Changes in soil carbon stocks in Brazil due to land use: paired site comparisons and a regional pasture soil survey
Changes in soil carbon stocks in Brazil due to land use: paired site comparisons and a regional pasture soil survey
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DOI：
10.5194/bg-10-6141-2013
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发表时间：
2013-01-01
期刊：
影响因子：
4.9
通讯作者：
Martinelli, L. A.
中科院分区：
文献类型：
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作者：
Assad, E. D.;Pinto, H. S.;Martinelli, L. A.
在这篇论文中，我们计算了巴西的土壤碳储量，研究了17个成对的地点，这些地点的土壤储量在本地植被、牧场和作物-牲畜系统中进行了测定，并在其他区域的采样中包括了100多个牧场土壤，从6.58度到31.53度S，涉及巴西的三个主要生物群：塞拉多、大西洋森林和潘帕。10、30和60 cm土层的天然植被土壤碳储量分别约为29、和92 mg ha(-1)。在配对地点，CPS系统在10 cm和30 cm土层的碳损失分别为7.5mgha(-1)和11.6mgha(-1)。在草地土壤中，10 cm和30 cm土层的碳流失量分别为7.5 mg ha(-1)和11.0 mg ha(-1)。不同土地利用方式下60 cm土层差异不显著。天然植被下10 cm和30 cm土层土壤C-13平均值分别为-25.4‰和-24.0‰，CPS分别为-19.6‰和-17.7‰，草地土壤分别为-18.9‰和-18.3‰，表明C-4碳在这些农业系统中的贡献率不断增加。在牧场土壤的区域调查中，30厘米处的土壤碳储量约为51mgha(-1)，平均增量C-13值为-19.6‰。控制牧场土壤碳储量的主要因素是土壤含沙量和年平均温度。两者加在一起，可以解释土壤碳储量变化的大约一半。将牧场土壤碳储量与Bernoux等人估计的巴西生物群和土壤类型的本地植被的平均土壤碳储量进行比较。(2002)碳增量为6.7 mg ha(-1)，相当于原生植被土壤碳储量的15%。这项研究的结果与我们的牧场地点和地块水平配对研究地点等区域比较在估计土地利用变化引起的土壤碳储量变化方面的差异是一致的。
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 degrees 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 delta C-13 under native vegetation at 10 and 30 cm depth were equal to -25.4 parts per thousand and -24.0 parts per thousand, increasing to -19.6 parts per thousand and -17.7 parts per thousand in CPS, and to -18.9 parts per thousand, and -18.3 parts per thousand 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 delta C-13 value of -19.6 parts per thousand. 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.