Soil Carbon Stocks under Amazonian Forest: Distribution in the Soil Fractions and Vulnerability to Emission

• 作者: Euler Melo Nogueira Flávio Jesus Luiz?o Jean Dalmo de Oliveira Marques Max Sarrazin Philip Martin Fearnside Wenceslau Geraldes Teixeira
• 来源期刊: 林学期刊(英文)
• 学科: 医学
• 关键词: FRACTIONATION of CARBON CARBON Stocks Soil Physics Global WARMING AMAZON RAINFOREST Brazil
• 年，卷（期）: 2017,（2）
• 页码范围: 121-142
• 页数: 22页
• 分类号: R73

摘要

Transformations of natural ecosystems in tropical regions, which are usually covered by high-biomass forests, contribute to increased atmospheric CO2. Much of the carbon in forest ecosystems is stored in the soil. This study estimates soil carbon stock in a dense forest in central Amazonia from sets of soil samples collected in three topographic positions (plateau, slope and valley bottom). Soil organic matter (SOM) was fractionated by density and particle size, thus obtaining the free light fraction (FLF), intra-aggregated light fraction (IALF), sand fraction (F-sand), clay fraction (F-clay) and silt fraction (F-silt). Soil organic carbon (SOC) stocks on the plateaus (Oxisol), slopes (Ultisol) and valley bottoms (Spodosol) were 98.4 ± 7.8 Mg·ha-1, 72.6 ± 5.4 Mg·ha-1 and 81.4 ± 8.9 Mg·ha-1, respectively. Distribution of carbon in soil fractions was: 112.6 ± 15 Mg·ha-1 (FLF), 2.5 ± 0 Mg·ha-1 (ILAF), 40.5 ± 1.5 Mg·ha-1 (F-silt), 68.5 ± 4.2 Mg·ha-1 (F-clay) and 28.3 ± 1.4 Mg·ha-1 (F-sand), totaling 252.4 ± 22.1 Mg·ha-1 of carbon. Carbon is largely in labile form and near the soil surface, making it liable to release from deforestation or from climate change. Spodosols are more susceptible to soil carbon losses, demonstrating the need to preserve forested areas close to Amazonian rivers and streams.