Planting Trees in Mexico for Monarch Butterfly Habitat

Planting Trees in Critical Monarch Butterfly Habitat

Every year, in the late spring and early summer months, when nature is reawakening after a long winter, something magical happens. From the Rocky Mountains to the Atlantic Ocean, and from southern Illinois to Canada, the air is abuzz with emergent eastern migratory monarch butterflies. 3-5 generations of monarchs are laid and hatched at these summer breeding grounds, each living for just a few weeks.

But the last generation, born in late summer to early fall, is different. They have a life span of about 9 months and undertake an epic journey, traveling up to 3,000 miles south in an annual migration that carries them to the welcoming montane oyamel fir and native pine forests of central Mexico. Believed to hold the spirits of the departed, their arrival coincides with La Dia de los Muertos, a holiday celebrated in Mexico to honor those who have passed. 

Oyamel firs and native pines are uniquely suited to provide the climate and shelter that eastern migratory monarchs need to rest after their long migration — and to survive the winter. In fact, the size of the eastern migratory population is measured by the number of hectares of oyamel fir and native pine forest they occupy. Here, they rest and conserve their energy until seasonal changes trigger a shorter migration back north to Texas. Upon arrival, they lay the eggs that will hatch into the first generation of a new monarch year.

Far more than an ephemeral harbinger of sunnier days and warmer temperatures, monarch butterflies are prolific pollinators. And they’re critical to the health of our planet. While feeding on the nectar that comprises their diet, they pollinate many types of wildflowers — providing an invaluable ecosystem service to forests and farmlands across their range. They also provide an important food source for birds, small animals and other insects.

Unfortunately, monarch populations have been dwindling due to loss of milkweed and nectar plants, deforestation and degradation of their overwintering grounds in California and Mexico, pesticide use, and climate change impacts like out-of-season storms, severe temperature drops, and heavy rainfall. All of these factors have manifested a steep decline, particularly during the last 20 years.

How Reforestation Can Help Monarch Butterflies

The Abies religiosa (Oyamel) tree, which has a lifespan of up to 300 years, helps form the traditional nesting site of the monarch butterfly. These unique trees are being lost due to a one-two punch of over harvesting and climate change.

Their strong wood is used to build train tracks — and during the establishment of the Mexican railroad system, logging and manufacturing sites were established, with profound effects. In addition to overharvesting impacts, the Abies religiosa can't tolerate temperatures above 25 degrees Celsius (77 degrees Fahrenheit). With steadily rising temperatures in their home range, the species has been forced to retreat further and further up mountainsides in search of cooler conditions — at a rate of 10 meters per year.

By planting oyamel and other native tree species to restore montane oyamel fir and pine forests, we can help protect vital monarch nesting grounds, restore landscapes that have been historically degraded, improve water filtration and watershed health, protect vital ecosystem services for nearby communities, and more.

Planting Trees for Monarch Butterflies

We are planting 500,000 trees to restore 650 hectares of land across several municipalities that are situated in and around the Monarch Butterfly Biosphere Reserve. The native tree species we're planting are Michoacan Pine, Pseudostrobus Pine, Cedro blanc, Encino, fresno, aile, and Oyamel. 

This project focuses on two types of restoration: converting deforested farmland back to native forest, and reforesting areas that have been severely degraded by clear cutting, forest fires, and bark beetle infestation. By working with local landowners, we're able to restore critical monarch habitat — much of which is mountainous, and therefore unsuitable for commercial or large-scale farming. 

As the trees grow and the land around the Monarch Reserve is restored, pressure on the remaining forest habitat will be reduced, and vital resting grounds will be restored. In addition to benefiting the monarchs, the growing trees will protect forest microclimates, prevent regional desertification, protect wildlife habitat, sequester carbon, reduce erosion and the likelihood of landslides, restore natural springs, and improve air quality.