Prediction of global distribution of Ganoderma lucidum (Leys.) karsten: A machine learning maxent analysis for a commercially important plant fungus

The global habitat suitability of the fungus Ganoderma lucidum was simulated using the Maxent machine learning technique in relation to a number of environmental factors. 1159 geographically thinned G. lucidum presence points were projected over three bio-climatic time frames: current, 2050 and 2070, using four representative concertation paths (RCPs), namely 2.6, 4.5, 6.0 and 8.5 along with few nonclimatic variables like e ecosystem rooting depth and r ooting zone water storage size and s surface soil characteristics. With these climatic and RCPs projections, areas under the receiver operating curve (AUC) were reached 0.90, suggested the excellent predictive qualities of the modelling. Based on Maxent output, habitat suitability types were identified using theARC-GIS raster calculator tool, which provided optimum, moderate, marginal, and low suitability classes. The largest optimum habitat for this fungus was detected during current bioclimate time-frame, measuring 2983977.56 square kilometres, while smallest area (600355.52 square kilometres) under this niche type was recoded under 2050 RCP 6.0. By doing so, percent changes in each habitat class from their respective current to future projections were estimated and our analysis revealed -41.82 to -79.88 percent reduction for the optimum habitat areas. The Permutation Importance value indicated that energy/temperature variables have a much greater influence on this species' global niche distributions than do water variables, and these variables were identified as important predisposing factors for this fungus. Secondary predisposing variables for this fungus included an eightcentimetre ecosystem rooting depth and soil organic carbon levels of up to 145 (g/kg). From present study, it can deduce that this fungus is always present in specific European countries. However, both optimum and moderate habitat suitability for this species will deteriorate within Asian countries, making wild collection for various medicinal product synthesis more difficult. As a result, its availability in such areas will be heavily reliant on its in-vitro conditions (substratum) as well as the adjustment of micro-environmental variables identified in this work.