Altitudinal Pattern of Soil Organic Carbon and Nutrients in a Tropical Forest in Puerto Rico
| Authors: | Dingfang Chen, Mei Yu, Grizelle Gonzalez, Qiong Gao |
| Year: | 2023 |
| Type: | Book Chapter |
| Station: | International Institute of Tropical Forestry |
| DOI: | https://doi.org/10.1007/978-3-031-22848-3_12 |
| Source: | Neotropical Gradients and Their Analysis |
Abstract
Tropical forests have the highest net primary productivity and soil carbon flux yet bear large uncertainties in being a carbon sink or source under changes in climate. To better understand the responses of tropical soil to climate change, we analyzed the distribution patterns of soil organic carbon and nutrients along an altitudinal gradient in the Luquillo Experimental Forest, northeastern Puerto Rico, which provides a natural approach to study how the altered temperature and precipitation impact tropical soil carbon processes. We collected soil samples at two depths (0–15 cm and 15–30 cm) from 15 plots ranging from 300 to 1000 m in elevation and analyzed the soil physicochemical properties. Soil physical properties showed significant altitudinal pattern with clay content decreasing but water content increasing with elevation. The clay content in sublayer (70% in average) was significantly (p < 0.01) higher than that in the top layer (53%). Both soil carbon content and C:N ratio significantly increase with the elevation and are significantly influenced by the vegetation. While soil carbon, nitrogen, and phosphorus increase with the elevation, mostly owing to a low decomposition rate and low uptake by the less-productive elfin forest at the top with low temperature and often saturated soil, K, Ca, and Mg decrease attributing largely to rainfall-driven leaching. Elfin forest has higher C, N, and P than the palo colorado forest, and palo colorado forest has greater C and N than the tabonuco forest. The multivariate ANOVA showed significant explanation by elevation and vegetation on variations of both macronutrients and micronutrients. The projected warming and altered rainfall regimes might bring significant effects on C redistribution in tropical soils.