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201903Mar12:57

Asian ele­phants may lose up to 42 per­cent of suit­able habi­tats in India and Nepal until 2070

Infor­ma­tion
pub­lished 03 March 2019 | mod­i­fied 16 March 2019

Pro­tect­ing and expand­ing suit­able habi­tats for wildlife is key to the con­ser­va­tion of endan­gered species, but owing to cli­mate and land use change the ideal habi­tats of today may not be fit­ting in 30 or 50 years. An inter­na­tional team of sci­en­tists there­fore pre­dicted range shifts of Asian ele­phants in India and Nepal using species dis­tri­b­u­tion mod­els based on dis­tri­b­u­tion data for the ele­phants and cli­mate pro­jec­tions. While a few regions in the north and north­east of the sub­con­ti­nent may pro­vide more suit­able habi­tats in the future, over­all a heavy loss is prob­a­ble in all sce­nar­ios. The com­plex effects of envi­ron­men­tal change on the dis­tri­b­u­tion of the ele­phants is elu­ci­dated in a paper pub­lished on 6 Feb­ru­ary in the Jour­nal Diver­sity and Dis­tri­b­u­tions.

Asian elephants in the wildAsian ele­phants.
Image: Priya Davi­dar & Jean-​Philippe Puyravaud

It is well known that cli­mate change, land use change, changes in water cycles, and other influ­enc­ing fac­tors will cause redis­tri­b­u­tion of species – directly or indi­rectly. The details of these processes are very com­plex, how­ever, as effects of global change is man­i­fested very dif­fer­ently on a local scale. In a mas­sive effort, sci­en­tists from Spain, India, Nepal, Myan­mar, Italy, and Ger­many worked together in order to assess the com­bined effects of human pres­sures and cli­mate change on Asian ele­phants’ dis­tri­b­u­tion, embed­ded in the human-​dominated land­scapes in India and Nepal. “We com­piled a large data­base of more than four thou­sand ele­phant occur­rences and a large geo­data­base of envi­ron­men­tal pre­dic­tor vari­ables cov­er­ing India and Nepal for this study,” explains Suren­dra P. Goyal (Wildlife Insti­tute of India). In a first step, this allowed the sci­en­tists to pre­dict the cur­rent spa­tial dis­tri­b­u­tion of Asian ele­phants as a func­tion of envi­ron­men­tal vari­ables. “In addi­tion to ongo­ing human-​induced dis­tur­bance, espe­cially in the form of land-​use change, ele­phant dis­tri­b­u­tion is influ­enced by com­plex local scale inter­ac­tions among pre­cip­i­ta­tion and tem­per­a­ture, com­pli­cated by sea­sonal mon­soon in this region,” explains lead author Rajapan­dian Kana­garaj from the National Museum of Nat­ural Sci­ences (MNCN) in Madrid (Spain). The sci­en­tists esti­mated that around 256,000 km2 of habi­tat are suit­able for ele­phants in India and Nepal.
In a sec­ond step the effects of cli­mate changes were included into the dis­tri­b­u­tion model to pre­dict future ele­phant dis­tri­b­u­tions and pos­si­ble range shifts. Rely­ing on cli­mate and land use data pro­jec­tions for 2050 and 2070, dif­fer­ent sce­nar­ios were calculated.

We antic­i­pate that ele­phant range would likely shift towards higher ele­va­tions in the Himalayas, and along a gra­di­ent of water avail­abil­ity, instead of a sim­ple uni­di­rec­tional range shift towards higher ele­va­tions and lat­i­tudes typ­i­cally expected when tem­per­a­ture is the prin­ci­pal factor.

Miguel B. Araújo, co-​author, Depart­ment of Bio­geog­ra­phy and Global Change, National Museum of Nat­ural Sci­ences, CSIC, Madrid, Spain

