Deforestation may increase soil carbon but it is unlikely to be continuous or unlimited.
Deforestation may increase soil carbon but it is unlikely to be continuous or unlimited.
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森林砍伐可能会增加土壤碳，但不可能持续或无限制。
DOI：
10.1111/gcb.13999
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发表时间：
2018
影响因子：
11.6
通讯作者：
Schipper L
中科院分区：
文献类型：
--
作者：
Schipper L
确定维持或增强土壤碳储存的土地利用和管理做法对于从大气中螯合碳和改善土壤生态系统服务是重要的（Herrero等人，2016）。关于每年可以在土壤中储存多少额外的碳，以及在土地使用或管理发生变化后储存多长时间（Smith，2014），解决这个问题很重要。在千分之四倡议（4p 1000，2017）中确立的理想目标之后，这一点尤其重要。在一篇题为“亚马逊河流域古老永久牧场的持续土壤碳储存”的论文中，斯塔尔等人（2017年）旨在通过对不同地点的时间序列进行存量测量，显示当热带森林转化为约5.3吨C公顷的放牧牧场时，土壤碳的增加。他们在摘要中说：“......我们的研究结果表明，如果可持续管理应用于热带牧场来自森林砍伐...他们可以确保持续的碳储存”，在讨论中：“这一结果支持了这样一种观点，即某些生态系统，如永久牧场，在长期（即几十年）内不断积累土壤碳。”在后来的结论中：“此外，储存在深层土壤中的腐殖化C可能会提供无限的C积累和长期的C保存。土壤碳的持续和无限制积累肯定会引起研究人员、决策者和广大公众的极大兴趣，因为它是减少温室气体排放的一个重要因素，特别是在每年高达5吨C/ha的情况下。然而，作者的数据或一般文献并不支持连续和无限的碳积累。他们使用从森林到牧场转换的时间序列中的土壤碳储量测量结果，报告说前24年土壤碳没有变化，随后在24年至36年之间土壤碳增加了5吨C ha/年。根据这些数据，在没有进一步理由的情况下推断12年的增长是连续的或无限制的是不合理的。在更广泛的文献中，人们广泛观察到，随着新的平衡的达成，碳在系统扰动后大约30至50年或可能100年内达到平台，并且牧场不是永久的碳汇（Smith，2014）。
Identifying land uses and management practices that maintain or enhance soil carbon storage are important for sequestering carbon from the atmosphere and improving soil ecosystem services (Herrero et al., 2016). There is debate about how much additional carbon can be stored annually in soil, and for how long, following change in land use or management (Smith, 2014) and resolving this question is important. This is particularly relevant now following the aspirational goal established in the 4 per mille initiative (4p1000, 2017). In a paper titled:“Continuous soil carbon storage of old permanent pastures in Amazonia”, Stahl et al.(2017) purported to show increases in soil carbon when tropical forests are converted to grazed pasture of about 5.3 t C ha À1 year À1 through stock measurements across a chronosequence of sites. They state in the abstract:“... our results show that if sustainable management is applied in tropical pastures coming from deforestation... they can ensure a continuous C storage”, in the discussion:“This result supports the idea that certain ecosystems such as permanent pasture continuously accumulate soil carbon in the long-term (ie several decades).” and later in the conclusions:“Moreover, the humified C stored in the deeper soil layers is likely to provide unlimited C accumulation and conservation of C in the long-term.”(Italics added).Continuous and unlimited accumulation of soil carbon would certainly be of great interest to researchers, policy makers and the broader public as a large contributor to mitigating greenhouse gas emissions, particularly at rates as high as 5 t C ha À1 year À1. However, continuous and unlimited carbon accumulation is not supported by the author’s data or the general literature. Using measurements of soil carbon stocks in a chronosequence of sites converted from forest to pasture, they reported no change in soil carbon for the first 24 years followed by increases in soil carbon between 24 and 36 years at 5 t C ha À1 year À1. From these data, it is not reasonable to extrapolate these increases for 12 years as continuous or unlimited without further justification. In the broader literature, it has been widely observed that carbon reaches a plateau in roughly 30 to 50 years or perhaps 100 years after system perturbation as new equilibrium is reached, and that pastures are not perpetual sinks of carbon (Smith, 2014).