Expected global suitability of coffee, cashew and avocado due to climate change

rated as S3 or higher, the overall suitability would therefore be S3. The resulting global maps show the potential land suitability of the studied crop under rainfed conditions, without taking into account agricultural management options such as liming or irrigation. The results are based on growth factors that are sufficiently described for the respective crop and where corre- sponding global spatial datasets are available. Suitability evaluations were undertaken for cur- rent and predicted future climatic conditions. Current suitability modelling For the modelling of the current global land suitability for the three plantation crops, their bio- physical requirements were identified via a literature search. Table 1 lists their climatic, land and soil requirements that were used in the model, classified into the four suitability classes. This classification was done based on Sys et al. [24] taking into account additional scientific lit- erature (see Table 1). Whenever several authors defined different thresholds between suitabil- ity classes of a criterion, the threshold was set conservatively resulting in a higher crop suitability or it was set in agreement with the majority of indications. Global climate and land/ soil raster data with a spatial resolution of 30 arc seconds were used from established global cli- mate models and satellite-data based global land use datasets and are listed in Table 2. Artificial surfaces according to the FAO Global Land Cover SHARE dataset [31] and protected areas

based on the World Database on Protected Areas [32] were rated as ‘unsuitable’ (see Table 1). The length of the dry season was based on the monthly precipitation (P) and the potential evapotranspiration (PET), and was calculated as the number of months where P < ½ PET [24]. Coffee, cashew and avocado have similar ecological niches (Table 1). However, there are still important differences in their biophysical requirements. While avocado has the highest suitable temperature range, coffee is most susceptible to high temperatures. At the same time, avocado is more susceptible to low temperatures than the other crops during the coldest month. With regard to precipitation, cashew has the highest suitable range, tolerating both higher and lower values than coffee and avocado. Avocado is most susceptible to high precipi- tation, but more tolerant to longer dry seasons. Both avocado and coffee have a slightly reduced suitability in regions without a dry season. When looking at edaphic factors, coffee has a narrower ecological niche than the other crops. Compared to coffee, both cashew and avocado are more tolerant to high and low soil pH and less restricted regarding soil texture. Combining all these factors, cashew has the broadest ecological niche, followed by avocado and coffee. For each criterion listed in Table 1, the crop suitability was calculated globally. The results for all five climate requirements and for the eight land and soil requirements were then aggre- gated by the lowest suitability value to obtain the overall climate suitability and land and soil

suitability, respectively [22]. Finally, the climate and the land and soil suitability were com- bined once again by the lower rate, resulting in the overall current suitability. For the identifi- cation and discussion of most limiting factors in the different regions, the individual suitability maps for the different requirements were compared. All analyses were done using the ESRI ArcGIS Pro software version 2.5.0. Future suitability modelling To estimate the potential effects of climate change on future suitability, the impacts were mod- elled based on three representative concentration pathways (RCPs; [39]) for the future climatic conditions of 2050 (average of projected climate from 2041–2060). Downscaled CMIP5 data [40] of 14 global climate models (GCMs: BBC-CSM1-1, CCSM4, CNRM-CM5, GFDL-CM3, PLOS ONE Global suitability of coffee, cashew and avocado PLOS ONE | https://doi.org/10.1371/journal.pone.0261976 January 26, 2022 5 / 24