Soil organic C and total N pools in the Kalahari: potential impacts of climate change on C sequestration in savannas
Soil organic C and total N pools in the Kalahari: potential impacts of climate change on C sequestration in savannas
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DOI：
10.1007/s11104-014-2292-5
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发表时间：
2015-11
期刊：
影响因子：
4.9
通讯作者：
K. Dintwe;G. Okin;P. D’Odorico;Tanja Hrast;N. Mladenov;Alina Handorean;A. Bhattachan;Kelly K. Caylor
中科院分区：
文献类型：
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作者：
K. Dintwe;G. Okin;P. D’Odorico;Tanja Hrast;N. Mladenov;Alina Handorean;A. Bhattachan;Kelly K. Caylor
目标气候变化对碳（C）和氮（N）通量的影响尚未完全了解，特别是在稀树草原生态系统中。本研究旨在评估气候变化对稀树草原土壤碳和氮库的潜在影响。方法对南部非洲稀树草原降水梯度上具有一致沙质土壤的四个地点的土壤有机碳（SOC）和总氮（TN）进行量化。在每个站点的 240 个位置采样四个深度：10、30、70 和 120 cm。结果最干燥的站点和最潮湿的站点的 SOC 含量分别为 1,397 g m−2 和 1,982 g m−2。平均碳氮比在最潮湿的地点最高（26±6），在下一个最潮湿的地点最低（15±2）。我们的结果支持该地区固氮能力低的假设，特别是在干燥的南部地区。我们发现，仅在最干燥的情况下，SOC/TN 含量与树高或树质量之间存在显着的空间关系。博茨瓦纳卡拉哈里 (BK) 土壤估计地下含有约 0.99 × 1015g C，其中约 92% 是 SOC。此外，在IPCC RCP4.5和RCP8.5碳排放情景下，预计到本世纪末，地下总碳量将分别降至0.92和0.86 × 1015g C。结论我们的结果提供了对喀拉哈里稀树草原土壤碳储量的深入了解，并表明稀树草原的有机碳储存量可能比目前认为的还要大。目前的气候变化预测以及实地测量表明，随着该地区进入下个世纪变暖和干燥，这些稀树草原的碳储存量未来可能会减少。
AimsThe impacts of climate change on carbon (C) and nitrogen (N) fluxes are not fully understood, especially in savanna ecosystems. This study aimed to assess the potential impacts of climate change in soil C and N pools in the savannas.MethodsSoil organic carbon (SOC) and total nitrogen (TN) were quantified at four sites with consistent sandy soils along a precipitation gradient in the southern Africa savannas. Soils were sampled at 240 locations at each site at four depths: 10, 30, 70 and 120 cm.ResultsThe driest site and the wettest site had the SOC content of 1,397 g m−2and 1,982 g m−2, respectively. Mean C:N ratio was highest (26 ± 6) at the wettest site and lowest at the next-wettest (15 ± 2). Our results support the hypothesis of low nitrogen fixation in the area, particularly in the dry southern region. We found a significant spatial relationship between SOC/TN content and tree height or tree mass only in the driest. The Botswana Kalahari (BK) soil is estimated to contain about 0.99 × 1015g C belowground of which about 92 % is SOC. Furthermore, under IPCC RCP4.5 and RCP8.5 carbon emission scenarios, total belowground C is predicted to drop to 0.92 and 0.86 × 1015g C, respectively by the end of the century.ConclusionsOur results provide insight into soil C stocks in Kalahari savannas and suggest that savannas may be bigger stores of organic C than currently thought. The current climate change projections together with field measurements suggest that C storage in these savannas may decrease in the future as the region warms and dries into the next century.