Abstract Soil organic carbon (SOC) dynamics along land-use changes influences the terrestrial and global carbon cycle, the climate, soil fertility, agricultural productivity, and food security. Taking soils under native forests as an appropriate ecological reference, we studied changes in soil organic carbon stock along eight land-use types in the highlands of Ethiopia. The general objective of the study was to investigate the dynamics of SOC stock following chrono-sequence land-use/cover systems in the highlands of Ethiopia. The specific objectives were to: (1) analyze loss due to land degradation; (2) analyze gain due to land restoration; and (3) estimate partial balance of SOC stock for the highlands of Ethiopia. The study followed the principle of the Forest Transition Theory (FTT). Eleven sub-areas were considered from the highlands of Ethiopia. A total of 241 auger composite samples from the topsoil (0−20 cm depth) were collected during December 2017 to June 2018, and analyzed at CropNut soil lab in Nairobi. The study results revealed that there were statistically significant variations (P gains in soils of enclosures (3.17 Mg ha−1) > gains in soils of afforestation (2.35 Mg SOC ha−1), which signifies that converting degraded lands to either controlled grazing lands, enclosures, or afforestation would be a promising practice for an enhanced carbon sequestration across the highlands of Ethiopia. This practice is in line with the United Nations’ Sustainable Development Goals. The estimated regional partial stock balance revealed that the loss and gain ratio was 35.1 in 1991, and it declined to 15.4 in 2001, 2.2 in 2011 and 1.8 in 2015. These decreasing ratios indicate the possibility of closing the gap between the losses and the gains in the near future, and eventually shifting to higher rates of gains than losses. It is also important to note that determined efforts towards the effective protection of natural forests and the creation of enclosures and reforestation areas by local communities for enhanced carbon sequestration will benefit them from payments of carbon emission reduction (CER) credits.

中文翻译：

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埃塞俄比亚高地时间序列土地利用系统的土壤有机碳动态

摘要 随着土地利用变化的土壤有机碳 (SOC) 动态影响陆地和全球碳循环、气候、土壤肥力、农业生产力和粮食安全。以原始森林下的土壤为适当的生态参考，我们研究了埃塞俄比亚高地八种土地利用类型的土壤有机碳储量变化。该研究的总体目标是在埃塞俄比亚高地按时间顺序土地利用/覆盖系统调查 SOC 储量的动态。具体目标是：（1）分析土地退化造成的损失；（2）分析土地恢复收益；(3) 估算埃塞俄比亚高地 SOC 储量的部分平衡。该研究遵循森林转型理论（FTT）的原则。从埃塞俄比亚的高地考虑了 11 个分区。2017 年 12 月至 2018 年 6 月期间，共收集了来自表土（0-20 厘米深度）的 241 个螺旋钻复合样品，并在内罗毕的 CropNut 土壤实验室进行了分析。研究结果表明，存在统计学显着变化（围栏土壤中 P 增加（3.17 Mg ha−1）> 造林土壤中 P 增加（2.35 Mg SOC ha−1），这表明将退化土地转化为受控放牧地、围栏或植树造林将是加强埃塞俄比亚高地碳固存的一种有前景的做法。这种做法符合联合国的可持续发展目标。估计的区域部分库存平衡显示损失和收益比为 35.1 1991 年下降到 2001 年的 15.4，2。2011 年为 2，2015 年为 1.8。这些下降的比率表明在不久的将来有可能缩小亏损与收益之间的差距，并最终转向收益高于亏损的比率。同样重要的是要注意，当地社区在有效保护天然林以及建立围栏和重新造林区以增强碳固存方面的坚定努力将使他们受益于碳减排 (CER) 信用的支付。