Post by our summer intern, Saige Patti!
Monarch populations have dropped by 90% since the 1990’s.
In the past, the decline in monarch populations has been largely correlated with loss of common milkweed – the only plant on which monarchs lay their larvae. Milkweed decline has occurred mostly in agricultural crops. The plants can’t survive contact with the chemical glyphosate from Monsanto’s Roundup pesticide. Agricultural milkweeds in the Midwest are significant: they have 4 times more monarch eggs than non-agricultural milkweeds, and in 2012 an 81% decline of agricultural milkweeds correlated with a decline 81% monarch production decline.
Unfortunately, declining numbers of milkweed plants are not the only thing affecting the monarchs.
A new threat has emerged: our beloved avocados.
While planting more milkweed and avoiding Roundup Ready GM crops are key steps to restoring habitat for monarch butterflies in North America, an increase in demand for avocados may annihilate crucial portions of their habitat in Mexico.
Popularity of avocados has surged in North America in recent years. With avocado being used for guacamole, sandwiches, smoothies, salads, pastas, and even desserts, it’s no wonder the versatile fruit is in demand. The market is also starting to expand globally; distributor Mission Produce Inc. is aiming to find ways of increasing avocado sales in China, which would greatly increase demand if it became popular.
The avocado business in Mexico is lucrative. With prices rising, it’s a good deal for land-owners to clear cut the forest and start growing crops.
These are the trees on which monarchs spend the winter. When these forests were abundant, monarchs would overwinter in expansive areas of the sacred fir trees. Now, they cluster in a few groups of trees in the Monarch Butterfly Biosphere Reserve.
Oyamel forests are Mexico’s most endangered forest type with only 2% of the original forest remaining.
Monarchs are adapted to a delicate microclimate created by these forests, which changes when the forest is thinned or the perimeter is eliminated.
What is left of Oyamel forests is crucial to the survival of the monarch species.
Most of the butterflies overwinter in the Mexican State of Michoacán, where 20,000 hectares a year are converted for agricultural use, according to the attorney general's office for environmental protection. Avocados account for 30-40% of annual forest loss.
Deforestation as a result of avocado farming further adds to the effects climate change is already having on the forests. A 2012 study predicted that a changing climate could account for a 69.2%, decrease of sacred fir trees, and that increasing temperatures might require people to move trees 275m higher to cooler temperatures, and out of the Monarch Butterfly Biosphere Reserve by the end of the century. Additionally, trees are felled to create single-use crates in which the avocadoes are shipped.
Mario Tapia Vargas, a researcher at Mexico’s National Institute for Forestry, Farming and Fisheries Research, says that even where deforestation has not yet happened, there are areas with avocados growing in the understory. This alters the natural forest ecosystem and it’s ability to support wildlife. Tapia Vargas says it won’t be long before the forest around these crop trees are cut down as well.
With monarch populations already headed for extinction in the next 20 years based on milkweed decline, the effect of avocado crops would contribute even further to eliminating vast numbers of monarchs. This is dangerous, since small populations are more vulnerable to sudden environmental changes, which are increasing with the effects of climate change effects.
Additional loss of monarchs as a result of future avocado crops could quickly lead to monarch extinction.
Is Anyone Taking Action?
In Carpinteros, they decided to stop cutting trees for profit on their communally held land. The community had already become economically stable as a result of avocado farms, and they knew that the benefit the forests provided by holding and filtering water through the soil to their crops outweighed the income they could get from expanding avocado crops. Besides eliminating monarch habitat, change in land use for avocado crops results in an extra 0.5 tons of carbon per hectare per year, and also reduces filtered water for community. This forest-filtered water plays a key role in soil conservation, basin water balance, water supply for many uses.
The Balearic Provincial Association of Companies of Maritime Activities has a reforestation program that has planted more than 500,000 pines in Michoacán since 2010. In 2017, they plan on planting 280,000 additional trees, and in 2018 planting 320,000 additional trees.
In Zitacuaro, the city used to give away avocado trees for free to encourage farmers to grow the lucrative crops. They stopped giving out the trees to interested farmers four years ago to discourage deforestation.
As a consumer, you might choose to avoid buying avocados sourced from Mexico, but this could only make a significant difference as part of a massive boycott, and would likely have you purchasing California avocados. Although a decrease in demand for Mexican avocados could potentially relieve some deforestation, the water-intensive crop does not aid the drought issue in California.
In the midst of news about illegal avocado plantings contributing to deforestation, government organizations such as Secretariat of the Environment and Natural Resources (SEMARNAT), and the National Institute of Forestry, Agriculture and Livestock Research (INIFAP) condemned the practice. It is unclear what is being done to prevent illegal deforestation.
Although people are becoming aware of this problem and beginning to take action, increased action and stronger policy is likely needed unless we want to see the Monarch disappear in the next few decades.