Impact of swidden agriculture on palm populations in South-Central Guyana

Indigenous peoples across the tropics harvest fauna and flora from the local environments that they helped to shape. Among the flora that are harvested are palms that are distributed across swidden agriculture landscapes. Here we draw on imagery derived from unmanned aerial vehicles (UAVs) and convolutional neural network (CNN) object detection techniques to identify individual palms within a localized region of swidden agriculture in Guyana. A total of 10,194 palms were identified from six different species over 255 hectares. Land disturbed by swidden agriculture saw a 136% increase in palm density compared to undisturbed forest (53.3 versus 22.6). Local Moran’s I cluster analysis showed that Attalea maripa was the dominant species in both undisturbed forest, representing 77.1% of palms, and swidden-disturbed land, representing 89.0% of palms. Astrocaryum vulgare declined in relative representation from 17.3% in undisturbed forest to 10.0% in disturbed forest, accompanied by reduced representation of other less abundant palms. These results demonstrate that swidden disturbance can increase total palm density while simplifying the palm assemblage and reducing the relative representation of less abundant species. This trade-off is important for informing more sustainable land-use pathways that maintain the livelihood and cultural functions of swidden agriculture while conserving palm-community diversity. Furthermore, 0.5-meter-resolution multispectral WorldView-2 imagery detected approximately 70% fewer palms than UAV imagery.Author summary: Indigenous communities throughout tropical regions often rely on traditional shifting cultivation, known as swidden farming, to grow staple crops and sustain livelihoods. They also commonly depend on local palm species for food, medicine, and building materials. While farming and palm use have been studied separately, the relationship between agricultural practices and palm species diversity remains less understood. Using drone imagery collected over forests and farming areas in Guyana, we found that shifting cultivation was associated with substantially greater overall palm abundance than tall-canopy forest. However, this increase was concentrated mainly in one dominant species, Attalea maripa, while other palms became less represented. Greater palm abundance therefore did not correspond to a more diverse palm community. Drone imagery also provided substantially more complete palm counts than satellite imagery. Recognizing the trade-off between overall abundance and community diversity can support land-use approaches that sustain Indigenous food production and culturally important resources while maintaining ecological diversity across swidden landscapes.