Soil carbon reservoirs at high-altitude ecosystems in the andean plateau

Mountain landscapes are among the most fragile landscapes on earth and are sensitive to both anthropogenic and natural forces. The Andean plateau is one of the largest in the world measuring more than 7500 km. Mountain environments are strongly influenced by changes in temperature and precipitation. For this reason, they are good indicators of the impacts of the climate change. Growing interest in the potential for mountain soils to provide a sink for atmospheric C has prompted studies regarding the effects of management on the nature, amount, and nature and transfer of soil organic carbon (OC). It is crucial to gain knowledge about the different C pools and functional groups in order to establish the rate of soil organic matter biodegradation. The cold and wet climate and the low atmospheric pressure favor organic matter accumulation in the soil. Organic matter decomposes very slowly in the moist, cool conditions that result from high elevation, frequent cloudiness, fog interception, and rainfall. Organic matter content increases with the altitude likely a result of its slow decomposition due to not only lower temperatures but also lower soil pH. Several researchers have found that around 40-60% of the soil OC exist within the top 20-cm layer and the content changes mostly between 4 and 10% in high-altitude grasslands. This is much more than organic matter content in agricultural soils. The high C/N ratio in the Andean highlands (between 12 and 18) could indicate that humification is likely more intense than mineralization processes. Unexpectedly, high recalcitrant (RC) index found in the northern Bolivian puna suggests a high storage of recalcitrant OC. High storage of RC is advantageous to the preservation or stabilization of soil mineral particles and the long-term carbon (C) sequestration. However, the increase of the temperature due to the global change could seriously affect these essential C reservoirs. Knowledge on the CO fluxes and its implications to the global increase of CO levels in the atmosphere is extremely important and adds to our knowledge about the relevance of long-term C stocks in the Andean plateau. In many cases, ecosystems in the central and southern Andean highlands are degraded as a consequence of anthropogenic activities such as the change in soil use and unsuitable water management in addition to excessive cattle grazing.