Spectroscopic Assessment of Soil Organic Matter Stability in Peatlands From the High Andes.

Peatlands constitute around 2 % of the global landmass and are home to many specialized organisms that are found nowhere else. They are valuable for their function as carbon sinks, water conservation and filtering, flood control, and as a recreational landscape. In the Central and Southern Andes peatlands a.k.a. bofedales are a source of good quality pastures for wild and domestic South American camelids. Bofedales are threatened by climate change, which is altering the water input from glacier snowmelt and increasing the variability of rainfall. A related thread is the pressure exerted by Andean peasants to convert them into cropping and pasturelands. In the present study whole soil samples were analyzed using the Laser-Induced Fluorescence (LIF) and Electron Paramagnetic Resonance (EPR) spectroscopy to assess the soil organic matter stability of both well preserved and degraded bofedales in the high Andes. The results obtained by both techniques were compared and they have been shown to be reliable indicators of increases or reductions on the stability of the organic matter, depending on the conservation status of the bofedales. The preserved bofedales (water logged) showed a more dynamic soil organic matter due to higher labile carbon input, compared to degraded (drier) ones. It is well known that decomposition rate is slower in water logged peatlands. The linear correlation between LIF and EPR results was 88% and it clearly demonstrated that our technique for evaluating soil humification was efficient. Also, a portable LIF system was used and compared with a bench LIF system, yielding a 98% linear correlation, proving to be an affordable option for the assessment of soil humification dynamics in situ. This assessment is of outmost importance in agro ecosystems contributing with emission or capture of greenhouse gases under variable climatic conditions.