An Integrated Approach to Map the Impact of Climate Change on the Distributions of Crataegus azarolus and Crataegus monogyna in Kurdistan Region, Iraq

Abstract

The hawthorns Crataegus azarolus L. and Crataegus monogyna Jacq are two ecologically and medicinally important endemic tree species that occur only in forests of oak in the mountain ranges of the Kurdistan region of Iraq (KRI). These species have been degrading across the mountain ranges at an alarming pace due to climate-related factors (e.g., wildfire events and drought) and anthropogenic drivers. Nevertheless, there is a gap in understanding their distributions today and in the future under a changing climate in Iraq. To address the species’ knowledge gap and thus establish a baseline for a future management and conservation strategy, this study used field observation records, species distribution modeling integrated with GIS techniques, and relevant environmental predictors to (i) estimate the species’ potential distributions and map their current known distributions across unsurveyed areas; (ii) model the species’ possible response under several scenarios for a weather change in the future; (iii) map the species’ overlap ranges and the direction of the distributions. Results suggest that under two global climatic models (GCMs), BCC-CSM2-MR and CNRM-CM6-1, the overall habitat expansion magnitude for the two species would be less than the overall habitat reduction magnitude. For C. azarolus, the habitat range would contract by 3714.64 km2 (7.20%) and 3550.47 km2 (6.89%), whereas it would expand by 2415.90 km2 (4.68%) and 1627.76 km2 (3.16%) for the GCMs, respectively. Modeling also demonstrated a similar pattern for C. monogyna. The species overlap by 7626.53 km2 (14.80%) and 7351.45 km2 (14.27%) for the two GCMs. The two species’ habitat ranges would contract significantly due to the changing climate. The direction of the species’ potential distribution would be mostly toward the KRI’s east and southeast mountain forests. Our results, for the first time, provide new data on the species’ present and future distributions and outline the advantages of distribution modeling combined with geospatial techniques in areas where species data are limited, such as Iraq.