Elephant Habitats Across Asia Have Declined By More Than 64% Since 1700: Study
Habitats of Asian elephants range from grasslands to rainforests. The total area of elephant habitats lost across Asia is equal to about 3.3 million square kilometres of land
Since the year 1700, habitats for Asian elephants (Elephas maximus) across Asia have declined by more than 64 per cent, coinciding with colonial-era use of land and agricultural intensification in South Asia, according to a new study. The total area of the habitats lost is equal to about 3.3 million square kilometres of land, a study published in the journal Scientific Reports says. Habitat loss started from 1700, after centuries of relative stability.
The colonial-era practices which are believed to have led to habitat loss for Asian elephants include timber extraction, and farming and agriculture. These activities cut the average habitat patch size more than 80 per cent, from 99,000 to 16,000 square kilometres.
How the study was conducted
Habitats of Asian elephants range from grasslands to rainforests. However, elephants often come into conflict with humans due to increasing human use of land and habitat loss. The authors modelled data on elephants and environmental factors to infer the suitability of different elephant habitats over an area and over time, and to assess the historical distribution of elephant habitats and changes in land-use.
Shermin de Silva from the University of California, San Diego, and her colleagues estimated the change in the spread and fragmentation of Asian elephant ecosystems in 13 countries between the years 850 and 2015. Using these estimates, they calculated the change in suitable habitat from 1700 to 2015.
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What habitats are considered suitable for elephants?
The habitats which exceeded a threshold defined and modelled according to ecological criteria, including the percentage of primary forests and pastures, wood harvest rates, non-forested vegetation, urbanisation, and cropping and irrigation patterns, among other factors, were categorised as suitable.
After comparing an area within 100 kilometres of the current range of elephants in Asia, the authors found that in 1700, 100 per cent of the area would have been considered suitable. However, by 2015, less than half of the area was considered suitable. Only 48.6 per cent of the area remained suitable for elephants.
Which areas have had significant habitat loss for Asian elephants?
According to the study, mainland China, India, Thailand, Sumatra, Bangladesh, and Vietnam have each lost more than half of their suitable elephant range. The greatest declines in elephant habitats have occurred in China and India. In China, there was around 94 per cent of suitable habitat loss, and in India, there was around 86 per cent of suitable habitat loss.
Borneo, the third-largest island in the world and the largest in Asia, has gained habitat that is suitable for elephants, the study suggests. Due to the decrease in suitable habitat for Asian elephants, there is a possibility of conflict between humans and elephants in the future.
What are the major reasons behind habitat loss for elephants?
The major reasons which led to accelerated decline of elephant habitats over the past century are human interventions and climate change. However, it is difficult to study the result of these changes on wildlife over the long term due to the lack of historical data.
In the past three centuries, there has been a loss of traditional systems of management. This is another significant reason behind the loss of habitats of Asian elephants.
In order to understand the distribution of elephants in Asia and to develop more sustainable land-use and conservation strategies to meet the needs of both elephants and people, it is essential to consider the history of the landscape, the authors conclude.
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