Rewilding, a new approach to protecting biodiversity

Biod­iversity is enter­ing its 6^th mass extinc­tion, the first to be caused entirely by a single spe­cies: man­kind. A mass extinc­tion is defined as the loss of more than three quar­ters of spe­cies in a short geo­lo­gic­al time span. Cur­rent extinc­tion rates are the fast­est ever observed¹. And it is now clear that this extinc­tion con­cerns a large pro­por­tion of liv­ing organ­isms: birds, mam­mals as well as inver­teb­rates, which are dis­ap­pear­ing at even faster rates².

While pro­tect­ing biod­iversity is neces­sary, it has not been enough, and restor­ing degraded eco­sys­tems is now essen­tial³. This is not a new obser­va­tion: the United Nations has adop­ted a res­ol­u­tion declar­ing the dec­ade 2021–2030 to be the dec­ade of eco­sys­tem res­tor­a­tion⁴. After sev­er­al years of sci­entif­ic debate, the concept of “rewild­ing” is becom­ing a new flag­ship tool for pro­tect­ing nature.

“Rewild­ing became fash­ion­able at the end of the 1990s and has exploded since the 2010s at a time when the pro­tec­tion of biod­iversity is becom­ing increas­ingly tech­no­crat­ic” explains Simon Chol­let. In 1998, two Amer­ic­an eco­lo­gists pub­lished their first art­icle⁵ men­tion­ing the concept of rewild­ing. The approach was based on three key ele­ments: large reserves that were strictly pro­tec­ted, inter­con­nec­ted and in which key spe­cies were rein­tro­duced. “At that time, we under­stood that many eco­sys­tems were con­trolled by a few “key” spe­cies,” explains Simon Chol­let. The lead­ing example was the rein­tro­duc­tion of the wolf into Yel­low­stone Nation­al Park (United States) in 1995, 70 years after its dis­ap­pear­ance. The inter­ac­tion of this pred­at­or with cer­tain prey triggered a cas­cade of reac­tions⁶, affect­ing the entire eco­sys­tem and even trans­form­ing landscapes.

Since then, the defin­i­tion of rewild­ing has evolved, cul­min­at­ing in a con­sensus in 2021⁷. “Rewild­ing centres on the notion of the autonomy of nat­ur­al pro­cesses, in con­trast to the cur­rent effects of human activ­ity, which anni­hil­ate the autonomy of nature,” states Simon Chol­let. Offer­ing nature the chance to restore itself is a real innov­a­tion in the field of biod­iversity pro­tec­tion⁸. Clé­mentine Mutil­lod explains:  “The aim of rewild­ing is to restore a degraded eco­sys­tem to its ori­gin­al func­tions. Unlike oth­er pro­tec­tion approaches such as eco­lo­gic­al res­tor­a­tion, rewild­ing does not focus on spe­cies, par­tic­u­larly rare and pro­tec­ted spe­cies: the spe­cif­ic com­pos­i­tion of the eco­sys­tem can change as long as its func­tions are restored. This allows us to take the dynam­ics of liv­ing things into account.”

Faced with the impact of human activ­ity – includ­ing cli­mate change – the concept is very appeal­ing. “The ini­tial idea was not linked to cli­mate change,” points out Clé­mentine Mutil­lod. “But today, many sci­ent­ists believe that rewild­ing could help biod­iversity to cush­ion the effects of cli­mate change.” Anoth­er advant­age is that it gives biod­iversity back its right­ful place, pla­cing it on an equal foot­ing with human­ity. “His­tor­ic­ally, this concept appealed to those involved in pro­tect­ing biod­iversity, who were fed up with the notion of “ser­vice”,” points out Simon Chol­let. Eco­sys­tem ser­vices – the ser­vices that eco­sys­tems provided to human­ity, guar­an­tee­ing its well-being and devel­op­ment – have been used in recent years to jus­ti­fy the import­ance of pro­tect­ing nature. 

Today, how­ever, many of the argu­ments put for­ward by sci­ent­ists depart from this anthro­po­centric vis­ion, in which nature is there solely to serve us. Simon Chol­let has no short­age of argu­ments: “For the first time in four bil­lion years, a single com­pon­ent of biod­iversity (humans) is lead­ing to the decline of all liv­ing things. Halt­ing this phe­nomen­on is a mor­al and eth­ic­al respons­ib­il­ity, which is the main reas­on why we need to pro­tect nature.” He con­tin­ues: “Of course, nature is use­ful to us: without it, we couldn’t live, because it provides us with so much, par­tic­u­larly our food via pol­lin­at­ors. But its use­ful­ness does not jus­ti­fy redu­cing it to a ser­vice, and nature should not be con­sidered simply as a pro­vider for our activities.”

So how can nature be restored through rewild­ing? There is no one single answer, and many dif­fer­ent approaches exist. They fall into two broad cat­egor­ies: pass­ive approaches involve remov­ing as much human pres­sure as pos­sible. These have been developed by forest man­agers, in par­tic­u­lar, through the use of strict bio­lo­gic­al reserves since the 1960s – even before the concept of rewild­ing had been defined! In act­ive approaches, humans always inter­vene, for example by rein­tro­du­cing cer­tain pred­at­ory spe­cies. Some even take the concept to extremes: as rewild­ing aims to restore the ini­tial func­tions of a degraded eco­sys­tem, sci­ent­ists (not­ably Amer­ic­an and Rus­si­an) are ima­gin­ing restor­ing func­tion­al eco­sys­tems from the Pleis­to­cene, the geo­lo­gic­al era pre­ced­ing our own (-2.58 mil­lion to ‑11,700 years ago). These eco­sys­tems were com­pletely dis­rup­ted by the dis­ap­pear­ance of cer­tain mega-herb­i­vores (mam­moths, for example), which were hunted by humans.

“Rewild­ing is only rarely applied at the moment, but it is one of the con­ser­va­tion approaches that sci­ent­ists and con­ser­va­tion man­agers are most inter­ested in,” says Simon Chol­let. It is some­times dif­fi­cult to recon­cile the con­sequences of rewild­ing with loc­al pop­u­la­tions. The approach often requires large areas free of any human activ­ity, which can trig­ger dis­putes over land own­er­ship. And the rein­tro­duc­tion of large pred­at­ors in act­ive approaches can lead to col­li­sions with cars or dam­age to nearby live­stock. “So far, there has been little eval­u­ation of the effect­ive­ness of rewild­ing, unlike oth­er approaches such as eco­lo­gic­al res­tor­a­tion,” explains Clé­mentine Mutil­lod. “The res­ults depend a great deal on the con­text, but on the whole the exper­i­ences have been fairly pos­it­ive in terms of restor­ing the degraded eco­sys­tem. Simon Chol­let adds: “It’s not a mir­acle solu­tion, but cer­tain res­ults are well estab­lished, such as the bene­fi­cial role of pred­at­ors and large herb­i­vores on biod­iversity.” While rewild­ing is not the new stand­ard for pro­tect­ing biod­iversity, it is becom­ing a com­ple­ment­ary approach to the his­tor­ic­al meth­ods used in land management.

Anaïs Marechal