Spatial trajectories of coffee harvesting in large-scale plantations: ecological and management drivers and implications

Abstract

CONTEXTCoffee is produced under different management systems and scales of production categorized as Syndromes of Production. The "Capitalist Syndrome" is characterized by the high use of capital and labor inputs to increase agricultural outputs. This syndrome results in practices like high planting densities that may promote the development and dispersal of plant pathogens like coffee leaf rust. The spatial arrangement of coffee trees drives the spatial movement of the harvesters, who can bear and disperse pathogens across and within plantations. In most capitalist coffee plantations, harvesters work multiple hours to maximize the daily harvest, which might increase their dispersal potential. However, their spatial movement has not yet been described, nor its relationship with the scale or management of the plantation, and even less its ecological implications for pathogens dispersal. OBJECTIVEWe describe and analyze the daily spatial movement of coffee harvesters in two large-scale capitalist plantations: an organic and a conventional plantation. METHODSUsing state-space models, we recorded and analyzed the spatial movements of harvesters. We then constructed a driver tree for harvest dynamics, which incorporated qualitative variables related to climate, coffee plants, and management aspects reported by the harvesters. RESULTS AND CONCLUSIONSOur model differentiated two kinds of movements: 1) when trees have berries, harvesters remain in the coffee rows or areas nearby (Collect state; 94-98% of the steps); 2) when not, harvesters make longer steps within the harvesting location or move to another area (Search state; 2-6% of the steps). In the organic plantation, the Search state had a longer-tailed step-length distribution than in the conventional plantation, resulting in a significantly higher visited area per worker (p<0.05). This might be related to a) a lower fruit load or percentage of trees with ripe fruits when we took the data or b) smaller harvesting locations ("pantes") per number of harvesters. Harvesting movements that explore a wider area, either by visiting more plants or by changing locations on the same day, could create more foci of CLR infection across the plantation. SIGNIFICANCEOur results highlight practices that can reduce the possible impact of human dispersal of pathogens like shorter harvesting trajectories by working fewer hours a day or avoiding harvesting at the end of the maturation season when few trees have berries and harvesters have to travel longer distances. This calls for organic coffee management that could prevent diseases, increase diversity, and guarantee just and safe conditions for workers.