Why eco-sourc­ing makes sense

The Tribune (NZ) - - GARDENING - DR. GIL­LIAN RAP­SON, ECOL­OGY GROUP, MASSEY UNIVER­SITY.

The en­thu­si­asm Ki­wis have for restor­ing na­tive veg­e­ta­tion is grow­ing, as we face a prob­lem­atic en­vi­ron­men­tal fu­ture.

Na­tive plant­ing projects are con­stantly be­ing ini­ti­ated and de­vel­oped, es­pe­cially around rivers and streams. How­ever, it is im­por­tant to con­sider the source of the plants be­ing used.

For most species, ecol­o­gists have no idea of the ap­pro­pri­ate size of the area to source from - is it an is­land, an eco­log­i­cal dis­trict, or much smaller - as in the size of a sports field? Why is this im­por­tant? Plants (and an­i­mals too) vary ge­net­i­cally from place to place, and a geno­type that func­tions well in one place, may not func­tion well in an­other. It may be un­able to re­pro­duce, or to in­ter­act nor­mally with the other mem­bers of the veg­e­ta­tion.

Few Manawatu plant nurs­eries grow eco-sourced ma­te­rial suit­able for the dif­fer­ent parts of our re­gion. In­stead, projects need to set up a seed col­lec­tion and grow­ing sys­tem for them­selves so they can use the near­est ap­pro­pri­ate plants to pro­vide seed or seedlings for each lo­ca­tion.

For ex­am­ple, along the Kahuter­awa Stream, restora­tion plant­ing run by Lin­ton Army Camp, Hori­zons and Massey Univer­sity, only uses ma­te­rial sourced from within the plant­ing zone it­self where pos­si­ble. Be­cause it is a long thread of stream with sev­eral rem­nant stands of na­tive veg­e­ta­tion, we are able, for some species, to source at an even finer scale.

In the fu­ture, ecol­o­gists will be able to study how much this matters. In­for­ma­tion about eco-sourc­ing can be found at the NZ Plant Con­ser­va­tion Net­work web­site, www.nzpcn.org.nz.

Us­ing non-eco-sourced plants could be an eco­log­i­cal dis­as­ter in wait­ing. Some ar­gue that plant­ing non-eco-sourced ma­te­rial will im­prove the veg­e­ta­tion’s re­spon­sive­ness to cli­mate change.

How­ever, the ef­fects of cli­mate change are hard to pre­dict, so we don’t know whether to use species from warmer ar­eas, from wet­ter or sea­son­ally dry ar­eas, from sim­i­lar veg­e­ta­tion types to ours, or from dif­fer­ent ones.

Species will not all re­spond in the same way to cli­mate change any­how. It seems best to leave na­ture to make the de­ci­sions about manag­ing that as­pect of our ecosys­tems. At least for now, lo­cal is best.

PHOTO: GIL­LIAN RAP­SON/ SUP­PLIED

Plants for the Kahuter­awa Stream.

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