Improving spatial transferability of ecological niche model of Hevea brasiliensis using pooled occurrences of introduced ranges in two biogeographic regions of India

Abstract

Improved spatial transferability of ecological niche models is crucial for accurately predicting species preferred habitat; this is especially true for a planted tree species (Hevea brasiliensis Muell. Arg.). Amazonian valley of South America (AZ) is known as native range of this species. To test the transferability of Maxent ecological niche model among two distinct bio-geographical regions of India, Western Ghats (WG) and North-East (NE) regions and AZ, the present study was designed. The present spatial distribution of H. brasiliensis was evaluated using the Maxent algorithm using bioclimatic variables and species occurrence data from respective regions. An alternate approach of calibrating the model with pooled occurrence points of various introduced ranges of the species was adapted for predicting the species' presence in unsampled region.Spatial distribution of Hevea species in two biogeographic regions of India modelled by Maxent was found to be quite accurate when the model was calibrated with the sampled occurrence points of the same region as evidenced from our previous studies. However, the present study addresses the issue related to transferability of niche based model to predict the probable distribution of Hevea species in an unsampled region based on either its native or introduced range of the species. The result indicates that transferability depends on the extent of similarity between the climatic spaces occupied by the species in sampled region and unsampled regions of the species' distribution. The spatial transferability of the model was improved by using pooled occurrence data of the species from both introduced regions.