Carbon storage in mountain cloud forest communities, Jalpan de Serra, Querétaro, México

Mountain cloud forests (MCF) are vulnerable ecosystems that harbor considerable biodiversity and are essential carbon regulators. However, information is scarce on the carbon storage potential and its patterns of variability across the conservation gradient in these forests. This study determined the carbon storage potential, the contribution of different pools, and their relationship with the degree of forest and soil conservation.

The organic carbon storage of the communities ranged from 145.9 to 279 Mg C ha^-1. Soil was the primary pool (68.08-198.1 Mg C ha^-1), followed by above-ground biomass (42.87 - 116.74 Mg C ha^-1), while the contribution of litter and roots was less. The contribution of above-ground biomass to the carbon stock was low due to the level of timber and fuelwood extraction present in these communities. The high carbon storage potential of the soil pool is determined by the presence of the O horizon, with a thickness of 8-10 cm, forming mull-type humus and a deep organo-mineral surface horizon with a high carbon content > 10 g kg^-1, and with varying degrees of humification. The formation of clay-humus complexes maintains carbon stabilization and the formation of deep surface horizons (between 20 and 38 cm deep).

The results show that the carbon sequestration potential of the MCF is found in the soil associated with the organic horizons that develop at the surface and the presence of deep A horizons with high carbon content. The conservation of these layers, despite forest management, reflected in the aerial biomass, demonstrates the resilience of the soil due to carbon stabilization, attributed to the composition of resistant organic compounds and the formation of clay-humus complexes, which reduce the impact of degradation from erosion. This indicates that the conditions of the MCF still sustain the ecological and biogeochemical processes that support carbon sequestration and are regulated by the conservation policies of the Sierra Gorda Biosphere Reserve, Querétaro, Mexico.