Where the Andes meet the Amazon, you will find one of the earth’s richest and most important biomes. Its role has been overlooked in our efforts to mitigate climate change.
If there is an ecosystem that captures my imagination, it is the cloud forests, or perhaps better called, “the forests of the clouds”. Walking underneath their damp and dark canopy brimming with colourful orchids and bromeliads you enter an enchanted world, as if at any minute a green dwarf could surprise you from behind a rock. Cloud forests’ extraordinary colours shine in shimmering shades of fluorescent hot pinks, dark blues, bright purples, and chilling reds. There, hummingbirds seem to be more abundant than bees, sometimes buzzing so close as if wanting to rest on your head. And best of all, there are no mosquitoes! After 40 years working in tropical forests, I chose them as my favorite type. However, these forests are facing enormous challenges, and not many are aware of their importance, nor have experienced their magic. Below is an account of what those cloud forests are, and why they matter, in the face of our changing world.
For many the Amazon brings to mind a vast extension of a uniform forest, a green carpet interrupted by wide meandering rivers. But at a closer look, besides its typical tall rainforests, the Amazon is a mixture of many ecosystems, including mountain forests, savannas, dry forests, single-species forests, wetlands, and many other types of vegetation. Hence, it is a mistake to treat the Amazon as a single ecological unit.
Among all, one of the most distinctive and perhaps most underappreciated forest types are those that thrive in steep mountains, closer to the snowy peaks of the Andes, the Amazonian cloud forests. Running along eastern Colombia, Ecuador, Peru, and Bolivia, those forests are ecologically very different. Fragile, endangered, and extremely biodiverse, they are only recently becoming understood and appreciated. Our efforts to mitigate climate change and prevent further major losses of biodiversity require paying particular attention to them.
Starting at 4000 metres above sea level, cloud forest trees carry a heavy load of epiphytes that, besides giving them a peculiar look, “harvest” water from the clouds. Clouds that originated thousands of kilometres away, in the Atlantic Ocean, and after several iterations of evaporation, condensation and precipitation, finally hit the giant forested wall that is the eastern side of the Andes mountains. It is from there that the waters start their return to the ocean, flowing down the Andes through myriads of rivers converging in the mighty Amazon River.
Several studies have looked at the properties and function of the cloud forests, and water retention is a critical one. The vegetation not only acts like an active sponge, but also regulates the flow of water to defined courses. They capture more than 60 per cent of the water in the atmosphere, and without this capacity there would not only be massive tree mortality at lower elevations, but in periods when rains are abundant, severe erosion, landslides, uncontrollable floods, and a major ecological and human disaster would ensue.
Cloud forests are also an important carbon sink. Considering how slow the decay of organic matter is in these high-elevation forests, it is estimated that their dead biomass matches that of the living forests. Andean forests rank as one of the densest carbon deposits among all Amazonian ecosystems, something that is changing as climate warms.
The cloud forests’ plant and animal species are quite unique and densely packed in narrow elevational ranges. You can find a complete replacement of species assemblages in narrow horizontal strips, as if each was living in a different floor of a building. Hence, viewing a mountain from top to bottom, an extraordinary biodiversity piles up. In the Kosñipata valley in southeastern Peru, for example, close to one thousand species of birds have been registered from the top of the mountain to its lower ranges. That is one tenth of all bird species on the planet.
These Andean forests provide a refuge and the only option for species to avoid extinction. As the climate is warming up, many life forms, including trees, need to “move up” to their optimal thermal range, i.e., to higher and colder elevations. Researchers have been measuring the rate of upward movement of different species for the last several decades and the results are perplexing. Trees, for example, are moving up at a rate of 2.5 metres a year and modelling shows that they will move up to 9 metres a year by the end of the century. Some species of beetles have already moved up at a rate of 40 metres a year. Without an elevation gradient in an uninterrupted forest, there is no escape in the face of a warming climate. These forests are also home to spectacled bears, mountain tapirs, woolly monkeys, and many other flagship and keystone species. Other studies have documented the importance of these species and the differential impacts in tree recruitment in their absence.
Because of the introduction of cattle from the old world, the upper limit of these forests today, the tree line, is in most places almost one thousand metres in elevation below where it was 500 years ago. Restoration of that vegetation is of most critical importance if we want to allow species to adapt to our changing world.
Burning of the upper elevation grasslands and the opening of new previously forested areas for both animal husbandry and expansion of the agricultural frontier, are by far the main threat to these Andean forests. Suitable land for agriculture is largely scarce and the booming of illegal crops has further complicated the scenario. Add to it mining, road development, and a proliferation of commercial crops at the lower end of these mountains. Altogether these make cloud forests perhaps the most endangered forest type in the Amazon.
But there is progress and hope. Iconic protected areas like Madidi National Park in Bolivia, Manu National Park in Peru, and scores of other protected areas along the Andes Amazon range are effectively protecting large swaths of forests, even entire watersheds. But assuring the connectivity of these areas is critical and remains a challenge. Andean nations and most notably, local communities, are making great efforts to protect as much forest as possible. And more importantly, there is a growing sense of pride and ownership in the cultural values of Andean Amazonian ecosystems for local peoples.
Much more is needed to be done as we cannot afford to lose a square metre more. The recent IPCC report has once again reminded us how important it is to act immediately to reduce emissions, including by protecting forests, while there is a chance. Ancient cultures that built Machu Picchu and the Gran Pajatén cities thrived in those environments without altering it. Why not us? Cloud forest protection needs more attention, scientific research, funding, and technical support. But everyone is starting to realize what their status is and that they truly matter.
There may not be green dwarfs jumping from behind rocks, but there are perfectly translucent Glass Frogs calling for the clouds, bright orange Cock of the Rocks dancing in groups and competing for the attention of a female, miniature orchids as little as a headpin, moths as big as your hand, and armadillos that are as hairy as a Rolling Stone. To me, besides the climate reasons, that is the magic we need to preserve.
Enrique G. Ortiz
Peruvian Tropical Ecologist
