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

Abstract

0.AbstractCoffee is produced under different management systems and scales of production, which can be categorized as Syndromes of Production. The “Capitalist Syndrome” is characterized by a high use of inputs such as capital and labor to increase agricultural outputs. This syndrome results in practices like high planting density, that may promote the development and dispersal of important diseases like the coffee leaf rust (CLR). The arrangement of plants can drive the spatial movement of the harvesters, who can bear and disperse CLR across and within plantations. Furthermore, in most capitalist coffee plantations, harvesters work multiple hours to maximize the daily harvest, which might increase CLR dispersal. 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 CLR dispersal. We present a description and qualitative analysis of the daily spatial movement of harvesters in two large-scale capitalist coffee plantations: an organic and a conventional plantation. Using 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. Our model differentiated two kinds of movements: 1) when trees have berries, harvesters remain in the same rows or areas nearby (Collect state; 94-98% of the steps); 2) when not, harvesters make longer steps within the harvesting zone 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. To reduce the possible impact of human dispersal of pathogens, we suggest shorter 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 an organic coffee management that could prevent diseases, increase diversity, and guarantee just and safe conditions for workers.

Interplay between harvesting, planting density and ripening time affects coffee leaf rust dispersal and infection

“…The objective of implementing a computational modeling approach was twofold: i) test if the temporal differences in ripening between the trees are sufficient to reproduce the reported trajectories of the workers during harvest (as previously speculated by Mora Van Cauwelaert et al, 2023b), and ii) explore the effect of these trajectories for dispersal and average rust infection in coffee plots. We first simulated coffee plots with different planting densities, interplant ripening scenarios and a closest-neighbor harvesting rule to study the role of ripening on harvesting trajectories.…”

“…According to previous studies one worker collects around 30 plants per hour, or roughly 250 plants in eight hours (i.e. one harvesting day; Mora Van Cauwelaert et al, 2023b). In the following simulations, we adjust the number of workers in the plots to always represent one harvesting day with 250 harvesting steps per worker (e.g.…”

“…Besides, the dynamics of harvesting in coffee plantations depend on the scale, on specific ecological and management characteristics, but also on land tenure regimes and goals of production; or on what has been called “the syndrome of production” (Andow and Hidaka, 1989; Perfecto et al, 2019). In large-scale and landlord-owned plantations, the trajectory of paid workers during harvest relies, among other factors, on the ripening synchronization of the berries between the trees in the plot (Mora Van Cauwelaert et al, 2023b). Distinct trajectories, with short or long steps between plants, could play a differential role in CLR dispersal and its impact on plantations (Mora Van Cauwelaert et al, 2023b).…”

“…In large-scale and landlord-owned plantations, the trajectory of paid workers during harvest relies, among other factors, on the ripening synchronization of the berries between the trees in the plot (Mora Van Cauwelaert et al, 2023b). Distinct trajectories, with short or long steps between plants, could play a differential role in CLR dispersal and its impact on plantations (Mora Van Cauwelaert et al, 2023b).…”

“…Here we present a mathematical model to study the workers’ spatial movement during coffee harvesting and its contribution to CLR dispersal and infection at a plot level. We first explore how the spatial trajectories drawn by the workers in large-scale plantations (Mora Van Cauwelaert et al, 2023b) could be reproduced in simulated coffee plots with different berries maturation synchronicity. We then evaluate how these trajectories modify rust dispersal and affect the final CLR infection in plots with increasing planting densities.…”