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Bio­di­ver­sity Cri­sis: The impacts of socio-​economic pres­sures on nat­ural flo­ras and faunas

pub­lished 17 April 2013 | mod­i­fied 05 April 2014

Ground squirrelA new study on extinc­tion risk based on exten­sive data from 7 tax­o­nomic groups and 22 Euro­pean coun­tries has shown that pro­por­tions of plant and ani­mal species being clas­si­fied as threat­ened on national Red Lists are more closely related to socio-​economic pres­sure lev­els from the begin­ning than from the end of the 20th cen­tury. This new find­ing by Ste­fan Dullinger of the Uni­ver­sity of Vienna and Franz Essl from the Aus­trian Envi­ron­ment Agency together with an inter­na­tional group of researchers is pub­lished on 15 April in the Pro­ceed­ings of the National Acad­emy of Sci­ences of the United States of Amer­ica.

It is well under­stood that the sur­vival of a sub­stan­tial and increas­ing num­ber of species is put at risk by human activ­ity via for instance habi­tat destruc­tion, envi­ron­men­tal pol­lu­tion or intro­duc­tion of alien species. Accord­ingly, the most recent global IUCN Red List (www​.iuc​nredlist​.org) clas­si­fies 31% of the 65,518 plant and ani­mal species assessed as endan­gered. How­ever, the tem­po­ral scale of cause-​effect rela­tion­ships is lit­tle explored. If extended time lags between human pres­sure and pop­u­la­tion decline are com­mon, then the full impact of cur­rent high lev­els of anthro­pogenic pres­sures on bio­di­ver­sity will only be realised decades into the future.

His­tor­i­cal legacy of species’ pop­u­la­tion losses
Tak­ing an his­tor­i­cal approach, the new study pro­vides cir­cum­stan­tial evi­dence that such time-​lags are indeed sub­stan­tial. The researchers demon­strate that pro­por­tions of vas­cu­lar plants, bryophytes, mam­mals, rep­tiles, drag­on­flies and grasshop­pers fac­ing medium to high extinc­tion risks are more closely matched to country-​specific indi­ca­tors of socio-​economic pres­sures (i.e. human pop­u­la­tion den­sity, per capita GDP, land use inten­sity) from the early or mid rather than the late 20th cen­tury. Accord­ingly, their results sug­gest a con­sid­er­able his­tor­i­cal legacy of species’ pop­u­la­tion losses. In a related analy­sis they also show that cur­rent spend­ing on envi­ron­men­tal con­ser­va­tion only has a weak mit­i­gat­ing effect. This find­ing implies that cur­rent con­ser­va­tion actions are effec­tive, but inad­e­quate in scale, to halt species losses.

The broad tax­o­nomic and geo­graphic cov­er­age indi­cates that a so-​called ‘extinc­tion debt’ is a wide­spread phenomenon.
Ste­fan Dullinger, Uni­ver­sity of Vienna »

“This iner­tia is wor­ry­ing as it implies that albeit num­bers of species clas­si­fied as threat­ened on Red Lists are increas­ing con­tin­u­ously and world­wide, these assess­ments might still under­es­ti­mate true extinc­tion risks”, explains Franz Essl from the Aus­trian Envi­ron­ment Agency.

Increase in global con­ser­va­tion effort is urgently needed
There­fore, the sci­en­tists write “mit­i­gat­ing extinc­tion risks might be an even greater chal­lenge if tem­po­ral delays mean many threat­ened species might already be des­tined towards extinc­tion”. They expect that min­imis­ing the mag­ni­tude of the cur­rent extinc­tion cri­sis might be an even greater chal­lenge when tem­po­ral delays are taken into account. There­fore a sub­stan­tial increase in global con­ser­va­tion effort is urgently needed to con­serve species diver­sity for future gen­er­a­tions, warns Dullinger.

(Source: Uni­ver­sität Wien press release, 16.04.2013)

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