Hu­mans have sliced up Earth’s wilder­ness into 600,000 pieces

Frag­men­ta­tion in the Ama­zon up­ends en­tire na­ture of its ecosys­tem

The Denver Post - - NATION & WORLD - By Chris Mooney

Sci­en­tists Thurs­day pro­vided a global quan­tifi­ca­tion of one of the most per­va­sive, but least rec­og­nized, ways that hu­mans are mar­ring the co­her­ence of the nat­u­ral world — by build­ing end­less num­bers of roads.

Roads frag­ment nat­u­ral habi­tats, and the more of them there are, the smaller and more com­pro­mised those habi­tats be­come. At the same time, roads give hu­mans ac­cess to re­mote, once pris­tine re­gions, where they can be­gin log­ging, min­ing, ac­ci­den­tally (or in­ten­tion­ally) start­ing fires and much else.

In the Ama­zon rain for­est, for in­stance, the frag­men­ta­tion of the land­scape that oc­curs be­cause of de­for­esta­tion — to which roads also con­trib­ute — up­ends the en­tire na­ture of the ecosys­tem. Once sun­light can pen­e­trate into the rain for­est from a cleared area to its side, rather than be­ing mostly blocked out by the lush canopy from above, the for­est floor dries out, the for­est it­self heats up, trees col­lapse more eas­ily, there isn’t enough range for many key species, and on and on.

The new study, pub­lished in the jour­nal Science by a team of 10 con­ser­va­tion sci­en­tists at in­sti­tu­tions in Ger­many, Greece, Poland, the United King­dom, Brazil and the United States, used an open-source, cit­i­zen science data­base of global roads. The re­searchers then com­bined this with an as­sess­ment from the re­search literature of the size of ar­eas along­side roads that are com­pro­mised eco­log­i­cally by them. This al­lowed them to count up the world’s re­main­ing truly un­tram­meled ar­eas and as­sess their num­ber and size.

They de­fined these ar­eas as start­ing 1 kilo­me­ter (a lit­tle over 3,000 feet) away from any road. “There are some ef­fects that go far be­yond 1 kilo­me­ter, ac­tu­ally. It’s a gra­di­ent of course, of im­pacts fad­ing out, but the ma­jor­ity of prob­lems is oc­cur­ring in this belt or buf­fer of 1 kilo­me­ter,” said Pierre Ibisch, the study’s first au­thor and a re­searcher at the Eber­swalde Uni­ver­sity for Sus­tain­able De­vel­op­ment in Ger­many.

Us­ing this met­ric, the study found that the Earth’s land ar­eas (ex­clud­ing Antarc­tica and Green­land) were 80 per­cent road­less, which may sound like a good thing — but peer­ing in closer, the re­searchers found that roads had divided that land area into some 600,000 pieces. More than half of these were less than a half a mile in area.

Only 7 per­cent of the frag­ments were very large — more than about 39 square miles. Some of the largest un­tram­meled ar­eas were in the Ama­zon rain for­est, north­ern or bo­real forests and Africa.

Data in­di­cate that eco­nomic de­vel­op­ment and the con­cen­tra­tion of roads go hand in hand — thus, ad­vanced economies in the United States, Europe and Ja­pan seem to have lit­tle road­less area at all.

And it’s im­por­tant to ac­knowl­edge, as the study notes, that the re­search is prob­a­bly go­ing on an in­com­plete data set of the to­tal num­ber of roads in the world. In other words, the pic­ture is likely worse.

The re­searchers then went on to iden­tify the ar­eas that were road­less but also had the great­est “eco­log­i­cal value” — for in­stance, un­tram­meled rain for­est sup­ports much more species bio­di­ver­sity than road­less desert. These are the ar­eas that, now, are most worth pro­tect­ing from fur­ther in­cur­sions.

“The big­gest block, most bio­di­verse road­less ar­eas would be found in the Ama­zon,” Ibisch said. “We also have valu­able road­less ar­eas in the Congo Basin. But to a lesser ex­tent, we have more ex­ten­sive frag­men­ta­tion there al­ready. And we also would find in­ter­est­ing road­less ar­eas in South­east Asia, in the trop­ics. But there are also valu­able road­less ar­eas in the bo­real zone and even stretch­ing out into the tun­dra in north­ern Rus­sia.”


Michael Reaves, The Denver Post

Cy­clists climb Trail Ridge Road dur­ing Ride the Rock­ies on June 16.

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