Over 64% of suitable elephant habitat has been lost

2023-04-28 14:39:18

Habitats suitable for Asian elephants (The largest elephant) across Asia have declined by more than 64%, equivalent to 3.3 million square kilometers of land, since the year 1700, estimates a study published in the journal Scientific Reports ⁽¹⁾.

The authors suggest that habitat loss after 1700, after centuries of relative stability, coincides with colonial land use and subsequent agricultural intensification in South Asia.

Asian elephants live in diverse habitats such as grasslands and tropical rainforests, but with increasing human use of land and loss of habitats, elephants can come into conflict with humans.

Land use change is associated with the loss of elephant ecosystems in Asia for several centuries

Places of appearance of elephants ( a ) Brown shaded region shows presumed historic postglacial range, smaller purple polygons show current range, dots show sampled occurrences. Map created by S. de Silva in Quantum GIS ( b ) Examples of Asian elephant ecosystems. Upper panel: Anthropogenic water sources of different ages and scales at which elephants congregate in Sri Lanka. ( i ) A small reservoir originally built and maintained at the village level with resettled inhabitants in the 1980s after the creation of Udawalawe National Park, now maintained by wildlife managers. ( yo) A large dammed reservoir completed in the 1970s and maintained by the national government, the impetus for the creation of the Udawalawe National Park. ( iii ) The great Minneriya Reservoir built by King Mahasen in the 3rd century and restored in the 19th century after the British occupation. Small reservoirs provide year-round water, while large reservoirs also produce floodplain vegetation for forage. Bottom panel: Asian elephants are found in seasonally dry deciduous forests ( iv ), as well as in lush seasonal tropical forests. Photos: S. de Silva.

To assess the historical distribution of elephant habitats and changes in land use, it is possible to model elephant data and environmental factors to infer habitat suitability in an area and over time.

Researcher Shermin de Silva, founder of Trunks and Leaves Inc., which focuses on elephant conservation, and her colleagues estimated the change in the extent 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.

Suitable habitat for elephants

Habitats were classified as suitable if they exceeded a defined threshold modeled according to ecological criteria including, among other factors, percentage of primary forest and pasture, non-wooded vegetation, cropping and irrigation patterns, rates of timber felling, and The urbanization.

The authors compared an area within 100 kilometers of the current range of elephants in Asia and found that in 1700 100% of the area could have been considered suitable habitat, but in 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 their range of suitable elephant habitat, with the largest declines in China (about 94% of suitable habitat lost). and India (about 86% of suitable habitat lost).

Estimates over the Borneo territory suggest that it has gained suitable habitat for elephants. The authors suggest that the decline in suitable habitat for Asian elephants may lead to potential conflict between elephants and people.

The authors conclude that taking landscape history into account is important 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.

References

• ⁽¹⁾ Land-use change is associated with multi-century loss of elephant ecosystems in Asia. Scientific Reports.