Between April 15-18, Sustainable Farming Fund wilding project personnel, Nick Ledgard and Thomas Paul of Scion, visited Tarndale on Molesworth Station and Hitaua Bay in the Marlborough Sounds to assess what happens with vegetation successions after wildings have been removed. 
At Tarndale, over 200 ha of conifers have been removed since 1990, much of them in short time over the last 2 years.  Nick and Thomas first looked at tree ‘carcasses’ felled in the early 1990s. It appears that, after an initial flush of vigorous growth (mostly native and introduced grasses) after felling, probably as a result of improved shelter and nutrients, the sites were returning to sorrel and hawkweed dominance.  There was little sign of the native herbs, forbs and mat plants present before conifer planting and still growing in unplanted areas alongside.

The other wilding removal sites inspected were where small wildings (up to 3-4 m tall) were mulched by a tractor-driven drum mulcher, and where larger trees had been windrowed by machines (a combination of digger and bulldozer).  One season later there was still much bare ground and the dominant plants were sorrel, hawkweed and browntop.  No young wildings were found, but in the absence of seed sowing, fertilising and grazing (present in half the area), they are likely to reappear within the next year or two.  The ‘before and after’ photos show where young wildings have been mulched, after which grass seed and fertiliser was applied.

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 Dense Scots pine wildings (aged 5-7years) at Tarndal, Molesworth station

 

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 Same site after wildings removal by mulching (foreground) and older trees by felling  and/or windrowing with a digger/dozer combination


  
 


In the Sounds, there is a huge difference in vegetation successions occurring where mature radiata pine has been felled and harvested, and where they have been poisoned.  At both sites assessed, before the trees were removed there was a closed canopy of pines with living no understory.  The photos show that 10 years after poisoning, the regrowth of native species has been impressive, with no conifer wildings amongst them.

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 Assessing vegetation in Marlborough Sounds under mature pine stand, poisoned 10 years previously - note  native regrowth and no wildings

Compare that to the other site, where within 5 years of felling and harvesting, many thousands of young pines are rapidly becoming the dominant canopy cover.  Such differences are not hard to see, but before Nick and Thomas’s visit no-one had quantified these changes.

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 Assessing vegetation in Marlborough Sounds on site where mature pines have been felled and harvested 5 years previously - note few natives and dense widling regeneration.