Pine guz­zlers great risk to Cape’s water

Weekend Argus (Saturday Edition) - - FRONT PAGE - SHEREE BEGA

CAPE Town and Port El­iz­a­beth could lose as much as 36 per­cent of their water sup­ply in the next few decades, if the gov­ern­ment’s cel­e­brated Work­ing for Water pro­gramme does not im­prove its man­age­ment of in­va­sive pine trees in pro­tected ar­eas of the Cape Flo­ral Re­gion.

In a new as­sess­ment, re­searchers from sev­eral of the coun­try’s ma­jor con­ser­va­tion out­fits warn un­less “bold steps” are taken to im­prove the man­age­ment of in­va­sive pine trees in pro­tected ar­eas of the Cape Flo­ral Re­gion, a bio­di­ver­sity hot spot of global sig­nif­i­cance, “Cape Town and other coastal towns and cities along the Gar­den Route stand to lose more than a third of their cur­rent water sup­ply over the next 30 to 50 years”.

In the ar­ti­cle, “His­tor­i­cal Costs and Pro­jected Fu­ture Sce­nar­ios for the Man­age­ment of In­va­sive Alien Plants in Pro­tected Ar­eas in the Cape Floris­tic Re­gion”, re­searchers from the DST-NRF Cen­tre for In­va­sion Bi­ol­ogy at Stel­len­bosch Univer­sity, SANParks, CapeNa­ture and Nel­son Man­dela Met­ro­pol­i­tan Univer­sity re­veal the find­ings of their as­sess­ment of the his­tor­i­cal costs, and ex­tent of ef­forts to con­trol in­va­sive plants in the CFR since 1995.

The study’s lead au­thor, ecol­o­gist Pro­fes­sor Brian van Wil­gen of the Cen­tre for In­va­sion Bi­ol­ogy, said if bold steps were not taken to im­prove man­age­ment, “a great deal of money would have been, and will con­tinue to be wasted”.

The prob­lem “is sim­ply go­ing to run away from us, grow­ing faster than we can con­tain it”, he warned. “Cape Town and all other coastal towns and cities up to Port El­iz­a­beth stand to lose up to 36 per­cent of their water sup­ply, putting a se­ri­ous damper on eco­nomic growth and fu­ture em­ploy­ment op­por­tu­ni­ties for tens of thou­sands of peo­ple.”

The study, pub­lished in the jour­nal Bi­o­log­i­cal Con­ser­va­tion last month, es­ti­mated R564 mil­lion had been spent to date on at­tempts to con­trol alien plants in 25 of the CFR’s pro­tected ar­eas. But while the fo­cus had been on the erad­ica- tion of aca­cias, in­vad­ing pine trees posed a much greater threat in the long term, as they cre­ated shade which halts the growth of na­tive ground­cover plants.

The ar­ti­cle notes how, over the past three years, the Work­ing for Water pro­gramme, “praised world­wide as a unique con­ser­va­tion ini­tia­tive” to clear in­va­sive plants while pro­vid­ing so­cial ser­vices and ru­ral em­ploy­ment, has of­fered jobs to an av­er­age of more than 20 000 peo­ple a year.

Yet, after 20 years, it had reached only a small pro­por­tion – up to 13 per­cent – of the to­tal in­vaded area in the Cape Flo­ral Re­gion, where more than 1 000 in­dige­nous plant species had been iden­ti­fied as be­ing threat­ened by in­va­sive alien species.

“If in­va­sions were to reach the full ex­tent of their po­ten­tial dis­tri­bu­tion, over­all bio­di­ver­sity in the re­gion could be slashed by as much as 40 per­cent,” the ar­ti­cle noted.

The Bi­o­log­i­cal Con­ser­va­tion study says R170 m will be needed to bring re­main­ing in­va­sions in the CFR un­der con­trol, where only pines and hakeas are con­trolled, and a stag­ger­ing 2 608km² where all species are con­trolled.

Van Wil­gen said the es­sen­tial el­e­ment of an im­proved man­age­ment ap­proach would be to prac­tise “con­ser­va­tion triage”, fo­cus­ing ef­fort only on pri­or­ity ar­eas and species, and ac­cept­ing trade­offs be­tween con­serv­ing bio­di­ver­sity and re­duc­ing in­va­sions.

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