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