Coffee plantations can strongly sequester soil organic carbon at high altitudes in Brazil

Abstract

Context Soil organic carbon (SOC) affects all soil-based environmental services, and can be readily depleted upon cultivation. SOC concentrations are often higher in mountains than in lowlands due to lower temperatures slowing microbial activity and organic decomposition. However, the effects of altitudinal differences on SOC changes upon cultivation are mostly unknown. Aims We posed the question: when cultivated, are high-SOC mountain soils more likely to be depleted or are more stable under lower temperatures? Methods We assessed SOC concentrations and stocks (to a 40 cm depth) under comparable native forest and coffee (Coffea arabica L.) stands, both at two different altitudes (940 and 1260 m a.s.l.) along a mountain range in Brazil. The two soils were Inceptisols with similar 11° slope, and under native forests showed strong acidity, low fertility and cation exchange capacity. Key results Mean SOC concentrations under forests were relatively high, varying between 4.3% (0–5 cm depth) and 1.05% (20–40 cm depth) and were not significantly affected by altitude. The effects of cultivation varied with altitude: at 940 m, SOC concentrations decreased under coffee at the 0–5 cm depth, but increased below 10 cm depth at 1260 m, when compared to the native forest control. Conclusions SOC stocks under native forest and coffee stands were similar at 940 m, but the SOC stock under coffee stands at 1260 m increased by ca. 30 Mg ha−1. Implications These results are a promising indication that well-managed coffee stands can preserve or sequester SOC in higher altitudes, thus suggesting tropical mountain range soils are not highly susceptible to SOC losses upon conversion to perennial crops.