# Review of Remote Sensing Methods to Map Coffee Production Systems
## 1 Introduction
### Review of Coffee Characteristics and Systems
Furthermore, the biodiversity supported by coffee production and surrounding habitats is generally lower in unshaded systems, and monoculture production has also been associated with a weaker response to pest outbreaks and increased pathogen transmission ([PERSON] et al., 2020; [PERSON] et al., 2021; [PERSON] et al., 2021). In addition, the lack of mature and diverse vegetation and increased amount of exposed soil, a characteristic of monoculture systems, can lead to erosion, further decreasing the resilience and nutrient uptake in these systems ([PERSON] et al., 2021). Coinciding with the transition to unshaded monoculture coffee systems has been a diversification of canopy structures and management styles within shaded coffee systems. These different agroforestry systems have significant variations in terms of the provision of ecosystem services and environmental impacts ([PERSON] et al., 2019). Researchers often describe four different typical shaded coffee systems, varying in vertical and compositional diversity of shade ([PERSON] et al., 2019; [PERSON] et al., 2021). These systems include understory rustic polyculture, traditional polyculture, commercial polyculture, and shaded monoculture (see Figure 1 from Moguel and Toledo (2019)). Rustic polyculture systems are characterized by an intact forest canopy and minimal understory alteration--only enough to grow coffee plants successfully. In traditional polyculture \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Rank** & **Country** & \begin{tabular}{c} **Coffee** \\ **Production** \\ **2017 (tons)** \\ \end{tabular} & \begin{tabular}{c} **Area** \\ **Harvested 2017** \\ **(ha)** \\ \end{tabular} & \
\begin{tabular}{c} **Export Value** \\ **of Coffee** \\ **Products, 2017** \\ \end{tabular} &
\begin{tabular}{c} **Percent of Crop and** \\ **Livestock Product** \\ **Exports by Value, 2017** \\ \end{tabular} \\ \hline
1 & Brazil & 2,684,508 & 1,802,417 & \$5.27 billion & 6.62\% \\
2 & Vietnam & 1,542,398 & 605,178 & \$3.50 billion & 15.9\% \\
3 & Colombia & 760,209 & 799,046 & \$2.81 billion & 39.5\% \\
4 & Indonesia & 668,677 & 1,253,796 & \$1.66 billion & 4.22\% \\
5 & Honduras & 473,718 & 434,312 & \$1.29 billion & 48.8\% \\
6 & Ethiopia & 467,679 & 694,179 & \$955 million & 44.0\% \\
7 & Peru & 337,330 & 424,129 & \$710 million & 13.5\% \\
8 & India & 312,000 & 449,357 & \$968 million & 2.86\% \\
9 & Guatem & 246,319 & 281,841 & \$749 million & 14.1\% \\
10 & Uganda & 209,421 & 379,108 & \$555 million & 34.8\% \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Statistics on the top ten coffee-producing countries ranked by coffee production. Data collected from the Food and Agriculture Organization of the United Nations (2019). systems, farmers maintain the integrity of the canopy but replace the entire understory with coffee and other shade-tolerant plants. In commercial polyculture systems, farmers remove both the canopy and understory, replacing the understory with coffee and the canopy with smaller trees that provide minimal shade but offer a commercial value. Finally, shaded monoculture, considered a modern shaded system, is created by removing both the canopy and understory and planting a leguminous canopy almost exclusively to provide shade for the coffee below [34; 35]. While these systems categorize general, shaded management practices based on canopy and understory density, they do not represent an exhaustive list of the possible production systems throughout the world. For example, [PERSON] et al. [36] discuss the diversity of systems in Brazil, reporting that they exist with and without irrigation, with and without windbreaks, and with crops of different ages, areas, spacing, and varieties. For this study, we specifically focused on the distinctions captured by Moguel and Toledo [34] to highlight the diversity in vegetation structure. While each system has both advantages and disadvantages in terms of productivity, management intensity, and environmental impacts, the suitability of a given system varies based on landscape characteristics.