All sce­nar­ios strongly indi­cate that the inter­ac­tion between cli­mate change and land use will com­pound exist­ing threats to the ele­phant. In a sce­nario where only cli­mate change is included, the loss of poten­tial habi­tat is more mod­er­ate, but still sub­stan­tial with a 17.1 per­cent loss in one sce­nario in 2070. “The neg­a­tive effect is espe­cially severe in the human-​dominated land­scapes in east­ern and south­ern India,” say Priya Davi­dar and Jean-​Philippe Puyravaud (Sigur Nature Trust, India). Gain in poten­tial habi­tat is indi­cated in north­ern and north­east­ern habi­tats par­tic­u­larly along the val­leys in the Himalayan foothills. “Our model pro­jec­tions sug­gest that the pro­jected future changes in the dis­tri­b­u­tion of ele­phants in India and Nepal would be dri­ven mainly by changes in the cli­matic water bal­ance, fol­lowed by changes in tem­per­a­ture and other ongo­ing human-​induced dis­tur­bance” Kana­garaj and Araújo con­clude.
For that rea­son, build­ing com­pre­hen­sive and robust spa­tial mod­els is cru­cial to assess the impact of envi­ron­men­tal changes in wildlife pop­u­la­tions. “The data­base con­sisted of 115 envi­ron­men­tal vari­ables: 60 cli­matic, 16 human dis­tur­bance, 29 for­est and veg­e­ta­tion and 10 topo­graphic vari­ables, all at a grid res­o­lu­tion of 1 kilo­me­tre,” says Thorsten Wie­gand, mod­el­ling expert from the Envi­ron­men­tal Research Cen­tre (UFZ), Leipzig. Occur­rence data relied on 4,626 ele­phant sight­ings between 1990 and 2017, with the vast major­ity of sight­ings after 2002. “The art of mod­el­ling here was dis­till­ing the most bio­log­i­cally plau­si­ble envi­ron­men­tal pre­dic­tors and elim­i­nat­ing redun­dant cor­re­la­tions,” Stephanie Kramer-​Schadt, head of the depart­ment of Eco­log­i­cal Dynam­ics at the Leib­niz Insti­tute for Zoo and Wildlife Research (Leibniz-​IZW), explains the meth­ods. The team cal­cu­lated and tested sev­eral mod­els which can fore­cast the dis­tri­b­u­tion only from the remain­ing nine envi­ron­men­tal vari­ables. “In the end we have to acknowl­edge that [we, ed.] are deal­ing with mod­els of dis­tri­b­u­tion and envi­ron­men­tal change,” Kramer-​Schadt adds. This approach enabled the team to develop highly prob­a­ble sce­nar­ios for range shifts of the ele­phants under global change, but the pre­dic­tions are always con­nected with a level of uncertainty.

Asian elephant future habitat suitability in India and NepalMap of pre­dicted habi­tat suit­abil­ity (on top of hill­shade map) for Asian ele­phant in India and Nepal using the con­sen­sus model derived from the ensem­ble approach. Map pro­jec­tion: Uni­ver­sal Trans­verse Mer­ca­tor zone 44 N.
Rajapan­dian Kana­garaj et al., 2019. Pre­dict­ing range shifts of Asian ele­phants under global change. in Diver­sity and Dis­tri­b­u­tions.
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The results of this com­pre­hen­sive study nev­er­the­less have impor­tant impli­ca­tions con­cern­ing con­ser­va­tion efforts as the suit­abil­ity maps and future pro­jec­tions can be effec­tively used to iden­tify crit­i­cal habi­tat areas that require imme­di­ate con­ser­va­tion attempts. Fur­ther­more the pro­jec­tions can inspire adjust­ments to cur­rent habi­tat pro­tec­tion strate­gies. A sup­ple­men­tary analy­sis high­lighted the impor­tance of con­nected habi­tats: “The model only pre­dicts the suit­abil­ity of a 1 km2 grid cell with­out account­ing for the move­ment capac­ity of ele­phants and their home range sizes, so we added the core range analy­sis to iden­tify high suit­abil­ity areas larger than the size of two aver­age home ranges and an analy­sis of the con­nec­tiv­ity of core areas that con­sid­ers the max­i­mal dis­place­ment capac­ity of ele­phants,” says Kana­garaj. “The results under­line the pres­sure that is expected on the habi­tats on south­ern and east­ern India as it is where large core areas can be found,” says Suren­dra P. Goyal. Fur­ther, the analy­sis sug­gests that the frag­mented core areas that are located along the foothills forests and flood­plains of the Himalaya could be con­nected by a mix­ture of poor‐ and high‐quality habi­tat that should form spe­cific tar­gets for man­age­ment. These results pro­vide a first assess­ment of areas that could pro­vide con­nec­tiv­ity among core areas.

We are cer­tain that con­ser­va­tion of remain­ing habi­tat will always remain the cen­tre­piece of bio­di­ver­sity con­ser­va­tion,” the team states. “Our study pro­vides a first assess­ment on the effect of cli­mate change on the dis­tri­b­u­tion of the Asian ele­phant in its major habi­tats in India and Nepal, which could help other assess­ments over its entire range across South and South‐East Asia, and be use­ful for devel­op­ing man­age­ment plans for wildlife con­ser­va­tion under the aegis of cli­mate change.”

(Source: Leib­niz Forschungsver­bund Berlin e.V. press release, 28.02.2019)


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Tiger range countries map

Tiger map” (CC BY 2.5) by Sander­son et al., 2006.

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