# Review of Remote Sensing Methods to Map Coffee Production Systems
## 1 Introduction
### Review of Coffee Characteristics and Systems  
Coffee originated as a wild crop in Ethiopia and has since expanded to become a globally traded and consumed commodity. Today, coffee is grown in approximately 70 countries throughout the tropics, in a region referred to as \"The Bean Belt\" [11; 12]. Most coffee is produced on relatively small farms in areas with rugged terrain [13]. In fact, 70% of coffee is produced by smallholder farmers who depend on coffee production for their livelihoods and are extremely vulnerable to variations in production due to climate change [14; 15]. Despite the competing land-use pressures and threats to production from climate change, the coffee industry continues to grow and represents a very important economic opportunity for many countries (Table 1). Two major commercial varieties, Coffea arabica and C. robusta, dominate the coffee market. Other, less viable varieties, such as C. liberica, represent a small portion of the market. While arabica beans comprise approximately 70% of the global market and are generally considered a higher quality coffee bean, arabica coffee trees are smaller and less productive compared to robusta coffee trees [17], they must be grown at high altitudes, and require mild temperatures and high rainfall. Conversely, robusta coffee trees, the beans of which account for about 30% of the global market, are more tolerant of a broader range of climates and elevations and have proven more resistant to diseases and parasites [12; 17; 18]. Arabica and robusta are both grown in a range of production systems throughout the globe. These production systems range from growing the crop under canopies in shaded agroforestry systems containing different levels of shade and canopy structures to large monoculture sun systems that are similar to other intensive row cropping production systems. Historically, farmers cultivated coffee in shaded systems to mimic the natural forest growing conditions of coffee plants. The complexity of the canopy and associated vegetation in shaded systems typically contain high levels of biodiversity (for example, [PERSON] et al. (2019) found that some shade systems had greater than or equal ant and bird richness as nearby forests) and serve as valuable areas for the provision of ecosystem services, such as carbon sequestration and climate change mitigation ([PERSON] et al., 2019; [PERSON] et al., 2019; [PERSON] et al., 2020; [PERSON] et al., 2021; [PERSON] et al., 2020; [PERSON] et al., 2021; [PERSON] et al., 2021; [PERSON] et al., 2022). This is particularly true where such agroforestry systems are supported by adjacent forest ecosystems ([PERSON] et al., 2020). In recent decades, farmers have increasingly converted shaded systems to large-scale, unshaded monoculture systems ([PERSON] et al., 2020). While this shift in production systems can be traced to large-scale agronomic policies and market restructuring, the impact of these forces on coffee growing practices differs across regional landscapes, with trends of widespread shade tree removal more prevalent in some countries (e.g., Colombia, Costa Rica) and little to no shade tree removal in others (e.g., Guatem, Nicaragua) ([PERSON] et al., 2019). According to [PERSON] et al. (2019), as of 2010, over 40% of coffee was produced in unshaded systems. Farmers have pursued unshaded monoculture systems for two main reasons. First, removing the shaded canopies reduces moisture that can sometimes, in excessively wet conditions, lead to a devastating fungal disease called coffee leaf rust. Second, monoculture production allows for increased coffee plant density and therefore increased total crop yield, thus enabling cost-effective farming practices ([PERSON] et al., 2019; [PERSON] et al., 2021). However, unshaded monocultural production can substantially reduce biodiversity and the carbon sequestration potential evident in shaded systems ([PERSON] et al., 2019; [PERSON] et al., 2021; [PERSON] et al., 2021; [PERSON] et al., 2021).