Soil carbon stocks across tropical forests of Panama regulated by base cation effects on fine roots
Soil carbon stocks across tropical forests of Panama regulated by base cation effects on fine roots
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DOI：
10.1007/s10533-017-0416-8
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发表时间：
2018-01-01
期刊：
影响因子：
4
通讯作者：
Turner, Benjamin L.
中科院分区：
文献类型：
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作者：
Cusack, Daniela F.;Markesteijn, Lars;Turner, Benjamin L.
热带森林是地球上碳储量最丰富的生态系统，占全球陆地碳储量的25-40%。虽然热带森林地上生物量的大规模量化最近有所改善，但土壤C动态仍然是地球系统模型中最大的不确定性来源之一，这抑制了我们预测未来气候的能力。在全球范围内，土壤质地和气候可以预测土壤碳储量变化的30%，因此生态系统模型通常使用地上植物生长的措施来预测土壤碳。然而，这种方法可能会低估热带土壤碳储量，并已被证明是不准确的，与数据丰富的北方生态系统的土壤碳数据相比。通过量化土壤有机碳储量为1米深的48个潮湿的热带森林地块的降雨和土壤肥力的梯度在巴拿马，我们表明，土壤碳不相关的模型中使用的常见的预测因子，如植物生物量或凋落物生产。相反，一个结构方程模型，包括盐基阳离子，土壤粘粒含量，降雨作为外源因素和根生物量作为内源因素预测近50%的热带土壤碳储量的变化，表明热带土壤碳储量的盐基阳离子的可用性强的间接影响。在碳循环模型中包括土壤盐基阳离子，从而强调养分，根生物量和土壤碳储量之间的机械联系，将改善热带森林气候-土壤反馈的预测。
Tropical forests are the most carbon (C)-rich ecosystems on Earth, containing 25-40% of global terrestrial C stocks. While large-scale quantification of aboveground biomass in tropical forests has improved recently, soil C dynamics remain one of the largest sources of uncertainty in Earth system models, which inhibits our ability to predict future climate. Globally, soil texture and climate predict 30% of the variation in soil C stocks, so ecosystem models often predict soil C using measures of aboveground plant growth. However, this approach can underestimate tropical soil C stocks, and has proven inaccurate when compared with data for soil C in data-rich northern ecosystems. By quantifying soil organic C stocks to 1 m depth for 48 humid tropical forest plots across gradients of rainfall and soil fertility in Panama, we show that soil C does not correlate with common predictors used in models, such as plant biomass or litter production. Instead, a structural equation model including base cations, soil clay content, and rainfall as exogenous factors and root biomass as an endogenous factor predicted nearly 50% of the variation in tropical soil C stocks, indicating a strong indirect effect of base cation availability on tropical soil C storage. Including soil base cations in C cycle models, and thus emphasizing mechanistic links among nutrients, root biomass, and soil C stocks, will improve prediction of climate-soil feedbacks in tropical forests.