The urgent need for reforestation of hills near Mexico City

A coniferous tree plantation is being formed on the lower slopes of Ajusco, the 3,930 m (12,894 ft) volcanic peak that overlooks the southern part of Mexico City. After decades of uncontrolled land clearance, local farmers are replanting 800,000 trees as part of a sustainable project which will ensure them a reliable income for years to come. Mexico’s National Forest Commission estimates that mature coniferous plantations are highly profitable, and should repay farmers a 500% return on their investment. Individual trees have to be at least 8 years old before they can be harvested.

Three species of conifers are being planted: the Sacred Fir (oyamel), Douglas Fir and Mexican White Pine (ayacahuite). At present, only about one-third of Christmas trees sold in Mexico are natural trees, with 60% of these having to be imported from as far away as Canada.

The project will not only increase farmers’ incomes, it will also reduce soil erosion, increase carbon storage, and bring hydrological benefits. Mexico City has seriously depleted its aquifers – see Why are some parts of Mexico City sinking into the old lakebed? Reforesting the hills surrounding the city means more water will be retained in the soil, and less will runoff into the city’s already-stressed network of storm drains.

Ajusco is not the only volcanic peak near Mexico City where deforestation has become a major issue. In August 2011, National Water Commission (Conagua) officials blamed serious flooding in the Rayón municipality of the State of México on the uncontrolled logging of the lower slopes of the Nevada de Toluca volcano.

The lack of protective forest cover meant that heavy rain caused the River Santiaguito to burst its banks and flood homes in the community of San Juan La Isla. The situation would have been far worse if Conagua had not ordered the dredging of 12,000 cubic meters along a 4 km stretch of the river bed in 2009. Following the 2011 floods, Conagua reiterated the need for more reforestation and called for stricter land use controls to prevent similar problems in the future.