To Make it Rain, Plant More Coffee Trees
Coffee-growing regions are quickly becoming hotter and drier while at the same time losing substantial tree cover. Trees and forests create and maintain their ideal conditions by producing rainfall, and coffee excels as a crop of economic significance that thrives as part of a forest-like system.
Coffee farms cover 11 million hectares of ecologically sensitive land worldwide. Many of these farms are the last bastion of standing trees in landscapes that would otherwise be deforested and dehydrated. As part of an integrated agroforestry system, coffee trees are the key to preserving and expanding tree cover and maintaining and repairing regional water cycles.
Contrary to commodity crops like corn and soy, which are ecologically unfit for the fields where they're planted, coffee is the ideal crop for most of the ecosystems where it grows. As an understory species, coffee trees prefer a shade story above them. They grow most vibrantly within a web of companion plants among their drooping branches adorned with waxy emerald leaves and bright red cherries. Coffee trees offer the unique possibility of planting a productive crop in a forest-like system of complimentary trees of multifunctional use like hardwoods, nitrogen fixers, fruits, and nuts.
Grown within an integrated agroforestry system, coffee farmers can produce abundant high-quality yields while simultaneously regenerating soil, water cycles, and overall ecosystem function.
Emerald green coffee trees thrive in the understory of a diversity of shade trees.
The problem is most coffee farms are far from this ideal. The few successfully implementing integrated systems are relatively unknown compared to the standard coffee industry narratives dominated by pessimism and non-solutions.
Lamenting the change in climate and particularly the historic rain patterns that once came like clockwork, seems to be a part of every coffee farming conversation. Typically this is written off as the effects of global climate change. But with a closer look, we can see more than a complex external force victimizing coffee farmers. Many of the adverse weather conditions farmers face result from the loss of tree cover and biodiversity at the local level.
In several coffee-growing countries, coffee trees represent a large share of the remaining tree cover. Between 1970 and 1990, approximately 50% of the shade trees associated with coffee farms in Latin America were lost. Globally, coffee farms have lost 20% of their shade trees since the mid-1990s, and countries like Costa Rica and Colombia lost between 50% and 60% of shade tree cover. This is a consequence of intensified production, where coffee trees grow in full sun and bare soil. The loss of shade is accompanied by the increased use of synthetic fertilizers and pesticides, further disturbing the ecology of these areas.
The textbook description of the water cycle presents the ocean as the primary source of condensed atmospheric moisture and ultimately falls as rain. Missing is the role of trees as veritable water fountains, pulling water up from the soil with their extensive root systems and releasing that moisture into the atmosphere through the microscopic pores of their leaves. This arboreal version of sweating is the process known as transpiration. A single tree can transpire hundreds of liters of water per day, and a forest, with its extensive, layered leaf surface area, can transpire an amount of moisture equal to or exceeding that of a large body of water.
Another step is required to turn the transpired water into rainfall, and trees are once again the benefactors making it all happen.
Trees transpire water into the atmosphere to produce precipitation and ice particles that take shape in the clouds. Not long ago, the prevailing belief was that small mineral particles served as the nuclei to catalyze ice particle formation. However, we now know that microbes, originating from the forests below, catalyze ice particle formation and trigger precipitation at higher temperatures than inert material like minerals. In other words, clouds don't have to be as cold for ice nucleation, and rainfall can occur in a broader range of conditions.
Approximately 40% of precipitation over land originates from the evaporation and transpiration of water from plants.
Simply put, trees create rainfall. In one of the more impressive feats of low-tech terraforming, Willie Smits reforested a 2,000-hectare area of clearcut Borneo forest using agroforestry and six years later documented a 12% increase in cloud cover with a 25% increase in rainfall.
Forests don't simply grow in moist areas; they create and maintain the conditions in which they grow by producing rainfall and shortening the length of the dry season.
When trees are removed from the landscape, the rainy season becomes sporadic, and less water is available for evaporation and transpiration, effectively turning off the source of rainfall.
A key theme of the theory described above is the forest structure, not just individual trees. The action of trees seeding the rain through transpiration and microbial ice nucleation is the product of a more complex forest structure and greater leaf surface area — not monocrop tree plantations.
While coffee has been planted as a monocrop with increasing furor in the past few decades, it is one of the only crops of economic significance that grows as part of a system that mimics the natural forest structure and dynamics of its tropical environs. The benefits of growing coffee in an agroforestry system are vast and the solution to coffee farmers' most pressing issues.
