March 7, 2019
By Elizabeth Norikane, East Africa Communications Specialist with contributions from Andrew Zacharias, Deputy Director of Monitoring and Evaluation
When standing in a Forest Garden, you can feel the life around you. Year to year, it feels greener, lusher, and more alive. However, measuring this can be difficult. While we find counting trees and discussing soil health with farmers to be good markers of progress, we continue to explore better ways to measure our environmental impact.
For years, TREES has leveraged emergent technologies to improve their monitoring and evaluation of projects. In 2014, we launched a mobile data collection system to allow TREES technicians to collect data in last-mile environments. This has enabled them to complete thousands of surveys every year and keep the organization informed of the progress and impact of their participants. As technology develops, TREES carefully considers its application to our work and we are always looking for new opportunities to learn and share more information about our impact.
One of these exciting new ways TREES aims to measure impact is with the use of drones, also known as Unmanned Aerial Vehicles (UAVs). In the agricultural industry, drones have revolutionized the way farmers monitor their crop systems. Drones fly under cloud cover, close to the ground, using photogrammetry- or measurements from photographs- to measure various indicators. Drones have been used in the agriculture industry to monitor crop health, yield estimates, weather patterns, and environmental impact.
At TREES we specifically aim to measure the impacts of the Forest Garden Approach (FGA) on people, profit, and planet. Currently, we have robust measures to track and measure food security, dietary diversity, economic resilience, and agriculture production. And most recently, TREES has been using drones to monitor the physical changes of our farmers’ fields. In doing so, we have chosen to measure Leaf Area Index (LAI) which tracks the Forest Garden’s ability to store water and maintain microclimates, which are climates of very small or restricted areas, distinct from the climate in the surrounding vicinity.
We consider the establishment of a microclimate to be an environmental success of the FGA. In these microclimates, water is retained more effectively, thereby producing more food for longer periods of time. The increase in vegetation that results from the Forest Garden has a close relationship with air temperature, humidity, and soil health. In addition to green cover throughout a Forest Garden, it is the higher tree canopy cover that effectively blocks the wind and sun from reaching the soil beneath. Additionally, the canopy holds water vapor and retains humidity thereby keeping the soil moist and preventing soil erosion. In short, a higher LAI means better growing conditions.
Unfortunately, calculating LAI usually requires invasive cutting of vegetation. Because we do not want to do that on our farmers’ plots, we have created a measure to best assess this using the imaging from the drone alone. The images are run through applications that are able to use the photos to differentiate between synthetic material, soil, and plant life.
We first introduced our drone monitoring in 2018 at our project sites in Singida, Tanzania, located in East Africa. Singida is tropical savannah and faces issues of low rainfall – it is hot and dry much of the year, which can prove to be difficult growing conditions. The data our staff gathered from the drone flyover showed that a vast majority of our new farmers had scarce or non-existent leaf covering, showing that the farmers face a big challenge ahead. This aligned with what could be seen walking among the plots – very few, if any, trees and barren of vegetation. If anything was seen, it was often weeds or cornhusks leftover from harvest. When crops were planted, it was usually one cash crop, planted in an unsustainable fashion. This means during the dry season, the sun scorches the fields and high winds blow away the topsoil. During the rainy season, the topsoil is swept away by fast-moving rainwater. Thankfully, we know that as the Forest Garden increases its biomass and LAI score, microclimates will be created where the soil is protected, moisture is retained, and temperatures cool, so plants are able to thrive.
We are thrilled to add to our robust collection of data in proving the effectiveness of the Forest Garden Approach. TREES has years of data relating to food security, dietary diversity, economic resilience, and productivity that prove two of our three pillars: people and profit. Now, with the assistance of drone technology, we are beginning to show how to impact our final pillar: planet. We look forward to expanding this monitoring beyond Tanzania and into our other project sites to watch the way in which our farmers land transforms through the implementation of our program – enhancing their lives and improving the planet at the same time.