustion Of Grass Biomass and Factors Affectimentioning

confidence: 99%

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Preferential Production and Transport of Grass-Derived Pyrogenic Carbon in NE-Australian Savanna Ecosystems

et al. 2018

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Understanding the main factors driving fire regimes in grasslands and savannas is critical to better manage their biodiversity and functions. Moreover, improving our knowledge on pyrogenic carbon (PyC) dynamics, including formation, transport and deposition, is fundamental to better understand a significant slow-cycling component of the global carbon cycle, particularly as these ecosystems account for a substantial proportion of the area globally burnt. However, a thorough assessment of past fire regimes in grass-dominated ecosystems is problematic due to challenges in interpreting the charcoal record of sediments. It is therefore critical to adopt appropriate sampling and analytical methods to allow the acquisition of reliable data and information on savanna fire dynamics. This study uses hydrogen pyrolysis (HyPy) to quantify PyC abundance and stable isotope composition (δ 13 C) in recent sediments across 38 micro-catchments covering a wide range of mixed C 3 /C 4 vegetation in north Queensland, Australia. We exploited the contrasting δ 13 C values of grasses (i.e., C 4 ; δ 13 C > −15‰) and woody vegetation (i.e., C 3 ; δ 13 C < −24‰) to assess the preferential production and transport of grass-derived PyC in savanna ecosystems. Analyses were conducted on bulk and size-fractionated samples to determine the fractions into which PyC preferentially accumulates. Our data show that the δ 13 C value of PyC in the sediments is decoupled from the δ 13 C value of total organic carbon, which suggests that a significant component of PyC may be derived from incomplete grass combustion, even when the proportion of C 4 grass biomass in the catchment was relatively small. Furthermore, we conducted 16 experimental burns that indicate that there is a comminution of PyC produced in-situ to smaller particles, which facilitates the transport of this material, potentially affecting its preservation potential. Savanna fires preferentially burn the grass understory rather than large trees, leading to a bias toward the finer C 4 -derived PyC in the sedimentary record. This in turn, provides further evidence for the preferential production and transport of C 4 -derived PyC in mixed ecosystems where grass and woody vegetation coexist. Moreover, our isotopic approach provides independent validation of findings derived from conventional charcoal counting techniques concerning the appropriateness of adopting a relatively small particle size threshold (i.e., ∼50 µm) to reconstruct savanna fire regimes Saiz et al. Pyrogenic Carbon Dynamics in Savannas using sedimentary records. This work allows for a more nuanced understanding of the savanna isotope disequilibrium effect, which has significant implications for global 13 C isotopic disequilibria calculations and for the interpretation of δ 13 C values of PyC preserved in sedimentary records.

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Section: Discussion Variation In the Geographical Distribution Of Pycmentioning

confidence: 66%

Section: Preferential Combustion Of Grass Biomass and Factors Affectimentioning

confidence: 99%

Preferential Production and Transport of Grass-Derived Pyrogenic Carbon in NE-Australian Savanna Ecosystems

et al. 2018

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“…At the regional level, climatic variables like temperature and rainfall are important, while at the local level, soil properties like texture, density and fertility are also key variables (Jobbágy and Jackson, 2000;Eclesia et al, 2012;Saiz et al, 2012). We used stepwise regression to choose the best set of variables that control soil carbon stocks.…”

Section: Controls Of Carbon Soil Stocksmentioning

confidence: 99%

Changes in soil carbon stocks in Brazil due to land use: paired site comparisons and a regional pasture soil survey

et al. 2013

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Abstract. In this paper we calculated soil carbon stocks in Brazil studying 17 paired sites where soil stocks were determined in native vegetation, pastures and crop-livestock systems (CPS), and in other regional samplings encompassing more than 100 pasture soils, from 6.58 to 31.53 • S, involving three major Brazilian biomes: Cerrado, Atlantic Forest, and the Pampa. The average native vegetation soil carbon stocks at 10, 30 and 60 cm soil depth were equal to approximately 29, 64, and 92 Mg ha −1 , respectively. In the paired sites, carbon losses of 7.5 Mg ha −1 and 11.6 Mg ha −1 in CPS systems were observed at 10 cm and 30 cm soil depths, respectively. In pasture soils, carbon losses were similar and equal to 7.5 Mg ha −1 and 11.0 Mg ha −1 at 10 cm and 30 cm soil depths, respectively. Differences at 60 cm soil depth were not significantly different between land uses. The average soil δ 13 C under native vegetation at 10 and 30 cm depth were equal to −25.4 ‰ and −24.0 ‰, increasing to −19.6 ‰ and −17.7 ‰ in CPS, and to −18.9 ‰, and −18.3 ‰ in pasture soils, respectively; indicating an increasing contribution of C 4 carbon in these agrosystems. In the regional survey of pasture soils, the soil carbon stock at 30 cm was equal to approximately 51 Mg ha −1 , with an average δ 13 C value of −19.6 ‰. Key controllers of soil carbon stock in pasture sites were sand content and mean annual temperature. Collectively, both could explain approximately half of the variance of soil carbon stocks. When pasture soil carbon stocks were compared with the average soil carbon stocks of native vegetation estimated for Brazilian biomes and soil types by Bernoux et al. (2002) there was a carbon gain of 6.7 Mg ha −1 , which is equivalent to a carbon gain of 15 % compared to the carbon soil stock of the native vegetation. The findings of this study are consistent with differences found between regional comparisons like our pasture sites and plot-level paired study sites in estimating soil carbon stocks changes due to land use changes.

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“…The relationship between precipitation, vegetation, and the accumulation of soil organic matter has been well documented in the literature (Burke et al, 1989;Hontoria et al, 1999;Khormali and Kehl, 2011;Saiz et al, 2012;Zhou et al, 2009). As the quantity and frequency of precipitation increase, net primary production and litter input to the soil rise to a maximum; this rise leads to greater SOC accumulation (Sala et al, 1988;Zhou et al, 2009).…”

Section: Introductionmentioning

confidence: 97%

Relationships between soil organic carbon and precipitation along a climosequence in loess-derived soils of the Central Great Plains, USA

Klopfenstein¹,

Hirmas

Johnson

2015

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Variation in soil carbon stocks and their determinants across a precipitation gradient in West Africa

Cited by 125 publications

References 64 publications

Preferential Production and Transport of Grass-Derived Pyrogenic Carbon in NE-Australian Savanna Ecosystems

Preferential Production and Transport of Grass-Derived Pyrogenic Carbon in NE-Australian Savanna Ecosystems

Changes in soil carbon stocks in Brazil due to land use: paired site comparisons and a regional pasture soil survey

Relationships between soil organic carbon and precipitation along a climosequence in loess-derived soils of the Central Great Plains, USA

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