Soil organic carbon pool under native tree plantations in the Caribbean lowlands of Costa Rica

We evaluated the soil organic carbon (SOC) pool and selected physico-chemical soil variables in a plantation with native tree species established in a degraded pasture of the Caribbean lowlands of Costa Rica. Studies on the rate and accumulation of aboveground biomass and C have been conducted in native tree plantations of Costa Rica. However, more studies on the SOC pool are needed since only few works provide information on the subject. The tree plantation was established in 1991 on a 2.6 ha. degraded pasture (Ischaemum sp.) Four species were selected: Vochysia guatemalensis Smith, Calophyllum brasiliense Cambess, Stryphnodendron excelsum Poeppig et Endl. and Hieronyma alchorneoides Allemao. Average SOC concentration ranged from 44.9 to 55.2 g kg−1 (0–10 cm), and decreased with depth up to 12.7–16.8 g kg−1 (40–50 cm). The highest SOC pool was measured under H. alchorneoides and V. guatemalensis, i.e. 131.9 and 119.2 Mg C ha−1, respectively, whereas in the pasture it was 115.6 Mg C ha−1. The SOC pool has not changed significantly under the tree species evaluated 14 years after establishment. A multivariate ordination technique named between-within class principal component analysis was used to determine the factors and trend that explain the variability in the data. The effect of vegetation in the SOC and selected soil variables measured in this study was only detected for H. alchorneoides. The information presented herein about the depth distribution of the SOC fraction improves our knowledge for further developing prediction models.