Integrated Approach to Accounting for Environmental Factors in Models of the Current Distribution and Climatic Dynamics of Ambrosia artemisiifolia L. in the Caucasus

Abstract

Current climate change, habitat degradation, and road network development contribute to the invasion of alien plant species in areas of more northern latitudes and higher altitudes. Using the maximum entropy method (Maxent), we built spatial distribution models of Ambrosia artemisiifolia, considering abiotic, biotic, and anthropogenic factors and accessibility to the area. Maps of the species current distribution in the Caucasus and its range dynamics according to the climate change scenarios were constructed. The most important variables determining A. artemisiifolia spatial localization in the region were as follows: distance to roads (not more than 0–5 m), terrain roughness (gentle areas), and humidity (climate from semiarid to perhumid). The distance of 0–5 m is also characterized by the area accessibility factor (species dispersal capacity), which contributed about 47% to the final model. Species dispersal beyond roadsides was hindered by forests and meadows with the probability of A. artemisiifolia occurrence not exceeding 0.01%. The species core ranges were predicted in foothills and low mountains of the Western and Central Caucasus, Western and Central Transcaucasia, the northwestern Lesser Caucasus, and the Caspian Sea coast. The species invasion in highlands could occur along the gentle river valleys that concentrate the main mountain roads. According to the pessimistic and optimistic climate change scenarios, by 2100, the decline in optimal A. artemisiifolia habitats will be 87 and 27%, respectively, and will affect mainly the plain areas of the currently most humid regions. The main core ranges were predicted in the middle mountains and highlands of the Caucasus.