Carbon cycling at high elevations: temporal and spatial patterns of soil respiration across a tropical alpine elevation gradient
Abstract
The alpine region of northern part of the Tropical Andes have a wet climate and soils with extremely high contents of organic matter. Temperatures in the Andes Cordillera are predicted to increase by 4 °C at the end of this century affecting the dynamics of tightly coupled biogeochemical cycles. One of the main expected effects of air and soil warming are increases in soil respiration rates. Understanding how soil respiration is affected by changes in temperature is difficult due the inherent changes in the physical setting and climate along elevation gradients. In this study, we aimed to study the effects of temperature and elevation on the dynamics of CO2 effluxes from soils from two steep elevational gradients in the northern Andes at the Nevados and Chingaza National Parks in Colombia. We measured soil CO2 fluxes and soil carbon dynamics 3 times a year from 2013 to 2018 across two slopes with contrasting climatic conditions in twelve sites ranging from the treeline at 2.900 to the upper vegetation limit at 4.400 m in elevation.
Soil respiration rates were low with individual values rarely exceeding 3 µmol CO2 m-2 s-1. Sites located Dryer sites had a lower respiration rate than sites at similar elevations in the wetter site. Sites at lower elevations had higher soil respiration rates (1.7 µmol CO2 m-2 s-1) than sites at higher elevations (0.6 µmol CO2 m-2 s-1). We observed a positive correlation between dry periods and soil CO2 efflux with higher fluxes in dryer months. Particularly, soil carbon content was higher at the wetter sites (22%) when compared to the dryer sites (5%). Aboveground biomass and litter production was similar between the two sites indicating that under the soil organic matter accumulated in the soil is the product of reduced decomposition at the wettest site. Our results suggest that soil temperature, reduced soil moisture and shrub encroachment at alpine elevations will have a positive influence on soil CO2 efflux rate increasing CO2 emissions.- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.B21H2425B
- Keywords:
-
- 0414 Biogeochemical cycles;
- processes;
- and modeling;
- BIOGEOSCIENCESDE: 0428 Carbon cycling;
- BIOGEOSCIENCESDE: 0454 Isotopic composition and chemistry;
- BIOGEOSCIENCESDE: 1615 Biogeochemical cycles;
- processes;
- and modeling;
- GLOBAL CHANGE