When visiting the Colombian farm owned by Duver Rojas, you are met by a green mountainous landscape. Here, every part of the mountainside is covered with plants and trees. Besides from the obvious coffee trees, you will find Avocado trees and different fruit trees, among others. These trees are part of this farm’s biodiversity, and each tree has a specific purpose, which I will describe later in the blog post. What they have in common, is that they function as shade trees.
We asked Assistant Professor at Copenhagen University, Aske Bosselmann, what makes a shade tree?
»Basically, a shade tree is a tree that grows higher than a coffee tree, and creates what we call a canopy layer, a tree crown above the coffee providing shadow. A shade tree could be a fruit tree which may not grow much higher than 5-7 meters, and it could be a forest tree growing up to 30 meters high, and it could be everything in between.
Minimizing the amount of light, causes the coffee tree’s flower induction to drop. Fewer flowers will mean fewer fruits. This means that the plant has more energy in its system that can go straight to the fruits.
If the plants are exposed to full sun the fruits will ripen much faster – and often too fast. The fruit will look mature and ripe from the outside, but the actual berry is not fully developed. This will lower the quality of the coffee. Providing shadow instead, will mean the fruit can develop even longer on the tree and become fully matured.
In some coffee plantations there are shade trees growing extremely fast that can handle to have their branches cut off. This creates a high inflow of light during the period of blossoming. During the fruit development, the branches have grown out again, creating shadow during the fruit maturation. This method gives more flowers, which gives more fruits and then there’ll be shadow at the time of ripening giving a fully developed berry. This kind of management require a skilled farmer, sufficient labor and the right shade trees. «
Thanks to Aske for giving us a better understanding, of how important shade trees can be to grow good coffee. Duver Rojas talks about his experience with shadow trees:
»There is this idea floating around at the moment, where people argue that you should remove your shade trees from your fields in order to stress your coffee trees into producing more. But I believe that idea is just based on theoretical knowledge.
I’ve been growing coffee for many years, and I have experienced first-hand the difference shade makes. All the trees I have that spent most of their time in shade, produce both better quality and have a steadier yield of cherries. It seems that some varieties of trees just need a little bit of time to adapt to an environment with more shade. As time has gone by, I have experienced that all the different varieties I plant, the trees in the shades will eventually grow cherries with thicker mucilage and better cupping scores. «
In Colombia, the farmers have a great knowledge about shade trees and often go with fruit trees which give a good yield they can enjoy during harvest. Mostly, there is a higher purpose with the shade tree than to just provide shadow. This can be a crop, timber or storage of carbon and nitrogen etc. In the following Duver will explain what purpose his shade trees have:
»Needless to say, I love shade. But shade can do more than help with my cupping scores. I choose to plant trees that serve purposes beyond that. Some trees help retain water in the soil, others keep away animals and insects from my coffee and other crops. But the most important thing about the shade trees I plant, is that they should all provide organic material for the soil. A farm with shade gives oxygen to the world, nitrogen and organic material to the soil and it keeps its workers cool and happy. A farm without shade has no life. I have around 20 different shade trees. About 12 of them is provided by the rainforest and the rest I have planted with specific purposes. I will show you some of them. «
Shortly, we will go through Duver’s shade trees and their different functions. But first, a quick walk through one of nature’s fascinating processes; one of the good things about having a coffee farm close to nature’s system, is, that a lot of things happen on its own, including fertilising the coffee. Some trees have the ability to pull nitrogen out of the soil and air and absorb it. Nitrogen absorbed in trees can be recovered as a fertilizer to your coffee by composting leaves and branches to humus. A process which happens in most of Duver’s shade trees mentioned below.
This tree has a very distinct look; small, drop-shaped leaves placed together in elegant fans in a bright green colour. When the leaves drop from the tree, the above described process occur, and the leaves are composted, leaving its nutrients to be absorbed by the coffee trees. The leaves drop two to three times a year right when the coffee is blossoming, providing a natural fertiliser just when the coffee needs it.
From the delicate branches, long bean-shaped fruits are hanging. Some call this tree a Drumstick Tree because of the fruits’ long shape. The fruit, called Vana by the locals, is used for feeding the horses on Duver’s farm.
A bush-like tree with long spiked leaves growing from the multi-stemmed shrub. This small tree growing about seven meters tall is originating from the fig family, and fruiting occurs throughout the year. The very sweet fruit is only used for a special cake around Christmas, the rest of the year they let the fruits drop which act as a natural fertiliser.
Better known as an Avocado tree, this like the Moringa tree, provides nitrogen to the coffee trees when its leaves drop to the ground.
Furthermore, Duver uses the ripe avocados to eat and the ones that drop to the ground nourishes and keeps the microorganisms in the soil going.
You may know this pear-shaped green fruit with bright red pulp, the Guava. Other than provide shadow for the coffee trees it also provides food for the animals and the people living on the farm.
The deep orange colour on this unique tree is standing out among all the green nuances on the farm. When the orange leaves fall to the ground they are decomposed, providing nitrogen that is absorbed by the coffee trees. It also serves as a bug resistant, as certain bugs called Cucarron loves to eat the leaves. If it couldn’t eat these leaves it would attack the coffee trees instead.
A tall tropical-looking tree, with thick wavy leaves in a deep green colour. It has long bean-like fruits in a lighter green that squirrels love to eat. This is a good thing, as the squirrels then won’t eat the Yucca.
Like many of the above-mentioned trees, the Guamo tree also provides a natural fertiliser, nitrogen, to the coffee trees, besides from providing shade. In addition, the tree retains water.
Imagine that tree which always comes to live in fairy tales. This would be one of those. With meter long lianas dangling from the large boughs with fruits in between. Fruits, the bats love to eat, keeping them away from the peaches.
Along with the above mentioned trees the Higueron will also provide nitrogen for the soil and the coffee that grows underneath it. This tree in particular seems to obtain a rather high amount of nitrogen compared to other trees.