July 9th, 2019

Agroforestry Solutions for Colombia’s Floods and Landslides

In just two weeks, from April 1, when Colombia’s rainy season began, to April 13, the country’s National Unit for the Management of Disaster Risk (UNGRD) recorded 57 severe weather events. Torrential rainstorms led to dozens of landslides and floods around the country. Many of these resulted in the loss of life and homes. As of early June, at least eight river locations in the northwest portion of the country were at red alert levels, affecting tens of thousands of Colombians across the country. According to the FAO, the number one cause of landslides of this magnitude is excessive soil water content. Steep slopes and weak soils contribute to landslide risk, and when heavy rains come—like Colombia has experienced much of this spring and early summer—whole hillsides give way, wreaking havoc on the land and its inhabitants. Though the consequences of landslides are dire, agroforestry solutions to contributing factors are not only accessible; they can also be profitable for those who employ them

Agroforestry Solutions for Colombia’s Floods and Landslides

One of the fundamental principles of agroecology is learning to work with natural rhythms, not against them. Rising rivers are not always a problem. In fact, for much of human history, growers have celebrated spring flooding, as the floods lay down rich sediment full of moisture and nutrients on riparian fields. A problem occurs when the rushing waters cause more damage in the process than they offer solutions. With this is mind, agroecologist Gary Nabhan has worked with farmers around the world to learn and test a simple, traditional agroforestry solution.

For farmers planting fields on the edge of rivers and creeks, the first step towards safely harnessing the river’s gifts is planting trees along the bank. The roots of those trees stabilize the soil and act as the posts of a woven fence known as cercos de tejido. Limbs are trimmed from the lower half of the trees and brush and tree limbs are woven between the trunks. This creates a sieve on the river’s edge. When floods come they must pass through the living fence on the bank, leaving heavy detritus on the edge of the field and coating the cropland in rich fertilizer.

One farmer Nabhan worked with, Don Beto, claimed that riparian fields managed by his family enjoyed enhanced fertility for up to five years following a significant flood. Nabhan’s studies “confirmed that his soil had levels of organic matter and moisture-holding capacity comparable to the best midwestern and southern farms along the Mississippi River.”

Tree planting provides a host of benefits for any landscapes at risk of landslides, not just along riverbanks. Their deep root systems draw out excess water from the soil and hold the soil in place, especially along steep slopes. In the case of small slides or rockfalls, trunks can also obstruct the slide, preventing further damage.

Of course, many of the slides in Colombia are so dramatic that even tree cover does not impede them. That is why the preventative measures agroecology provides are so important. Unfortunately, Forest News reports, many smallholders, especially those who don’t hold long tenure on their property, understandably struggle to initiate such a forward-facing solution when the immediate future requires their full attention.

This makes it even more important that long-tenured farmers and projects incorporate perennial trees into agricultural ecosystems, through agroforestry, silvopasture, or riverbank plantings. Farmers utilizing agroforestry solutions, such as those at Ganaderia Pietrasanta, can provide security for their fields and their neighbors. They also diversify their revenue stream by incorporating an additional crop. Tree by tree, we can work to ensure rain and rising rivers are once again received as gifts, not disasters.

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