Alien myths

The dogma that in­va­sive alien species should be erad­i­cated is now sus­pect


Are in­va­sive alien species re­ally a prob­lem?

AS NA­TIONS raise po­lit­i­cal bar­ri­ers (in some cases for­ti­fied by con­crete) on their bor­ders, th­ese are un­doubt­edly ter­ri­ble times for im­mi­grants. The same xeno­pho­bia colours our at­ti­tude to less ex­alted earth­lings—what are pe­jo­ra­tively called in­va­sive alien species. In a typ­i­cal illustration of this out­look, the Delhi govern­ment re­cently de­cided to purge the city’s forests of a grasp­ing bully called the vi­lay­ati kikar (foreign aca­cia) which, ecol­o­gists say, has cre­ated a mo­nop­oly over 80 per cent of the cap­i­tal’s ever-thin­ning woods by squeez­ing out na­tive flora and fauna, es­pe­cially its desi cousins. Sci­en­tists be­lieve, and des­per­ately hope, that weed­ing out the in­va­sive and re-in­tro­duc­ing the dis­ap­peared na­tives would some­how re­vive the old rhythms and pat­terns of the for­est. Vi­lay­ati kikar or vi­lay­ati ba­bool, as the name sug­gests, is an im­ported plant va­ri­ety hail­ing from Mex­ico, where it is known as mesquite. Tax­onomists know it as Prosopis juliflora, one of 44 known species of the genus Prosopis. Like thou­sands of other species, it too rode on the Em­pire’s band­wagon and set­tled in foreign lands across the world. The Bri­tish brought it to Delhi in the early 1900s and it spread like wild­fire as it could sur­vive in hos­tile con­di­tions such as drought. Iron­i­cally, the same virtues low­ered ground­wa­ter ta­bles and killed off na­tive species. Be that as it may, one can­not quite tell if one should treat the mesquite as hero or vil­lain. In the 1970s, in­ter­na­tional agen­cies like the UN hailed it as the “won­der tree” that could po­ten­tially ar­rest the march of the ad­vanc­ing desert in sub-Sa­ha­ran Africa. The sales pitch was ir­re­sistible: among other things, vil­lagers could use it as fire­wood; it could im­prove soil qual­ity by fix­ing

ni­tro­gen; and, birds would build bow­ers in it. No sur­pris­ingly, within two decades it had be­came a com­mon sight in many arid re­gions of the world, in­clud­ing In­dia.

It also be­came an im­por­tant source of liveli­hood as well as busi­ness for many com­mu­ni­ties. For in­stance, in In­dia, the vi­lay­ati

kikar ac­counts for 75 per cent of the fuelwood needs of vil­lagers lo­cated in dry re­gions like Ra­jasthan and Kutch. In Tamil Nadu and some parts of Kenya, some en­trepreneurs have cre­ated a lu­cra­tive busi­ness out of sell­ing kikar wood as char­coal to the lo­cal in­dus­try. And in South Africa, a pri­vate com­pany is mak­ing a huge profit out of sell­ing mesquite seeds as a medicine that can sta­bilise blood sugar lev­els.

How­ever, the hon­ey­moon was short-lived. In a 2013 book on African’s in­va­sive alien species, a unep con­sul­tant wrote that “most in­tro­duced

Prosopis species have turned out to be re­lent­lessly ag­gres­sive in­vaders” and that they were shap­ing “new green deserts” by de­plet­ing wa­ter ta­bles and push­ing out na­tive species. In fact, in 2005, a Kenyan com­mu­nity even sued the Food and Agri­cul­ture Or­ga­ni­za­tion and the Kenyan govern­ment for bring­ing mesquite to Kenya.

So just as it was lauded as a “won­der tree” to be­gin with, now it was de­monised as the “devil tree,” which ex­plains the cur­rent mad­ness to stamp it out across the world. This flip-flop raises some prickly ques­tions about how we un­der­stand alien in­va­sive species and whether we can re­store dam­aged ecosys­tems. That alien species are dan­ger­ous is a rel­a­tively re­cent no­tion. It was alien to most cul­tures un­til the turn of the 20th cen­tury when sci­en­tists started think­ing of ecosys­tems as in­tri­cately as­sem­bled ma­chines in which each na­tive species is a unique cog per­form­ing a pre­or­dained func­tion as prey, preda­tor, par­a­site, or scavenger. In other words, it is so tightly knit that there was lit­tle room for an in­ter­loper to do any­thing use­ful. So if a for­eigner does make un­fa­mil­iar ecosys­tem its home, it is likely to push out a na­tive species, often for­ever. Viewed from this per­spec­tive, all alien species, as sci­ence writer Fred Pearce put it in his provoca­tive The New

Wild, “are guilty un­til proved innocent.” This doc­trine drives most con­ser­va­tion projects to­day with am­bi­tious plans to re­store habi­tats by cleans­ing them of alien species—goats on Gala­pa­gos Is­lands, all preda­tors on New Zealand, and most in­va­sive trees in South Africa, to name a few.

But there is back­lash brew­ing against the dogma that treats aliens as evil and na­tives as good, which is nur­tured by sev­eral myths about na­ture. That na­ture is sta­ble and bal­anced un­til hu­mans dis­turb it is the first en­dur­ing myth of mod­ern con­ser­va­tion. In this scheme of things, aliens are au­to­mat­i­cally ren­dered per­sona non grata. Heretics, how­ever, be­lieve that there is no such thing as bal­ance of na­ture, and hence there is no need to fear aliens. In fact, they might play a cru­cial role in con­serv­ing na­ture.

The other en­dur­ing myth is that na­ture is pris­tine. But the truth is, as the Bri­tish land­scape his­to­rian, Oliver Rack­ham, writes, “most of the world’s land sur­face re­sults from long and com­plex in­ter­ac­tions be­tween hu­man ac­tiv­i­ties and nat­u­ral pro­cesses”. In the An­thro­pocene epoch, the tra­di­tional line di­vid­ing the nat­u­ral from the hu­man is blurred for­ever.

A good ex­am­ple of this blur­ring is the re­mark­able re­vival of aban­doned de­graded forests in Puerto Rico. The novel ecosys­tem, as such land­scapes are called now, was mostly em­bel­lished by colonists that, freak­ishly, also helped some of the na­tives to bounce back. Many rene­gade ecol­o­gists be­lieve that novel ecosys­tems fash­ioned from large swathes of de­graded habi­tats around the world is the fu­ture An­thro­pocene.

Given the new think­ing on alien species, the ecol­o­gist’s dream of restor­ing Delhi’s dam­aged ecosys­tem by knock­ing out the vi­lay­ati kikar ap­pears a lit­tle de­luded. How­ever, while it is al­right for us to fash­ion na­ture ac­cord­ing to our needs or aes­thet­ics or pol­i­tics, we must be clear that, as Pearce re­minds us in his book, “when we do this, it is for our­selves, and not for na­ture, whose needs are usu­ally rather dif­fer­ent”.



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