Predicting the distribution of parthenium weed (Parthenium hysterophorus) under current and future climatic conditions in Bhutan

Abstract

Invasion, spread and establishment of invasive alien species in a new environment causes serious ecosystem perturbation and native species extinctions. The problem is further aggravated under climate change as some invasive alien species perform better under elevated temperature and carbon dioxide regimes. Currently unsuitable regions such as high-altitude areas and mountains are likely to become more suited to invasion under future climatic conditions. We have modelled the distribution of one of the most invasive alien species, parthenium weed ( Parthenium hysterophorus L.) which is rapidly colonizing different parts of Bhutan. We have implemented ensemble modelling approach using the BIOMOD2 package in R environment. Under current climate scenario, about 2.83% (1, 099.01 km 2 ) of the country’s total area is predicted to be suitable for parthenium weed invasion, covering 17 out of the 20 districts in Bhutan. Under future climate scenarios, the highest suitability is predicted under RCP4.5 2050 period with about 5, 419.69 km 2 anticipated to be suitable. Except for Bumthang, all districts show suitability to invasions under future climate scenarios. Generally, districts located in the west and south show more suitability than those in the east and central region. The highest elevation of suitability is predicted to be at 2, 931 m above sea level; an upward shift of about 753 m. Based on these findings, there is an urgent need to develop management programs and raise public awareness on the adverse impacts of parthenium weed in Bhutan.