A third of cacti are fac­ing ex­tinc­tion: study

The China Post - - INTERNATIONAL -

Thirty-one per­cent of cacti, some 500 species, face ex­tinc­tion due to hu­man en­croach­ment, ac­cord­ing to the first global as­sess­ment of the prickly plants, pub­lished Mon­day.

The find­ing places the cac­tus among the most threat­ened plant groups on Earth, ahead of mam­mals and birds and just be­hind corals, ac­cord­ing to the IUCN, an in­ter-gov­ern­men­tal con­ser­va­tion or­ga­ni­za­tion.

“The re­sults of this as­sess­ment come as a shock to us,” lead re­searcher Bar­bara Goettsch, co-chair of the IUCN’s Cac­tus and Suc­cu­lent Plant Spe­cial­ist Group, said in a state­ment.

“We did not ex­pect cacti to be so highly threat­ened.”

The IUCN (In­ter­na­tional Union for the Con­ser­va­tion of Na­ture) Red List is widely rec­og­nized as the gold stan­dard for mea­sur­ing ex­tinc­tion risk for an­i­mals and plants.

Cacti — na­tive to the Amer­i­cas, but in­tro­duced over cen­turies to Africa, Aus­tralia and Europe — are cru­cial links in the food chains of many an­i­mals, in­clud­ing hu­mans.

They are an es­sen­tial sources of sus­te­nance and wa­ter for deer, woodrats, rab­bits, coy­otes, lizards and tor­toises which, in re­turn, help spread cacti seeds.

Cac­tus flow­ers sup­ply nec­tar to hum­ming­birds and bats, along with bees, moths and other in­sects that help pol­li­nate the largely de­sert­d­welling plants.

In many parts of Cen­tral and South Amer­ica, cacti are used by peo­ple for food and medicine.

Mexico’s prickly pear cac­tus stem, for ex­am­ple, is highly nu­tri­tious, while the root of another species listed as near threat­ened — Ari­o­car­pus kotschoubeyanus — is com­monly used as an an­ti­in­flam­ma­tory.

‘Far-reach­ing con­se­quences’

Depend­ing on the species and the re­gion, dif­fer­ent forces have driven the de­cline in cacti, found the study, pub­lished in Na­ture Plants.

The top threat to cacti is ex­pand­ing agri­cul­ture, es­pe­cially in north­ern Mexico and the south­ern part of South Amer­ica.

Species na­tive to coastal ar­eas are be­ing dec­i­mated by residential and com­mer­cial de­vel­op­ment, while in south­ern Brazil con­ver­sion of land for eu­ca­lyp­tus plan­ta­tions is harm­ing at least 27 species, some of them al­ready on the en­dan­gered list.

“Their loss could have far-reach­ing con­se­quences for the bio­di­ver­sity and ecol­ogy of arid lands and for lo­cal com­mu­ni­ties de­pen­dent on wild-har­vested fruits and stems,” Goettsch said.

Re­searchers were also sur­prised to find that illegal trade in high­lyprized plants is also a key fac­tor in their dis­ap­pear­ance.

“The scale of the illegal wildlife trade — in­clud­ing trade in plants — is much greater than we pre­vi­ously thought,” said Inger An­der­sen, IUCN di­rec­tor gen­eral.

Some 86 per­cent of threat­ened cacti used in hor­ti­cul­ture are taken from wild pop­u­la­tions rather than cul­ti­vated, other stud­ies have shown. Europe and Asia are the big­gest mar­kets for this il­licit trade.

Min­ing is also a prob­lem, as il­lus­trated by the crit­i­cally en­dan­gered — the high­est level of threat be­fore ex­tinc­tion — Ar­ro­jadoa mary­la­niae, which only grows on a sin­gle type of white quartz rock.

Even the ex­pan­sion of fish farm­ing in huge man-made basins has en­croached on cacti habi­tat as land is cleared for aqua­cul­ture, es­pe­cially in north­west­ern Mexico.

Cacti range in size from one cen­time­ter in di­am­e­ter, to some 19 me­ters high.

The iconic Saguaro cac­tus — de rigeur in Hol­ly­wood West­erns — grows nearly as tall, and lives for up to 200 years.

Newspapers in English

Newspapers from Taiwan

© PressReader. All rights reserved.