Ecology: Over 64% of suitable elephant habitat lost across Asia since 1700
Habitats suitable for Asian elephants (Elephas maximus) across Asia have decreased by over 64% – equating to 3.3 million square kilometres of land – since the year 1700, estimates a study published in Scientific Reports. The authors suggest that habitat loss from 1700, after centuries of relative stability, coincides with the colonial-era use of land and subsequent agricultural intensification in South Asia.
Asian elephants live in a range of habitats including grasslands and rainforests, but with increasing human use of land and habitat loss, elephants can come into conflict with humans. To assess the historical distribution of elephant habitats and land-use change, data on elephants and environmental factors can be modelled to infer habitat suitability across an area and over time.
Shermin de Silva and colleagues estimated the change in the spread and fragmentation of Asian elephant ecosystems in 13 countries between the years 850 and 2015 and calculated the change in suitable habitat from 1700 to 2015. Habitats were categorised as suitable if they exceeded a threshold defined and modelled according to ecological criteria including the percent of primary forests and pastures, non-forested vegetation, cropping and irrigation patterns, wood harvest rates and urbanization, amongst other factors.
The authors compared an area within 100km of the current range of elephants in Asia and found that in 1700, 100% of the area could have been considered suitable habitat but by 2015 less than half was considered suitable (48.6%). They suggest that mainland China, India, Bangladesh, Thailand, Vietnam, and Sumatra have each lost more than half of their suitable elephant habitat range, with the greatest declines in China (around 94% of suitable habitat lost) and India (around 86% of suitable habitat lost). Estimates of land in Borneo suggest it has gained habitat that is suitable for elephants. The authors suggest that the decrease in suitable habitat for Asian elephants may drive potential conflict between elephants and people.
The authors conclude that it is important to consider the history of the landscape to understand the distribution of elephants in Asia and to help develop more sustainable land-use and conservation strategies to meet the needs of both elephants and people.
source-Scientific Reports
