Resumen

MONTANO, Noé Manuel et al. Carbon stocks and fluxes in arid and semiarid ecosystems of Mexico: Synthesis and prospects. Terra Latinoam [online]. 2016, vol.34, n.1, pp.39-59. ISSN 2395-8030.

The arid and semiarid ecosystems cover one third of world continental area and around 60% in Mexico, but their role in the global C cycle regulation is poorly known. The present paper analyzes data on C stocks and fluxes, as well as control factors of C dynamics in several arid and semiarid regions of Mexico. In these ecosystems, the net ecosystem productivity, soil respiration, litter fall, and litter decomposition are strongly affected by the total rainfall and its variability. Also, litter decomposition is affected by temperature and solar radiation. The main C pool in these ecosystems is the soil, containing 45% and 90% of total ecosystem carbon for desert-scrub and grassland, respectively. The semiarid regions have higher inorganic and organic C contents than the arid regions. However, soil organic carbon (SOC) is reduced by up to 50% because of land-use change, but this reduction may be mitigated by plant species, which form fertility and/or resources islands acting as a hotspot for conservation and transformation of SOC. Additionally, the soil biocrusts play an important role in the SOC accumulation, because it responds quickly to humidity pulses and therefore nutrients are released from organic compounds. Finally, SOC availability strongly affects microbial activity, which in turn controls soil nutrient availability and nutrient stoichiometry ratios linked to soil fertility. We conclude that the information of C stocks and fluxes in semiarid and arid ecosystems of Mexico is scarce and fragmented, because the majority of the studies are focused in SOC quantification in the upper 30 cm soil layer, and soil inorganic C is often not measured. For this reason, it is urgent and necessary to standardize methods and intensify the research on soil C dynamics in these ecosystems, integrating different spatial-temporal scales.

Palabras llave : biocrusts; mexican deserts; fertility islands; desert-scrubs; grassland.